Merge branch 'master' into colorspace-transforms

.travis.yml

@@ -6,7 +6,7 @@ matrix:
     - os: linux # Ubuntu 14.04
       dist: trusty
       sudo: required
-      dotnet: 2.1.4
+      dotnet: 2.1.300-rc1-008673
       mono: latest
 #    - os: osx # OSX 10.11
 #      osx_image: xcode7.3.1
@@ -21,7 +21,7 @@ branches:
 script:
   - git submodule -q update --init
   - dotnet restore
-  - dotnet test tests/ImageSharp.Tests/ImageSharp.Tests.csproj -c Release -f "netcoreapp2.0"
+  - dotnet test tests/ImageSharp.Tests/ImageSharp.Tests.csproj -c Release -f "netcoreapp2.1"
 
 env:
   global:

README.md

@@ -115,17 +115,21 @@ For more examples check out:
 
 ### Manual build
 
-If you prefer, you can compile ImageSharp yourself (please do and help!), you'll need:
+If you prefer, you can compile ImageSharp yourself (please do and help!)
 
-- [Visual Studio 2017 (or above)](https://www.visualstudio.com/en-us/news/releasenotes/vs2017-relnotes)
-- The [.NET Core SDK Installer](https://www.microsoft.com/net/core#windows) - Non VSCode link.
+- Using [Visual Studio 2017 Preview](https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-preview-relnotes)
+  - Make sure you have the latest version installed
+  - Make sure you have [the newest 2.1 RC1 SDK installed](https://www.microsoft.com/net/core#windows)
 
-Alternatively on Linux you can use:
+- Using [Visual Studio 2017](https://www.visualstudio.com/en-us/news/releasenotes/vs2017-relnotes)
+  - If you are unable and/or don't want to build ImageSharp.Tests against 2.1 RC, remove the `netcoreapp2.1` target [from TargetFrameworks](https://github.com/SixLabors/ImageSharp/blob/master/tests/ImageSharp.Tests/ImageSharp.Tests.csproj#L3) locally
+
+Alternatively, you can work from command line and/or with a lightweight editor on **both Linux/Unix and Windows**:
 
 - [Visual Studio Code](https://code.visualstudio.com/) with [C# Extension](https://marketplace.visualstudio.com/items?itemName=ms-vscode.csharp)
 - [.Net Core](https://www.microsoft.com/net/core#linuxubuntu)
 
-To clone it locally click the "Clone in Windows" button above or run the following git commands.
+To clone ImageSharp locally click the "Clone in Windows" button above or run the following git commands.
 
 ```bash
 git clone https://github.com/SixLabors/ImageSharp

appveyor.yml

@@ -1,21 +1,34 @@
 version: 1.0.0.{build}
-image: Visual Studio 2017
+image: Visual Studio 2017 Preview
 
 # prevent the double build when a branch has an active PR
 skip_branch_with_pr: true
 
 environment:
   matrix:
+    ### TODO: Enable the netcoreapp2.1 target when RC2 has been released!
+
+    #- target_framework: netcoreapp2.1
+    #  is_32bit: False
+
+    #- target_framework: netcoreapp2.1
+    #  is_32bit: True
+
+    - target_framework: netcoreapp2.0
+      is_32bit: False
+
+    - target_framework: net471
+      is_32bit: False
+
     - target_framework: net471
       is_32bit: True
+
     - target_framework: net462
       is_32bit: False
+
     - target_framework: net462
       is_32bit: True
-    - target_framework: net471
-      is_32bit: False
-    - target_framework: netcoreapp2.0
-      is_32bit: False
+    
     #- target_framework: netcoreapp2.0 # As far as I understand, 32 bit test execution is not supported by "dotnet xunit"
     #  is_32bit: True
     #- target_framework: mono
@@ -39,7 +52,7 @@ install:
 
 before_build:
   - git submodule -q update --init
-  - cmd: dotnet --version
+  - cmd: dotnet --info
   
 build_script:
 - cmd: build.cmd
@@ -60,4 +73,4 @@ deploy:
       secure: V/lEHP0UeMWIpWd0fiNlY2IgbCnJKQlGdRksECdJbOBdaE20Fl0RNL7WyqHe02o4
     artifact: /.*\.nupkg/
     on:
-      branch: master
+      branch: master

run-tests.ps1

@@ -15,6 +15,32 @@ function VerifyPath($path, $errorMessage) {
     }
 }
 
+function CheckSubmoduleStatus() {
+    $submoduleStatus = (git submodule status) | Out-String
+    # if the result string is empty, the command failed to run (we didn't capture the error stream)
+    if ($submoduleStatus) {
+        # git has been called successfully, what about the status?
+        if (($submoduleStatus -match "\-") -or ($submoduleStatus -match "\(\(null\)\)"))
+        {
+            # submodule has not been initialized!
+            return 2;
+        } 
+        elseif ($submoduleStatus -match "\+")
+        {
+            # submodule is not synced:
+            return 1;
+        }
+        else {
+            # everything fine:
+            return 0;
+        }
+    } else {
+          # git call failed, so we should warn
+          return 3;
+    }
+}
+
+
 if ( ($targetFramework -eq "netcoreapp2.0") -and ($env:CI -eq "True") -and ($is32Bit -ne "True")) {
     # We execute CodeCoverage.cmd only for one specific job on CI (netcoreapp2.0 + 64bit )
     $testRunnerCmd = ".\tests\CodeCoverage\CodeCoverage.cmd"
@@ -64,4 +90,23 @@ Invoke-Expression $testRunnerCmd
 
 cd $PSScriptRoot
 
-exit $LASTEXITCODE
+$exitCodeOfTests = $LASTEXITCODE;
+
+if (0 -ne ([int]$exitCodeOfTests)) {
+    # check submodule status
+    $submoduleStatus = CheckSubmoduleStatus
+    if ([int]$submoduleStatus -eq 1) {
+        # not synced
+        Write-Host -ForegroundColor Yellow "Check if submodules are up to date. You can use 'git submodule update' to fix this";
+    } elseif ($submoduleStatus -eq 2) {
+        # not initialized
+        Write-Host -ForegroundColor Yellow "Check if submodules are initialized. You can run 'git submodule init' to initialize them."
+    } elseif ($submoduleStatus -eq 3) {
+        # git not found, maybe submodules not synced?
+        Write-Host -ForegroundColor Yellow "Could not check if submodules are initialized correctly. Maybe git is not installed?"
+    } else {
+        #Write-Host "Submodules are up to date";
+    }
+}
+
+exit $exitCodeOfTests

src/ImageSharp.Drawing/ImageSharp.Drawing.csproj

@@ -38,7 +38,7 @@
     </ItemGroup>
     <ItemGroup>
         <PackageReference Include="SixLabors.Core" Version="1.0.0-beta0005" />
-        <PackageReference Include="SixLabors.Shapes" Version="1.0.0-beta0004" />
+        <PackageReference Include="SixLabors.Shapes" Version="1.0.0-ci0018" />
         <PackageReference Include="SixLabors.Shapes.Text" Version="1.0.0-beta0004" />
         <AdditionalFiles Include="..\..\stylecop.json" />
         <PackageReference Include="StyleCop.Analyzers" Version="1.1.0-beta004">

src/ImageSharp.Drawing/Processing/Drawing/Brushes/BrushApplicator.cs

@@ -79,6 +79,10 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Brushes
                     {
                         amountSpan[i] = scanline[i] * this.Options.BlendPercentage;
                     }
+                    else
+                    {
+                        amountSpan[i] = scanline[i];
+                    }
 
                     overlaySpan[i] = this[x + i, y];
                 }

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/ColorStop{TPixel}.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics;
+
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// A struct that defines a single color stop.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    [DebuggerDisplay("ColorStop({Ratio} -> {Color}")]
+    public struct ColorStop<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ColorStop{TPixel}" /> struct.
+        /// </summary>
+        /// <param name="ratio">Where should it be? 0 is at the start, 1 at the end of the Gradient.</param>
+        /// <param name="color">What color should be used at that point?</param>
+        public ColorStop(float ratio, TPixel color)
+        {
+            this.Ratio = ratio;
+            this.Color = color;
+        }
+
+        /// <summary>
+        /// Gets the point along the defined gradient axis.
+        /// </summary>
+        public float Ratio { get; }
+
+        /// <summary>
+        /// Gets the color to be used.
+        /// </summary>
+        public TPixel Color { get; }
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/EllipticGradientBrush{TPixel}.cs

@@ -0,0 +1,167 @@
+using System;
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// Gradient Brush with elliptic shape.
+    /// The ellipse is defined by a center point,
+    /// a point on the longest extension of the ellipse and
+    /// the ratio between longest and shortest extension.
+    /// </summary>
+    /// <typeparam name="TPixel">The Pixel format that is used.</typeparam>
+    public sealed class EllipticGradientBrush<TPixel> : GradientBrushBase<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        private readonly Point center;
+
+        private readonly Point referenceAxisEnd;
+
+        private readonly float axisRatio;
+
+        /// <inheritdoc cref="GradientBrushBase{TPixel}" />
+        /// <param name="center">The center of the elliptical gradient and 0 for the color stops.</param>
+        /// <param name="referenceAxisEnd">The end point of the reference axis of the ellipse.</param>
+        /// <param name="axisRatio">
+        ///   The ratio of the axis widths.
+        ///   The second axis' is perpendicular to the reference axis and
+        ///   it's length is the reference axis' length multiplied by this factor.
+        /// </param>
+        /// <param name="repetitionMode">Defines how the colors of the gradients are repeated.</param>
+        /// <param name="colorStops">the color stops as defined in base class.</param>
+        public EllipticGradientBrush(
+            Point center,
+            Point referenceAxisEnd,
+            float axisRatio,
+            GradientRepetitionMode repetitionMode,
+            params ColorStop<TPixel>[] colorStops)
+            : base(repetitionMode, colorStops)
+        {
+            this.center = center;
+            this.referenceAxisEnd = referenceAxisEnd;
+            this.axisRatio = axisRatio;
+        }
+
+        /// <inheritdoc cref="CreateApplicator" />
+        public override BrushApplicator<TPixel> CreateApplicator(
+            ImageFrame<TPixel> source,
+            RectangleF region,
+            GraphicsOptions options) =>
+            new RadialGradientBrushApplicator(
+                source,
+                options,
+                this.center,
+                this.referenceAxisEnd,
+                this.axisRatio,
+                this.ColorStops,
+                this.RepetitionMode);
+
+        /// <inheritdoc />
+        private sealed class RadialGradientBrushApplicator : GradientBrushApplicatorBase
+        {
+            private readonly Point center;
+
+            private readonly Point referenceAxisEnd;
+
+            private readonly float axisRatio;
+
+            private readonly double rotation;
+
+            private readonly float referenceRadius;
+
+            private readonly float secondRadius;
+
+            private readonly float cosRotation;
+
+            private readonly float sinRotation;
+
+            private readonly float secondRadiusSquared;
+
+            private readonly float referenceRadiusSquared;
+
+            /// <summary>
+            /// Initializes a new instance of the <see cref="RadialGradientBrushApplicator" /> class.
+            /// </summary>
+            /// <param name="target">The target image</param>
+            /// <param name="options">The options</param>
+            /// <param name="center">Center of the ellipse</param>
+            /// <param name="referenceAxisEnd">Point on one angular points of the ellipse.</param>
+            /// <param name="axisRatio">
+            /// Ratio of the axis length's. Used to determine the length of the second axis,
+            /// the first is defined by <see cref="center"/> and <see cref="referenceAxisEnd"/>.</param>
+            /// <param name="colorStops">Definition of colors</param>
+            /// <param name="repetitionMode">Defines how the gradient colors are repeated.</param>
+            public RadialGradientBrushApplicator(
+                ImageFrame<TPixel> target,
+                GraphicsOptions options,
+                Point center,
+                Point referenceAxisEnd,
+                float axisRatio,
+                ColorStop<TPixel>[] colorStops,
+                GradientRepetitionMode repetitionMode)
+                : base(target, options, colorStops, repetitionMode)
+            {
+                this.center = center;
+                this.referenceAxisEnd = referenceAxisEnd;
+                this.axisRatio = axisRatio;
+                this.rotation = this.AngleBetween(
+                    this.center,
+                    new PointF(this.center.X + 1, this.center.Y),
+                    this.referenceAxisEnd);
+                this.referenceRadius = this.DistanceBetween(this.center, this.referenceAxisEnd);
+                this.secondRadius = this.referenceRadius * this.axisRatio;
+
+                this.referenceRadiusSquared = this.referenceRadius * this.referenceRadius;
+                this.secondRadiusSquared = this.secondRadius * this.secondRadius;
+
+                this.sinRotation = (float)Math.Sin(this.rotation);
+                this.cosRotation = (float)Math.Cos(this.rotation);
+            }
+
+            /// <inheritdoc />
+            public override void Dispose()
+            {
+            }
+
+            /// <inheritdoc />
+            protected override float PositionOnGradient(int xt, int yt)
+            {
+                float x0 = xt - this.center.X;
+                float y0 = yt - this.center.Y;
+
+                float x = (x0 * this.cosRotation) - (y0 * this.sinRotation);
+                float y = (x0 * this.sinRotation) + (y0 * this.cosRotation);
+
+                float xSquared = x * x;
+                float ySquared = y * y;
+
+                var inBoundaryChecker = (xSquared / this.referenceRadiusSquared)
+                                        + (ySquared / this.secondRadiusSquared);
+
+                return inBoundaryChecker;
+            }
+
+            private float AngleBetween(PointF junction, PointF a, PointF b)
+            {
+                var vA = a - junction;
+                var vB = b - junction;
+                return (float)(Math.Atan2(vB.Y, vB.X)
+                       - Math.Atan2(vA.Y, vA.X));
+            }
+
+            private float DistanceBetween(
+                PointF p1,
+                PointF p2)
+            {
+                float dX = p1.X - p2.X;
+                float dXsquared = dX * dX;
+
+                float dY = p1.Y - p2.Y;
+                float dYsquared = dY * dY;
+                return (float)Math.Sqrt(dXsquared + dYsquared);
+            }
+        }
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/GradientBrushBase{TPixel}.cs

@@ -0,0 +1,174 @@
+using System;
+using System.Numerics;
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.PixelFormats.PixelBlenders;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// Base class for Gradient brushes
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format</typeparam>
+    public abstract class GradientBrushBase<TPixel> : IBrush<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <inheritdoc cref="IBrush{TPixel}"/>
+        /// <param name="repetitionMode">Defines how the colors are repeated beyond the interval [0..1]</param>
+        /// <param name="colorStops">The gradient colors.</param>
+        protected GradientBrushBase(
+            GradientRepetitionMode repetitionMode,
+            params ColorStop<TPixel>[] colorStops)
+        {
+            this.RepetitionMode = repetitionMode;
+            this.ColorStops = colorStops;
+        }
+
+        /// <summary>
+        /// Gets how the colors are repeated beyond the interval [0..1].
+        /// </summary>
+        protected GradientRepetitionMode RepetitionMode { get; }
+
+        /// <summary>
+        /// Gets the list of color stops for this gradient.
+        /// </summary>
+        protected ColorStop<TPixel>[] ColorStops { get; }
+
+        /// <inheritdoc cref="IBrush{TPixel}" />
+        public abstract BrushApplicator<TPixel> CreateApplicator(
+            ImageFrame<TPixel> source,
+            RectangleF region,
+            GraphicsOptions options);
+
+        /// <summary>
+        /// Base class for gradient brush applicators
+        /// </summary>
+        protected abstract class GradientBrushApplicatorBase : BrushApplicator<TPixel>
+        {
+            private readonly ColorStop<TPixel>[] colorStops;
+
+            private readonly GradientRepetitionMode repetitionMode;
+
+            /// <summary>
+            /// Initializes a new instance of the <see cref="GradientBrushApplicatorBase"/> class.
+            /// </summary>
+            /// <param name="target">The target.</param>
+            /// <param name="options">The options.</param>
+            /// <param name="colorStops">An array of color stops sorted by their position.</param>
+            /// <param name="repetitionMode">Defines if and how the gradient should be repeated.</param>
+            protected GradientBrushApplicatorBase(
+                ImageFrame<TPixel> target,
+                GraphicsOptions options,
+                ColorStop<TPixel>[] colorStops,
+                GradientRepetitionMode repetitionMode)
+                : base(target, options)
+            {
+                this.colorStops = colorStops; // TODO: requires colorStops to be sorted by position - should that be checked?
+                this.repetitionMode = repetitionMode;
+            }
+
+            /// <summary>
+            /// Base implementation of the indexer for gradients
+            /// (follows the facade pattern, using abstract methods)
+            /// </summary>
+            /// <param name="x">X coordinate of the Pixel.</param>
+            /// <param name="y">Y coordinate of the Pixel.</param>
+            internal override TPixel this[int x, int y]
+            {
+                get
+                {
+                    float positionOnCompleteGradient = this.PositionOnGradient(x, y);
+
+                    switch (this.repetitionMode)
+                    {
+                        case GradientRepetitionMode.None:
+                            // do nothing. The following could be done, but is not necessary:
+                            // onLocalGradient = Math.Min(0, Math.Max(1, onLocalGradient));
+                            break;
+                        case GradientRepetitionMode.Repeat:
+                            positionOnCompleteGradient = positionOnCompleteGradient % 1;
+                            break;
+                        case GradientRepetitionMode.Reflect:
+                            positionOnCompleteGradient = positionOnCompleteGradient % 2;
+                            if (positionOnCompleteGradient > 1)
+                            {
+                                positionOnCompleteGradient = 2 - positionOnCompleteGradient;
+                            }
+
+                            break;
+                        case GradientRepetitionMode.DontFill:
+                            if (positionOnCompleteGradient > 1 || positionOnCompleteGradient < 0)
+                            {
+                                return NamedColors<TPixel>.Transparent;
+                            }
+
+                            break;
+                        default:
+                            throw new ArgumentOutOfRangeException();
+                    }
+
+                    var (from, to) = this.GetGradientSegment(positionOnCompleteGradient);
+
+                    if (from.Color.Equals(to.Color))
+                    {
+                        return from.Color;
+                    }
+                    else
+                    {
+                        var fromAsVector = from.Color.ToVector4();
+                        var toAsVector = to.Color.ToVector4();
+                        float onLocalGradient = (positionOnCompleteGradient - from.Ratio) / to.Ratio;
+
+                        // TODO: this should be changeble for different gradienting functions
+                        Vector4 result = PorterDuffFunctions.Normal(
+                            fromAsVector,
+                            toAsVector,
+                            onLocalGradient);
+
+                        TPixel resultColor = default;
+                        resultColor.PackFromVector4(result);
+                        return resultColor;
+                    }
+                }
+            }
+
+            /// <summary>
+            /// calculates the position on the gradient for a given pixel.
+            /// This method is abstract as it's content depends on the shape of the gradient.
+            /// </summary>
+            /// <param name="x">The x coordinate of the pixel</param>
+            /// <param name="y">The y coordinate of the pixel</param>
+            /// <returns>
+            /// The position the given pixel has on the gradient.
+            /// The position is not bound to the [0..1] interval.
+            /// Values outside of that interval may be treated differently,
+            /// e.g. for the <see cref="GradientRepetitionMode" /> enum.
+            /// </returns>
+            protected abstract float PositionOnGradient(int x, int y);
+
+            private (ColorStop<TPixel> from, ColorStop<TPixel> to) GetGradientSegment(
+                float positionOnCompleteGradient)
+            {
+                var localGradientFrom = this.colorStops[0];
+                ColorStop<TPixel> localGradientTo = default;
+
+                // TODO: ensure colorStops has at least 2 items (technically 1 would be okay, but that's no gradient)
+                foreach (var colorStop in this.colorStops)
+                {
+                    localGradientTo = colorStop;
+
+                    if (colorStop.Ratio > positionOnCompleteGradient)
+                    {
+                        // we're done here, so break it!
+                        break;
+                    }
+
+                    localGradientFrom = localGradientTo;
+                }
+
+                return (localGradientFrom, localGradientTo);
+            }
+        }
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/GradientRepetitionMode.cs

@@ -0,0 +1,34 @@
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// Modes to repeat a gradient.
+    /// </summary>
+    public enum GradientRepetitionMode
+    {
+        /// <summary>
+        /// don't repeat, keep the color of start and end beyond those points stable.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Repeat the gradient.
+        /// If it's a black-white gradient, with Repeat it will be Black->{gray}->White|Black->{gray}->White|...
+        /// </summary>
+        Repeat,
+
+        /// <summary>
+        /// Reflect the gradient.
+        /// Similar to <see cref="Repeat"/>, but each other repetition uses inverse order of <see cref="ColorStop{TPixel}"/>s.
+        /// Used on a Black-White gradient, Reflect leads to Black->{gray}->White->{gray}->White...
+        /// </summary>
+        Reflect,
+
+        /// <summary>
+        /// With DontFill a gradient does not touch any pixel beyond it's borders.
+        /// For the <see cref="LinearGradientBrush{TPixel}" /> this is beyond the orthogonal through start and end,
+        /// TODO For the cref="PolygonalGradientBrush" it's outside the polygon,
+        /// For <see cref="RadialGradientBrush{TPixel}" /> and <see cref="EllipticGradientBrush{TPixel}" /> it's beyond 1.0.
+        /// </summary>
+        DontFill
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/LinearGradientBrush{TPixel}.cs

@@ -0,0 +1,152 @@
+using System;
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// Provides an implementation of a brush for painting linear gradients within areas.
+    /// Supported right now:
+    /// - a set of colors in relative distances to each other.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format</typeparam>
+    public sealed class LinearGradientBrush<TPixel> : GradientBrushBase<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        private readonly Point p1;
+
+        private readonly Point p2;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="LinearGradientBrush{TPixel}"/> class.
+        /// </summary>
+        /// <param name="p1">Start point</param>
+        /// <param name="p2">End point</param>
+        /// <param name="repetitionMode">defines how colors are repeated.</param>
+        /// <param name="colorStops"><inheritdoc /></param>
+        public LinearGradientBrush(
+            Point p1,
+            Point p2,
+            GradientRepetitionMode repetitionMode,
+            params ColorStop<TPixel>[] colorStops)
+            : base(repetitionMode, colorStops)
+        {
+            this.p1 = p1;
+            this.p2 = p2;
+        }
+
+        /// <inheritdoc />
+        public override BrushApplicator<TPixel> CreateApplicator(ImageFrame<TPixel> source, RectangleF region, GraphicsOptions options)
+            => new LinearGradientBrushApplicator(source, this.p1, this.p2, this.ColorStops, this.RepetitionMode, options);
+
+        /// <summary>
+        /// The linear gradient brush applicator.
+        /// </summary>
+        private sealed class LinearGradientBrushApplicator : GradientBrushApplicatorBase
+        {
+            private readonly Point start;
+
+            private readonly Point end;
+
+            /// <summary>
+            /// the vector along the gradient, x component
+            /// </summary>
+            private readonly float alongX;
+
+            /// <summary>
+            /// the vector along the gradient, y component
+            /// </summary>
+            private readonly float alongY;
+
+            /// <summary>
+            /// the vector perpendicular to the gradient, y component
+            /// </summary>
+            private readonly float acrossY;
+
+            /// <summary>
+            /// the vector perpendicular to the gradient, x component
+            /// </summary>
+            private readonly float acrossX;
+
+            /// <summary>
+            /// the result of <see cref="alongX"/>^2 + <see cref="alongY"/>^2
+            /// </summary>
+            private readonly float alongsSquared;
+
+            /// <summary>
+            /// the length of the defined gradient (between source and end)
+            /// </summary>
+            private readonly float length;
+
+            /// <summary>
+            /// Initializes a new instance of the <see cref="LinearGradientBrushApplicator" /> class.
+            /// </summary>
+            /// <param name="source">The source</param>
+            /// <param name="start">start point of the gradient</param>
+            /// <param name="end">end point of the gradient</param>
+            /// <param name="colorStops">tuple list of colors and their respective position between 0 and 1 on the line</param>
+            /// <param name="repetitionMode">defines how the gradient colors are repeated.</param>
+            /// <param name="options">the graphics options</param>
+            public LinearGradientBrushApplicator(
+                ImageFrame<TPixel> source,
+                Point start,
+                Point end,
+                ColorStop<TPixel>[] colorStops,
+                GradientRepetitionMode repetitionMode,
+                GraphicsOptions options)
+                : base(source, options, colorStops, repetitionMode)
+            {
+                this.start = start;
+                this.end = end;
+
+                // the along vector:
+                this.alongX = this.end.X - this.start.X;
+                this.alongY = this.end.Y - this.start.Y;
+
+                // the cross vector:
+                this.acrossX = this.alongY;
+                this.acrossY = -this.alongX;
+
+                // some helpers:
+                this.alongsSquared = (this.alongX * this.alongX) + (this.alongY * this.alongY);
+                this.length = (float)Math.Sqrt(this.alongsSquared);
+            }
+
+            protected override float PositionOnGradient(int x, int y)
+            {
+                if (this.acrossX == 0)
+                {
+                    return (x - this.start.X) / (float)(this.end.X - this.start.X);
+                }
+                else if (this.acrossY == 0)
+                {
+                    return (y - this.start.Y) / (float)(this.end.Y - this.start.Y);
+                }
+                else
+                {
+                    float deltaX = x - this.start.X;
+                    float deltaY = y - this.start.Y;
+                    float k = ((this.alongY * deltaX) - (this.alongX * deltaY)) / this.alongsSquared;
+
+                    // point on the line:
+                    float x4 = x - (k * this.alongY);
+                    float y4 = y + (k * this.alongX);
+
+                    // get distance from (x4,y4) to start
+                    float distance = (float)Math.Sqrt(
+                        Math.Pow(x4 - this.start.X, 2)
+                        + Math.Pow(y4 - this.start.Y, 2));
+
+                    // get and return ratio
+                    float ratio = distance / this.length;
+                    return ratio;
+                }
+            }
+
+            public override void Dispose()
+            {
+            }
+        }
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/GradientBrushes/RadialGradientBrush{TPixel}.cs

@@ -0,0 +1,102 @@
+using System;
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes
+{
+    /// <summary>
+    /// A Circular Gradient Brush, defined by center point and radius.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    public sealed class RadialGradientBrush<TPixel> : GradientBrushBase<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        private readonly Point center;
+
+        private readonly float radius;
+
+        /// <inheritdoc cref="GradientBrushBase{TPixel}" />
+        /// <param name="center">The center of the circular gradient and 0 for the color stops.</param>
+        /// <param name="radius">The radius of the circular gradient and 1 for the color stops.</param>
+        /// <param name="repetitionMode">Defines how the colors in the gradient are repeated.</param>
+        /// <param name="colorStops">the color stops as defined in base class.</param>
+        public RadialGradientBrush(
+            Point center,
+            float radius,
+            GradientRepetitionMode repetitionMode,
+            params ColorStop<TPixel>[] colorStops)
+            : base(repetitionMode, colorStops)
+        {
+            this.center = center;
+            this.radius = radius;
+        }
+
+        /// <inheritdoc cref="CreateApplicator" />
+        public override BrushApplicator<TPixel> CreateApplicator(
+            ImageFrame<TPixel> source,
+            RectangleF region,
+            GraphicsOptions options) =>
+            new RadialGradientBrushApplicator(
+                source,
+                options,
+                this.center,
+                this.radius,
+                this.ColorStops,
+                this.RepetitionMode);
+
+        /// <inheritdoc />
+        private sealed class RadialGradientBrushApplicator : GradientBrushApplicatorBase
+        {
+            private readonly Point center;
+
+            private readonly float radius;
+
+            /// <summary>
+            /// Initializes a new instance of the <see cref="RadialGradientBrushApplicator" /> class.
+            /// </summary>
+            /// <param name="target">The target image</param>
+            /// <param name="options">The options.</param>
+            /// <param name="center">Center point of the gradient.</param>
+            /// <param name="radius">Radius of the gradient.</param>
+            /// <param name="colorStops">Definition of colors.</param>
+            /// <param name="repetitionMode">How the colors are repeated beyond the first gradient.</param>
+            public RadialGradientBrushApplicator(
+                ImageFrame<TPixel> target,
+                GraphicsOptions options,
+                Point center,
+                float radius,
+                ColorStop<TPixel>[] colorStops,
+                GradientRepetitionMode repetitionMode)
+                : base(target, options, colorStops, repetitionMode)
+            {
+                this.center = center;
+                this.radius = radius;
+            }
+
+            /// <inheritdoc cref="Dispose" />
+            public override void Dispose()
+            {
+            }
+
+            /// <summary>
+            /// As this is a circular gradient, the position on the gradient is based on
+            /// the distance of the point to the center.
+            /// </summary>
+            /// <param name="x">The X coordinate of the target pixel.</param>
+            /// <param name="y">The Y coordinate of the target pixel.</param>
+            /// <returns>the position on the color gradient.</returns>
+            protected override float PositionOnGradient(int x, int y)
+            {
+                float distance = (float)Math.Sqrt(Math.Pow(this.center.X - x, 2) + Math.Pow(this.center.Y - y, 2));
+                return distance / this.radius;
+            }
+
+            internal override void Apply(Span<float> scanline, int x, int y)
+            {
+                // TODO: each row is symmetric across center, so we can calculate half of it and mirror it to improve performance.
+                base.Apply(scanline, x, y);
+            }
+        }
+    }
+}

src/ImageSharp.Drawing/Processing/Drawing/Brushes/SolidBrush{TPixel}.cs

@@ -90,16 +90,23 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Brushes
 
                 MemoryManager memoryManager = this.Target.MemoryManager;
 
-                using (IBuffer<float> amountBuffer = memoryManager.Allocate<float>(scanline.Length))
+                if (this.Options.BlendPercentage == 1f)
                 {
-                    Span<float> amountSpan = amountBuffer.Span;
-
-                    for (int i = 0; i < scanline.Length; i++)
+                    this.Blender.Blend(memoryManager, destinationRow, destinationRow, this.Colors.Span, scanline);
+                }
+                else
+                {
+                    using (IBuffer<float> amountBuffer = memoryManager.Allocate<float>(scanline.Length))
                     {
-                        amountSpan[i] = scanline[i] * this.Options.BlendPercentage;
-                    }
+                        Span<float> amountSpan = amountBuffer.Span;
+
+                        for (int i = 0; i < scanline.Length; i++)
+                        {
+                            amountSpan[i] = scanline[i] * this.Options.BlendPercentage;
+                        }
 
-                    this.Blender.Blend(memoryManager, destinationRow, destinationRow, this.Colors.Span, amountSpan);
+                        this.Blender.Blend(memoryManager, destinationRow, destinationRow, this.Colors.Span, amountSpan);
+                    }
                 }
             }
         }

src/ImageSharp.Drawing/Processing/Drawing/FillPathExtensions.cs

@@ -14,7 +14,7 @@ namespace SixLabors.ImageSharp.Processing.Drawing
     public static class FillPathExtensions
     {
         /// <summary>
-        /// Flood fills the image in the shape of the provided polygon with the specified brush..
+        /// Flood fills the image in the shape of the provided polygon with the specified brush.
         /// </summary>
         /// <typeparam name="TPixel">The type of the color.</typeparam>
         /// <param name="source">The image this method extends.</param>

src/ImageSharp.Drawing/Processing/Drawing/Processors/FillProcessor.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Threading.Tasks;
+using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Drawing.Brushes;
@@ -49,39 +50,66 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Processors
             int minY = Math.Max(0, startY);
             int maxY = Math.Min(source.Height, endY);
 
-            // Reset offset if necessary.
-            if (minX > 0)
-            {
-                startX = 0;
-            }
-
-            if (minY > 0)
-            {
-                startY = 0;
-            }
-
             int width = maxX - minX;
 
-            using (IBuffer<float> amount = source.MemoryManager.Allocate<float>(width))
-            using (BrushApplicator<TPixel> applicator = this.brush.CreateApplicator(
-                source,
-                sourceRectangle,
-                this.options))
+            // If there's no reason for blending, then avoid it.
+            if (this.IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush))
             {
-                amount.Span.Fill(this.options.BlendPercentage);
-
                 Parallel.For(
                     minY,
                     maxY,
                     configuration.ParallelOptions,
                     y =>
-                        {
-                            int offsetY = y - startY;
-                            int offsetX = minX - startX;
+                    {
+                        source.GetPixelRowSpan(y).Slice(minX, width).Fill(solidBrush.Color);
+                    });
+            }
+            else
+            {
+                // Reset offset if necessary.
+                if (minX > 0)
+                {
+                    startX = 0;
+                }
+
+                if (minY > 0)
+                {
+                    startY = 0;
+                }
+
+                using (IBuffer<float> amount = source.MemoryManager.Allocate<float>(width))
+                using (BrushApplicator<TPixel> applicator = this.brush.CreateApplicator(
+                    source,
+                    sourceRectangle,
+                    this.options))
+                {
+                    amount.Span.Fill(1f);
+
+                    Parallel.For(
+                        minY,
+                        maxY,
+                        configuration.ParallelOptions,
+                        y =>
+                            {
+                                int offsetY = y - startY;
+                                int offsetX = minX - startX;
 
-                            applicator.Apply(amount.Span, offsetX, offsetY);
-                        });
+                                applicator.Apply(amount.Span, offsetX, offsetY);
+                            });
+                }
             }
         }
+
+        private bool IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush)
+        {
+            solidBrush = this.brush as SolidBrush<TPixel>;
+
+            return solidBrush != null
+                   && ((this.options.BlenderMode == PixelBlenderMode.Normal && this.options.BlendPercentage == 1f
+                                                                            && solidBrush.Color.ToVector4().W == 1f)
+                       || (this.options.BlenderMode == PixelBlenderMode.Over && this.options.BlendPercentage == 1f
+                                                                             && solidBrush.Color.ToVector4().W == 1f)
+                       || (this.options.BlenderMode == PixelBlenderMode.Src));
+        }
     }
 }

src/ImageSharp.Drawing/Processing/Drawing/Processors/FillRegionProcessor.cs

@@ -100,6 +100,8 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Processors
                 using (BasicArrayBuffer<float> scanline = source.MemoryManager.AllocateFake<float>(scanlineWidth))
                 {
                     bool scanlineDirty = true;
+                    float subpixelFraction = 1f / subpixelCount;
+                    float subpixelFractionPoint = subpixelFraction / subpixelCount;
                     for (int y = minY; y < maxY; y++)
                     {
                         if (scanlineDirty)
@@ -113,9 +115,8 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Processors
                             scanlineDirty = false;
                         }
 
-                        float subpixelFraction = 1f / subpixelCount;
-                        float subpixelFractionPoint = subpixelFraction / subpixelCount;
-                        for (float subPixel = (float)y; subPixel < y + 1; subPixel += subpixelFraction)
+                        float yPlusOne = y + 1;
+                        for (float subPixel = (float)y; subPixel < yPlusOne; subPixel += subpixelFraction)
                         {
                             int pointsFound = region.Scan(subPixel + offset, buffer.Array, 0);
                             if (pointsFound == 0)
@@ -197,8 +198,7 @@ namespace SixLabors.ImageSharp.Processing.Drawing.Processors
 
         private static void QuickSort(Span<float> data)
         {
-            int hi = Math.Min(data.Length - 1, data.Length - 1);
-            QuickSort(data, 0, hi);
+            QuickSort(data, 0, data.Length - 1);
         }
 
         private static void QuickSort(Span<float> data, int lo, int hi)

src/ImageSharp/Advanced/IConfigurable.cs

@@ -4,7 +4,7 @@
 namespace SixLabors.ImageSharp.Advanced
 {
     /// <summary>
-    /// Encapsulates the properties for configuration
+    /// Encapsulates the properties for configuration.
     /// </summary>
     internal interface IConfigurable
     {

src/ImageSharp/Common/Extensions/ByteExtensions.cs

@@ -1,55 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.PixelFormats;
-
-namespace SixLabors.ImageSharp
-{
-    /// <summary>
-    /// Extension methods for the <see cref="byte"/> struct buffers.
-    /// </summary>
-    internal static class ByteExtensions
-    {
-        /// <summary>
-        /// Returns a reference to the given position of the array unsafe casted to <see cref="ImageSharp.PixelFormats.Rgb24"/>.
-        /// </summary>
-        /// <param name="bytes">The byte array.</param>
-        /// <param name="offset">The offset in bytes.</param>
-        /// <returns>The <see cref="ImageSharp.PixelFormats.Rgb24"/> reference at the given offset.</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ref Rgb24 GetRgb24(this byte[] bytes, int offset)
-        {
-            DebugGuard.MustBeLessThan(offset + 2, bytes.Length, nameof(offset));
-
-            return ref Unsafe.As<byte, Rgb24>(ref bytes[offset]);
-        }
-
-        /// <summary>
-        /// Returns a reference to the given position of the span unsafe casted to <see cref="ImageSharp.PixelFormats.Rgb24"/>.
-        /// </summary>
-        /// <param name="bytes">The byte span.</param>
-        /// <param name="offset">The offset in bytes.</param>
-        /// <returns>The <see cref="ImageSharp.PixelFormats.Rgb24"/> reference at the given offset.</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ref Rgb24 GetRgb24(this Span<byte> bytes, int offset)
-        {
-            DebugGuard.MustBeLessThan(offset + 2, bytes.Length, nameof(offset));
-
-            return ref Unsafe.As<byte, Rgb24>(ref bytes[offset]);
-        }
-
-        /// <summary>
-        ///  Returns a reference to the given position of the buffer pointed by `baseRef` unsafe casted to <see cref="ImageSharp.PixelFormats.Rgb24"/>.
-        /// </summary>
-        /// <param name="baseRef">A reference to the beginning of the buffer</param>
-        /// <param name="offset">The offset in bytes.</param>
-        /// <returns>The <see cref="ImageSharp.PixelFormats.Rgb24"/> reference at the given offset.</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ref Rgb24 GetRgb24(ref byte baseRef, int offset)
-        {
-            return ref Unsafe.As<byte, Rgb24>(ref Unsafe.Add(ref baseRef, offset));
-        }
-    }
-}

src/ImageSharp/Common/Helpers/Guard.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
 
 namespace SixLabors.ImageSharp
 {
@@ -15,78 +14,62 @@ namespace SixLabors.ImageSharp
     internal static class Guard
     {
         /// <summary>
-        /// Verifies, that the method parameter with specified object value is not null
-        /// and throws an exception if it is found to be so.
+        /// Ensures that the value is not null.
         /// </summary>
-        /// <param name="target">The target object, which cannot be null.</param>
+        /// <param name="value">The target object, which cannot be null.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
-        /// <param name="message">The error message, if any to add to the exception.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="target"/> is null</exception>
-        public static void NotNull(object target, string parameterName, string message = "")
+        /// <exception cref="ArgumentNullException"><paramref name="value"/> is null</exception>
+        public static void NotNull(object value, string parameterName)
         {
-            if (target == null)
+            if (value == null)
             {
-                if (!string.IsNullOrWhiteSpace(message))
-                {
-                    throw new ArgumentNullException(parameterName, message);
-                }
-
                 throw new ArgumentNullException(parameterName);
             }
         }
 
         /// <summary>
-        /// Verifies, that the string method parameter with specified object value and message
-        /// is not null, not empty and does not contain only blanks and throws an exception
-        /// if the object is null.
+        /// Ensures that the target value is not null, empty, or whitespace.
         /// </summary>
-        /// <param name="target">The target string, which should be checked against being null or empty.</param>
+        /// <param name="value">The target string, which should be checked against being null or empty.</param>
         /// <param name="parameterName">Name of the parameter.</param>
-        /// <param name="message">The error message, if any to add to the exception.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="target"/> is null.</exception>
-        /// <exception cref="ArgumentException"><paramref name="target"/> is empty or contains only blanks.</exception>
-        public static void NotNullOrEmpty(string target, string parameterName, string message = "")
+        /// <exception cref="ArgumentNullException"><paramref name="value"/> is null.</exception>
+        /// <exception cref="ArgumentException"><paramref name="value"/> is empty or contains only blanks.</exception>
+        public static void NotNullOrWhiteSpace(string value, string parameterName)
         {
-            NotNull(target, parameterName, message);
-
-            if (string.IsNullOrWhiteSpace(target))
+            if (value == null)
             {
-                if (!string.IsNullOrWhiteSpace(message))
-                {
-                    throw new ArgumentException(message, parameterName);
-                }
+                throw new ArgumentNullException(parameterName);
+            }
 
-                throw new ArgumentException("Value cannot be null or empty and cannot contain only blanks.", parameterName);
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                throw new ArgumentException("Must not be empty or whitespace.", parameterName);
             }
         }
 
         /// <summary>
-        /// Verifies, that the enumeration is not null and not empty.
+        /// Ensures that the enumeration is not null or empty.
         /// </summary>
-        /// <typeparam name="T">The type of objects in the <paramref name="target"/></typeparam>
-        /// <param name="target">The target enumeration, which should be checked against being null or empty.</param>
+        /// <typeparam name="T">The type of objects in the <paramref name="value"/></typeparam>
+        /// <param name="value">The target enumeration, which should be checked against being null or empty.</param>
         /// <param name="parameterName">Name of the parameter.</param>
-        /// <param name="message">The error message, if any to add to the exception.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="target"/> is null.</exception>
-        /// <exception cref="ArgumentException"><paramref name="target"/> is empty.</exception>
-        public static void NotNullOrEmpty<T>(IEnumerable<T> target, string parameterName, string message = "")
+        /// <exception cref="ArgumentNullException"><paramref name="value"/> is null.</exception>
+        /// <exception cref="ArgumentException"><paramref name="value"/> is empty.</exception>
+        public static void NotNullOrEmpty<T>(ICollection<T> value, string parameterName)
         {
-            NotNull(target, parameterName, message);
-
-            if (!target.Any())
+            if (value == null)
             {
-                if (!string.IsNullOrWhiteSpace(message))
-                {
-                    throw new ArgumentException(message, parameterName);
-                }
+                throw new ArgumentNullException(parameterName);
+            }
 
-                throw new ArgumentException("Value cannot be empty.", parameterName);
+            if (value.Count == 0)
+            {
+                throw new ArgumentException("Must not be empty.", parameterName);
             }
         }
 
         /// <summary>
-        /// Verifies that the specified value is less than a maximum value
-        /// and throws an exception if it is not.
+        /// Ensures that the specified value is less than a maximum value.
         /// </summary>
         /// <param name="value">The target value, which should be validated.</param>
         /// <param name="max">The maximum value.</param>
@@ -191,15 +174,9 @@ namespace SixLabors.ImageSharp
         /// Verifies, that the method parameter with specified target value is true
         /// and throws an exception if it is found to be so.
         /// </summary>
-        /// <param name="target">
-        /// The target value, which cannot be false.
-        /// </param>
-        /// <param name="parameterName">
-        /// The name of the parameter that is to be checked.
-        /// </param>
-        /// <param name="message">
-        /// The error message, if any to add to the exception.
-        /// </param>
+        /// <param name="target">The target value, which cannot be false.</param>
+        /// <param name="parameterName">The name of the parameter that is to be checked.</param>
+        /// <param name="message">The error message, if any to add to the exception.</param>
         /// <exception cref="ArgumentException">
         /// <paramref name="target"/> is false
         /// </exception>

src/ImageSharp/Configuration.cs

@@ -18,7 +18,7 @@ using SixLabors.ImageSharp.Processing;
 namespace SixLabors.ImageSharp
 {
     /// <summary>
-    /// Provides initialization code which allows extending the library.
+    /// Provides configuration code which allows altering default behaviour or extending the library.
     /// </summary>
     public sealed class Configuration
     {

src/ImageSharp/Formats/Gif/GifDecoderCore.cs

@@ -39,11 +39,6 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// </summary>
         private IManagedByteBuffer globalColorTable;
 
-        /// <summary>
-        /// The global color table length
-        /// </summary>
-        private int globalColorTableLength;
-
         /// <summary>
         /// The area to restore.
         /// </summary>
@@ -333,8 +328,8 @@ namespace SixLabors.ImageSharp.Formats.Gif
                 indices = this.configuration.MemoryManager.AllocateManagedByteBuffer(imageDescriptor.Width * imageDescriptor.Height, true);
 
                 this.ReadFrameIndices(imageDescriptor, indices.Span);
-                IManagedByteBuffer colorTable = localColorTable ?? this.globalColorTable;
-                this.ReadFrameColors(ref image, ref previousFrame, indices.Span, colorTable.Span, imageDescriptor);
+                ReadOnlySpan<Rgb24> colorTable = MemoryMarshal.Cast<byte, Rgb24>((localColorTable ?? this.globalColorTable).Span);
+                this.ReadFrameColors(ref image, ref previousFrame, indices.Span, colorTable, imageDescriptor);
 
                 // Skip any remaining blocks
                 this.Skip(0);
@@ -370,7 +365,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// <param name="indices">The indexed pixels.</param>
         /// <param name="colorTable">The color table containing the available colors.</param>
         /// <param name="descriptor">The <see cref="GifImageDescriptor"/></param>
-        private void ReadFrameColors<TPixel>(ref Image<TPixel> image, ref ImageFrame<TPixel> previousFrame, Span<byte> indices, Span<byte> colorTable, in GifImageDescriptor descriptor)
+        private void ReadFrameColors<TPixel>(ref Image<TPixel> image, ref ImageFrame<TPixel> previousFrame, Span<byte> indices, ReadOnlySpan<Rgb24> colorTable, in GifImageDescriptor descriptor)
             where TPixel : struct, IPixel<TPixel>
         {
             ref byte indicesRef = ref MemoryMarshal.GetReference(indices);
@@ -458,11 +453,8 @@ namespace SixLabors.ImageSharp.Formats.Gif
                     if (this.graphicsControlExtension.TransparencyFlag == false ||
                         this.graphicsControlExtension.TransparencyIndex != index)
                     {
-                        int indexOffset = index * 3;
-
                         ref TPixel pixel = ref Unsafe.Add(ref rowRef, x);
-                        rgba.Rgb = colorTable.GetRgb24(indexOffset);
-
+                        rgba.Rgb = colorTable[index];
                         pixel.PackFromRgba32(rgba);
                     }
 
@@ -534,12 +526,12 @@ namespace SixLabors.ImageSharp.Formats.Gif
 
             if (this.logicalScreenDescriptor.GlobalColorTableFlag)
             {
-                this.globalColorTableLength = this.logicalScreenDescriptor.GlobalColorTableSize * 3;
+                int globalColorTableLength = this.logicalScreenDescriptor.GlobalColorTableSize * 3;
 
-                this.globalColorTable = this.MemoryManager.AllocateManagedByteBuffer(this.globalColorTableLength, true);
+                this.globalColorTable = this.MemoryManager.AllocateManagedByteBuffer(globalColorTableLength, true);
 
-                // Read the global color table from the stream
-                stream.Read(this.globalColorTable.Array, 0, this.globalColorTableLength);
+                // Read the global color table data from the stream
+                stream.Read(this.globalColorTable.Array, 0, globalColorTableLength);
             }
         }
     }

src/ImageSharp/Formats/ImageFormatManager.cs

@@ -85,6 +85,13 @@ namespace SixLabors.ImageSharp.Formats
         /// <returns>The <see cref="IImageFormat"/> if found otherwise null</returns>
         public IImageFormat FindFormatByFileExtension(string extension)
         {
+            Guard.NotNullOrWhiteSpace(extension, nameof(extension));
+
+            if (extension[0] == '.')
+            {
+                extension = extension.Substring(1);
+            }
+
             return this.imageFormats.FirstOrDefault(x => x.FileExtensions.Contains(extension, StringComparer.OrdinalIgnoreCase));
         }
 

src/ImageSharp/Formats/Jpeg/Common/Block8x8.cs → src/ImageSharp/Formats/Jpeg/Components/Block8x8.cs

@@ -7,7 +7,7 @@ using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Text;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// Represents a Jpeg block with <see cref="short"/> coefficiens.

src/ImageSharp/Formats/Jpeg/Common/Block8x8F.CopyTo.cs → src/ImageSharp/Formats/Jpeg/Components/Block8x8F.CopyTo.cs

@@ -3,10 +3,11 @@
 
 using System.Numerics;
 using System.Runtime.CompilerServices;
+
 using SixLabors.ImageSharp.Memory;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     internal partial struct Block8x8F
     {

src/ImageSharp/Formats/Jpeg/Common/Block8x8F.Generated.cs → src/ImageSharp/Formats/Jpeg/Components/Block8x8F.Generated.cs

@@ -5,7 +5,7 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 
 // <auto-generated />
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
 	internal partial struct Block8x8F
     {

src/ImageSharp/Formats/Jpeg/Common/Block8x8F.Generated.tt → src/ImageSharp/Formats/Jpeg/Components/Block8x8F.Generated.tt

@@ -18,7 +18,7 @@ using System.Runtime.CompilerServices;
 <#
 char[] coordz = {'X', 'Y', 'Z', 'W'};
 #>
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
 	internal partial struct Block8x8F
     {

src/ImageSharp/Formats/Jpeg/Common/Block8x8F.cs → src/ImageSharp/Formats/Jpeg/Components/Block8x8F.cs

@@ -9,7 +9,7 @@ using System.Runtime.InteropServices;
 using System.Text;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// Represents a Jpeg block with <see cref="float"/> coefficients.
@@ -100,7 +100,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
             {
                 float val = result[i];
                 val /= value;
-                result[i] = (float)val;
+                result[i] = val;
             }
 
             return result;
@@ -113,7 +113,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
             {
                 float val = result[i];
                 val += value;
-                result[i] = (float)val;
+                result[i] = val;
             }
 
             return result;
@@ -126,7 +126,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
             {
                 float val = result[i];
                 val -= value;
-                result[i] = (float)val;
+                result[i] = val;
             }
 
             return result;
@@ -153,7 +153,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
         public void Clear()
         {
             // The cheapest way to do this in C#:
-            this = default(Block8x8F);
+            this = default;
         }
 
         /// <summary>

src/ImageSharp/Formats/Jpeg/Common/Decoder/AdobeMarker.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/AdobeMarker.cs

@@ -4,7 +4,7 @@
 using System;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Provides information about the Adobe marker segment.
@@ -78,7 +78,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
                 return true;
             }
 
-            marker = default(AdobeMarker);
+            marker = default;
             return false;
         }
 

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromCmyk.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmyk.cs

@@ -4,18 +4,18 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromCmyk : ColorConverters.JpegColorConverter
+        internal class FromCmyk : JpegColorConverter
         {
             public FromCmyk()
                 : base(JpegColorSpace.Cmyk)
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 // TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
                 ReadOnlySpan<float> cVals = values.Component0;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromGrayScale.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromGrayScale.cs

@@ -4,18 +4,18 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromGrayscale : ColorConverters.JpegColorConverter
+        internal class FromGrayscale : JpegColorConverter
         {
             public FromGrayscale()
                 : base(JpegColorSpace.Grayscale)
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 // TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
                 ReadOnlySpan<float> yVals = values.Component0;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromRgb.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromRgb.cs

@@ -4,18 +4,18 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromRgb : ColorConverters.JpegColorConverter
+        internal class FromRgb : JpegColorConverter
         {
             public FromRgb()
                 : base(JpegColorSpace.RGB)
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 // TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
                 ReadOnlySpan<float> rVals = values.Component0;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromYCbCrBasic.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrBasic.cs

@@ -4,18 +4,18 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromYCbCrBasic : ColorConverters.JpegColorConverter
+        internal class FromYCbCrBasic : JpegColorConverter
         {
             public FromYCbCrBasic()
                 : base(JpegColorSpace.YCbCr)
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 ConvertCore(values, result);
             }

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimd.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimd.cs

@@ -5,20 +5,21 @@ using System;
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+
 using SixLabors.ImageSharp.Common.Tuples;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromYCbCrSimd : ColorConverters.JpegColorConverter
+        internal class FromYCbCrSimd : JpegColorConverter
         {
             public FromYCbCrSimd()
                 : base(JpegColorSpace.YCbCr)
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 int remainder = result.Length % 8;
                 int simdCount = result.Length - remainder;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimdAvx2.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimdAvx2.cs

@@ -5,14 +5,15 @@ using System;
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+
 using SixLabors.ImageSharp.Common.Tuples;
 
 // ReSharper disable ImpureMethodCallOnReadonlyValueField
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal class FromYCbCrSimdAvx2 : ColorConverters.JpegColorConverter
+        internal class FromYCbCrSimdAvx2 : JpegColorConverter
         {
             public FromYCbCrSimdAvx2()
                 : base(JpegColorSpace.YCbCr)
@@ -21,7 +22,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
 
             public static bool IsAvailable => Vector.IsHardwareAccelerated && SimdUtils.IsAvx2CompatibleArchitecture;
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 int remainder = result.Length % 8;
                 int simdCount = result.Length - remainder;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.FromYccK.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYccK.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
@@ -15,7 +15,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
             {
             }
 
-            public override void ConvertToRGBA(ComponentValues values, Span<Vector4> result)
+            public override void ConvertToRgba(ComponentValues values, Span<Vector4> result)
             {
                 // TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
                 ReadOnlySpan<float> yVals = values.Component0;

src/ImageSharp/Formats/Jpeg/Common/Decoder/ColorConverters/JpegColorConverter.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.cs

@@ -5,10 +5,11 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Numerics;
+
 using SixLabors.ImageSharp.Common.Tuples;
 using SixLabors.ImageSharp.Memory;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     /// <summary>
     /// Encapsulates the conversion of Jpeg channels to RGBA values packed in <see cref="Vector4"/> buffer.
@@ -55,13 +56,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.ColorConverters
         /// </summary>
         /// <param name="values">The input as a stack-only <see cref="ComponentValues"/> struct</param>
         /// <param name="result">The destination buffer of <see cref="Vector4"/> values</param>
-        public abstract void ConvertToRGBA(ComponentValues values, Span<Vector4> result);
+        public abstract void ConvertToRgba(ComponentValues values, Span<Vector4> result);
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverter"/> for the YCbCr colorspace that matches the current CPU architecture.
         /// </summary>
         private static JpegColorConverter GetYCbCrConverter() =>
-            FromYCbCrSimdAvx2.IsAvailable ? (JpegColorConverter)new FromYCbCrSimdAvx2() : new FromYCbCrSimd();
+            JpegColorConverter.FromYCbCrSimdAvx2.IsAvailable ? (JpegColorConverter)new JpegColorConverter.FromYCbCrSimdAvx2() : new JpegColorConverter.FromYCbCrSimd();
 
         /// <summary>
         /// A stack-only struct to reference the input buffers using <see cref="ReadOnlySpan{T}"/>-s.

src/ImageSharp/Formats/Jpeg/Common/Decoder/IJpegComponent.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/IJpegComponent.cs

@@ -1,7 +1,10 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Common interface to represent raw Jpeg components.

src/ImageSharp/Formats/Jpeg/Common/Decoder/IRawJpegData.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/IRawJpegData.cs

@@ -1,13 +1,16 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Collections.Generic;
 
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <inheritdoc />
     /// <summary>
-    /// Represents decompressed, unprocessed jpeg data with spectral space <see cref="T:SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder.IJpegComponent" />-s.
+    /// Represents decompressed, unprocessed jpeg data with spectral space <see cref="IJpegComponent" />-s.
     /// </summary>
     internal interface IRawJpegData : IDisposable
     {

src/ImageSharp/Formats/Jpeg/Common/Decoder/JFifMarker.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/JFifMarker.cs

@@ -3,7 +3,7 @@
 
 using System;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Provides information about the JFIF marker segment

src/ImageSharp/Formats/Jpeg/Common/Decoder/JpegBlockPostProcessor.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/JpegBlockPostProcessor.cs

@@ -2,10 +2,11 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System.Runtime.InteropServices;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Encapsulates the implementation of processing "raw" <see cref="IBuffer{T}"/>-s into Jpeg image channels.

src/ImageSharp/Formats/Jpeg/Common/Decoder/JpegColorSpace.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/JpegColorSpace.cs

@@ -1,4 +1,7 @@
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Identifies the colorspace of a Jpeg image

src/ImageSharp/Formats/Jpeg/Common/Decoder/JpegComponentPostProcessor.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/JpegComponentPostProcessor.cs

@@ -1,8 +1,12 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Encapsulates postprocessing data for one component for <see cref="JpegImagePostProcessor"/>.

src/ImageSharp/Formats/Jpeg/Common/Decoder/JpegImagePostProcessor.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/JpegImagePostProcessor.cs

@@ -1,12 +1,18 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Linq;
 using System.Numerics;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+using JpegColorConverter = SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters.JpegColorConverter;
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Encapsulates the execution od post-processing algorithms to be applied on a <see cref="IRawJpegData"/> to produce a valid <see cref="Image{TPixel}"/>: <br/>
@@ -36,9 +42,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
         private readonly IBuffer<Vector4> rgbaBuffer;
 
         /// <summary>
-        /// The <see cref="ColorConverters.JpegColorConverter"/> corresponding to the current <see cref="JpegColorSpace"/> determined by <see cref="IRawJpegData.ColorSpace"/>.
+        /// The <see cref="JpegColorConverter"/> corresponding to the current <see cref="JpegColorSpace"/> determined by <see cref="IRawJpegData.ColorSpace"/>.
         /// </summary>
-        private ColorConverters.JpegColorConverter colorConverter;
+        private readonly JpegColorConverter colorConverter;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="JpegImagePostProcessor"/> class.
@@ -54,7 +60,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
 
             this.ComponentProcessors = rawJpeg.Components.Select(c => new JpegComponentPostProcessor(memoryManager, this, c)).ToArray();
             this.rgbaBuffer = memoryManager.Allocate<Vector4>(rawJpeg.ImageSizeInPixels.Width);
-            this.colorConverter = ColorConverters.JpegColorConverter.GetConverter(rawJpeg.ColorSpace);
+            this.colorConverter = JpegColorConverter.GetConverter(rawJpeg.ColorSpace);
         }
 
         /// <summary>
@@ -148,8 +154,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
             {
                 int y = yy - this.PixelRowCounter;
 
-                var values = new ColorConverters.JpegColorConverter.ComponentValues(buffers, y);
-                this.colorConverter.ConvertToRGBA(values, this.rgbaBuffer.Span);
+                var values = new JpegColorConverter.ComponentValues(buffers, y);
+                this.colorConverter.ConvertToRgba(values, this.rgbaBuffer.Span);
 
                 Span<TPixel> destRow = destination.GetPixelRowSpan(yy);
 

src/ImageSharp/Formats/Jpeg/Common/Decoder/ProfileResolver.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ProfileResolver.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Text;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
     /// <summary>
     /// Provides methods for identifying metadata and color profiles within jpeg images.

src/ImageSharp/Formats/Jpeg/GolangPort/Components/BlockQuad.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/BlockQuad.cs

@@ -1,18 +1,16 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using Block8x8F = SixLabors.ImageSharp.Formats.Jpeg.Common.Block8x8F;
-
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
-    /// Poor man's stackalloc: Contains a value-type <see cref="float"/> buffer sized for 4 <see cref="Common.Block8x8F"/> instances.
+    /// Poor man's stackalloc: Contains a value-type <see cref="float"/> buffer sized for 4 <see cref="Block8x8F"/> instances.
     /// Useful for decoder/encoder operations allocating a block for each Jpeg component.
     /// </summary>
     internal unsafe struct BlockQuad
     {
         /// <summary>
-        /// The value-type <see cref="float"/> buffer sized for 4 <see cref="Common.Block8x8F"/> instances.
+        /// The value-type <see cref="float"/> buffer sized for 4 <see cref="Block8x8F"/> instances.
         /// </summary>
         public fixed float Data[4 * Block8x8F.Size];
     }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/HuffIndex.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/HuffIndex.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     /// Enumerates the Huffman tables

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/HuffmanLut.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/HuffmanLut.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     /// A compiled look-up table representation of a huffmanSpec.

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/HuffmanSpec.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/HuffmanSpec.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     ///     The Huffman encoding specifications.

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/QuantIndex.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/QuantIndex.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     ///     Enumerates the quantization tables

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/RgbToYCbCrTables.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/RgbToYCbCrTables.cs

@@ -3,9 +3,7 @@
 
 using System.Runtime.CompilerServices;
 
-using SixLabors.ImageSharp.Memory;
-
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     /// Provides 8-bit lookup tables for converting from Rgb to YCbCr colorspace.
@@ -68,7 +66,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
         /// <returns>The intialized <see cref="RgbToYCbCrTables"/></returns>
         public static RgbToYCbCrTables Create()
         {
-            RgbToYCbCrTables tables = default(RgbToYCbCrTables);
+            RgbToYCbCrTables tables = default;
 
             for (int i = 0; i <= 255; i++)
             {
@@ -123,11 +121,5 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
         {
             return (int)((x * (1L << ScaleBits)) + 0.5F);
         }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static int RightShift(int x)
-        {
-            return x >> ScaleBits;
-        }
     }
 }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/YCbCrForwardConverter{TPixel}.cs → src/ImageSharp/Formats/Jpeg/Components/Encoder/YCbCrForwardConverter{TPixel}.cs

@@ -1,10 +1,10 @@
 using System;
 using System.Runtime.CompilerServices;
+
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
 using SixLabors.ImageSharp.PixelFormats;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
 {
     /// <summary>
     /// On-stack worker struct to efficiently encapsulate the TPixel -> Rgb24 -> YCbCr conversion chain of 8x8 pixel blocks.

src/ImageSharp/Formats/Jpeg/Common/FastFloatingPointDCT.cs → src/ImageSharp/Formats/Jpeg/Components/FastFloatingPointDCT.cs

@@ -5,7 +5,7 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// Contains inaccurate, but fast forward and inverse DCT implementations.

src/ImageSharp/Formats/Jpeg/Common/GenericBlock8x8.Generated.cs → src/ImageSharp/Formats/Jpeg/Components/GenericBlock8x8.Generated.cs

@@ -1,11 +1,8 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Numerics;
-using System.Runtime.CompilerServices;
-
 // <auto-generated />
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
 	internal unsafe partial struct GenericBlock8x8<T>
     {

src/ImageSharp/Formats/Jpeg/Common/GenericBlock8x8.Generated.tt → src/ImageSharp/Formats/Jpeg/Components/GenericBlock8x8.Generated.tt

@@ -11,11 +11,8 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Numerics;
-using System.Runtime.CompilerServices;
-
 // <auto-generated />
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
 	internal unsafe partial struct GenericBlock8x8<T>
     {

src/ImageSharp/Formats/Jpeg/Common/GenericBlock8x8.cs → src/ImageSharp/Formats/Jpeg/Components/GenericBlock8x8.cs

@@ -1,13 +1,16 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Primitives;
 
 // ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// A generic 8x8 block implementation, useful for manipulating custom 8x8 pixel data.
@@ -18,8 +21,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
     {
         public const int Size = 64;
 
-        public const int SizeInBytes = Size * 3;
-
         /// <summary>
         /// FOR TESTING ONLY!
         /// Gets or sets a <see cref="Rgb24"/> value at the given index

src/ImageSharp/Formats/Jpeg/Common/SizeExtensions.cs → src/ImageSharp/Formats/Jpeg/Components/SizeExtensions.cs

@@ -3,9 +3,10 @@
 
 using System;
 using System.Numerics;
+
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// Extension methods for <see cref="Size"/>

src/ImageSharp/Formats/Jpeg/Common/ZigZag.cs → src/ImageSharp/Formats/Jpeg/Components/ZigZag.cs

@@ -1,10 +1,11 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components
 {
     /// <summary>
     /// Holds the Jpeg UnZig array in a value/stack type.

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/Bits.cs

@@ -38,7 +38,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void EnsureNBits(int n, ref InputProcessor inputProcessor)
         {
-            OrigDecoderErrorCode errorCode = this.EnsureNBitsUnsafe(n, ref inputProcessor);
+            GolangDecoderErrorCode errorCode = this.EnsureNBitsUnsafe(n, ref inputProcessor);
             errorCode.EnsureNoError();
         }
 
@@ -46,17 +46,17 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// Reads bytes from the byte buffer to ensure that bits.UnreadBits is at
         /// least n. For best performance (avoiding function calls inside hot loops),
         /// the caller is the one responsible for first checking that bits.UnreadBits < n.
-        /// This method does not throw. Returns <see cref="OrigDecoderErrorCode"/> instead.
+        /// This method does not throw. Returns <see cref="GolangDecoderErrorCode"/> instead.
         /// </summary>
         /// <param name="n">The number of bits to ensure.</param>
         /// <param name="inputProcessor">The <see cref="InputProcessor"/></param>
         /// <returns>Error code</returns>
-        public OrigDecoderErrorCode EnsureNBitsUnsafe(int n, ref InputProcessor inputProcessor)
+        public GolangDecoderErrorCode EnsureNBitsUnsafe(int n, ref InputProcessor inputProcessor)
         {
             while (true)
             {
-                OrigDecoderErrorCode errorCode = this.EnsureBitsStepImpl(ref inputProcessor);
-                if (errorCode != OrigDecoderErrorCode.NoError || this.UnreadBits >= n)
+                GolangDecoderErrorCode errorCode = this.EnsureBitsStepImpl(ref inputProcessor);
+                if (errorCode != GolangDecoderErrorCode.NoError || this.UnreadBits >= n)
                 {
                     return errorCode;
                 }
@@ -67,8 +67,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// Unrolled version of <see cref="EnsureNBitsUnsafe"/> for n==8
         /// </summary>
         /// <param name="inputProcessor">The <see cref="InputProcessor"/></param>
-        /// <returns>A <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode Ensure8BitsUnsafe(ref InputProcessor inputProcessor)
+        /// <returns>A <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode Ensure8BitsUnsafe(ref InputProcessor inputProcessor)
         {
             return this.EnsureBitsStepImpl(ref inputProcessor);
         }
@@ -77,8 +77,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// Unrolled version of <see cref="EnsureNBitsUnsafe"/> for n==1
         /// </summary>
         /// <param name="inputProcessor">The <see cref="InputProcessor"/></param>
-        /// <returns>A <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode Ensure1BitUnsafe(ref InputProcessor inputProcessor)
+        /// <returns>A <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode Ensure1BitUnsafe(ref InputProcessor inputProcessor)
         {
             return this.EnsureBitsStepImpl(ref inputProcessor);
         }
@@ -92,7 +92,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public int ReceiveExtend(int t, ref InputProcessor inputProcessor)
         {
-            OrigDecoderErrorCode errorCode = this.ReceiveExtendUnsafe(t, ref inputProcessor, out int x);
+            GolangDecoderErrorCode errorCode = this.ReceiveExtendUnsafe(t, ref inputProcessor, out int x);
             errorCode.EnsureNoError();
             return x;
         }
@@ -103,13 +103,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// <param name="t">Byte</param>
         /// <param name="inputProcessor">The <see cref="InputProcessor"/></param>
         /// <param name="x">Read bits value</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode ReceiveExtendUnsafe(int t, ref InputProcessor inputProcessor, out int x)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode ReceiveExtendUnsafe(int t, ref InputProcessor inputProcessor, out int x)
         {
             if (this.UnreadBits < t)
             {
-                OrigDecoderErrorCode errorCode = this.EnsureNBitsUnsafe(t, ref inputProcessor);
-                if (errorCode != OrigDecoderErrorCode.NoError)
+                GolangDecoderErrorCode errorCode = this.EnsureNBitsUnsafe(t, ref inputProcessor);
+                if (errorCode != GolangDecoderErrorCode.NoError)
                 {
                     x = int.MaxValue;
                     return errorCode;
@@ -126,14 +126,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 x += ((-1) << t) + 1;
             }
 
-            return OrigDecoderErrorCode.NoError;
+            return GolangDecoderErrorCode.NoError;
         }
 
-        private OrigDecoderErrorCode EnsureBitsStepImpl(ref InputProcessor inputProcessor)
+        private GolangDecoderErrorCode EnsureBitsStepImpl(ref InputProcessor inputProcessor)
         {
-            OrigDecoderErrorCode errorCode = inputProcessor.Bytes.ReadByteStuffedByteUnsafe(inputProcessor.InputStream, out int c);
+            GolangDecoderErrorCode errorCode = inputProcessor.Bytes.ReadByteStuffedByteUnsafe(inputProcessor.InputStream, out int c);
 
-            if (errorCode != OrigDecoderErrorCode.NoError)
+            if (errorCode != GolangDecoderErrorCode.NoError)
             {
                 return errorCode;
             }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/Bytes.cs

@@ -77,8 +77,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="inputStream">Input stream</param>
         /// <param name="x">The result byte as <see cref="int"/></param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode ReadByteStuffedByteUnsafe(Stream inputStream, out int x)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode ReadByteStuffedByteUnsafe(Stream inputStream, out int x)
         {
             // Take the fast path if bytes.buf contains at least two bytes.
             if (this.I + 2 <= this.J)
@@ -86,50 +86,50 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 x = this.BufferAsInt[this.I];
                 this.I++;
                 this.UnreadableBytes = 1;
-                if (x != OrigJpegConstants.Markers.XFFInt)
+                if (x != JpegConstants.Markers.XFFInt)
                 {
-                    return OrigDecoderErrorCode.NoError;
+                    return GolangDecoderErrorCode.NoError;
                 }
 
                 if (this.BufferAsInt[this.I] != 0x00)
                 {
-                    return OrigDecoderErrorCode.MissingFF00;
+                    return GolangDecoderErrorCode.MissingFF00;
                 }
 
                 this.I++;
                 this.UnreadableBytes = 2;
-                x = OrigJpegConstants.Markers.XFF;
-                return OrigDecoderErrorCode.NoError;
+                x = JpegConstants.Markers.XFF;
+                return GolangDecoderErrorCode.NoError;
             }
 
             this.UnreadableBytes = 0;
 
-            OrigDecoderErrorCode errorCode = this.ReadByteAsIntUnsafe(inputStream, out x);
+            GolangDecoderErrorCode errorCode = this.ReadByteAsIntUnsafe(inputStream, out x);
             this.UnreadableBytes = 1;
-            if (errorCode != OrigDecoderErrorCode.NoError)
+            if (errorCode != GolangDecoderErrorCode.NoError)
             {
                 return errorCode;
             }
 
-            if (x != OrigJpegConstants.Markers.XFF)
+            if (x != JpegConstants.Markers.XFF)
             {
-                return OrigDecoderErrorCode.NoError;
+                return GolangDecoderErrorCode.NoError;
             }
 
             errorCode = this.ReadByteAsIntUnsafe(inputStream, out x);
             this.UnreadableBytes = 2;
-            if (errorCode != OrigDecoderErrorCode.NoError)
+            if (errorCode != GolangDecoderErrorCode.NoError)
             {
                 return errorCode;
             }
 
             if (x != 0x00)
             {
-                return OrigDecoderErrorCode.MissingFF00;
+                return GolangDecoderErrorCode.MissingFF00;
             }
 
-            x = OrigJpegConstants.Markers.XFF;
-            return OrigDecoderErrorCode.NoError;
+            x = JpegConstants.Markers.XFF;
+            return GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
@@ -140,25 +140,25 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public byte ReadByte(Stream inputStream)
         {
-            OrigDecoderErrorCode errorCode = this.ReadByteUnsafe(inputStream, out byte result);
+            GolangDecoderErrorCode errorCode = this.ReadByteUnsafe(inputStream, out byte result);
             errorCode.EnsureNoError();
             return result;
         }
 
         /// <summary>
         /// Extracts the next byte, whether buffered or not buffered into the result out parameter. It does not care about byte stuffing.
-        /// This method does not throw on format error, it returns a <see cref="OrigDecoderErrorCode"/> instead.
+        /// This method does not throw on format error, it returns a <see cref="GolangDecoderErrorCode"/> instead.
         /// </summary>
         /// <param name="inputStream">Input stream</param>
         /// <param name="result">The result <see cref="byte"/> as out parameter</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode ReadByteUnsafe(Stream inputStream, out byte result)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode ReadByteUnsafe(Stream inputStream, out byte result)
         {
-            OrigDecoderErrorCode errorCode = OrigDecoderErrorCode.NoError;
+            GolangDecoderErrorCode errorCode = GolangDecoderErrorCode.NoError;
             while (this.I == this.J)
             {
                 errorCode = this.FillUnsafe(inputStream);
-                if (errorCode != OrigDecoderErrorCode.NoError)
+                if (errorCode != GolangDecoderErrorCode.NoError)
                 {
                     result = 0;
                     return errorCode;
@@ -176,15 +176,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="inputStream">The input stream</param>
         /// <param name="result">The result <see cref="int"/></param>
-        /// <returns>A <see cref="OrigDecoderErrorCode"/></returns>
+        /// <returns>A <see cref="GolangDecoderErrorCode"/></returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public OrigDecoderErrorCode ReadByteAsIntUnsafe(Stream inputStream, out int result)
+        public GolangDecoderErrorCode ReadByteAsIntUnsafe(Stream inputStream, out int result)
         {
-            OrigDecoderErrorCode errorCode = OrigDecoderErrorCode.NoError;
+            GolangDecoderErrorCode errorCode = GolangDecoderErrorCode.NoError;
             while (this.I == this.J)
             {
                 errorCode = this.FillUnsafe(inputStream);
-                if (errorCode != OrigDecoderErrorCode.NoError)
+                if (errorCode != GolangDecoderErrorCode.NoError)
                 {
                     result = 0;
                     return errorCode;
@@ -206,18 +206,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void Fill(Stream inputStream)
         {
-            OrigDecoderErrorCode errorCode = this.FillUnsafe(inputStream);
+            GolangDecoderErrorCode errorCode = this.FillUnsafe(inputStream);
             errorCode.EnsureNoError();
         }
 
         /// <summary>
         /// Fills up the bytes buffer from the underlying stream.
         /// It should only be called when there are no unread bytes in bytes.
-        /// This method does not throw <see cref="EOFException"/>, returns a <see cref="OrigDecoderErrorCode"/> instead!
+        /// This method does not throw <see cref="EOFException"/>, returns a <see cref="GolangDecoderErrorCode"/> instead!
         /// </summary>
         /// <param name="inputStream">Input stream</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode FillUnsafe(Stream inputStream)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode FillUnsafe(Stream inputStream)
         {
             if (this.I != this.J)
             {
@@ -239,7 +239,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             int n = inputStream.Read(this.Buffer, this.J, this.Buffer.Length - this.J);
             if (n == 0)
             {
-                return OrigDecoderErrorCode.UnexpectedEndOfStream;
+                return GolangDecoderErrorCode.UnexpectedEndOfStream;
             }
 
             this.J += n;
@@ -249,7 +249,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 this.BufferAsInt[i] = this.Buffer[i];
             }
 
-            return OrigDecoderErrorCode.NoError;
+            return GolangDecoderErrorCode.NoError;
         }
     }
 }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/DecoderThrowHelper.cs

@@ -12,22 +12,22 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     internal static class DecoderThrowHelper
     {
         /// <summary>
-        /// Throws an exception that belongs to the given <see cref="OrigDecoderErrorCode"/>
+        /// Throws an exception that belongs to the given <see cref="GolangDecoderErrorCode"/>
         /// </summary>
-        /// <param name="errorCode">The <see cref="OrigDecoderErrorCode"/></param>
+        /// <param name="errorCode">The <see cref="GolangDecoderErrorCode"/></param>
         [MethodImpl(MethodImplOptions.NoInlining)]
-        public static void ThrowExceptionForErrorCode(this OrigDecoderErrorCode errorCode)
+        public static void ThrowExceptionForErrorCode(this GolangDecoderErrorCode errorCode)
         {
             // REMARK: If this method throws for an image that is expected to be decodable,
             // consider using the ***Unsafe variant of the parsing method that asks for ThrowExceptionForErrorCode()
             // then verify the error code + implement fallback logic manually!
             switch (errorCode)
             {
-                case OrigDecoderErrorCode.NoError:
+                case GolangDecoderErrorCode.NoError:
                     throw new ArgumentException("ThrowExceptionForErrorCode() called with NoError!", nameof(errorCode));
-                case OrigDecoderErrorCode.MissingFF00:
+                case GolangDecoderErrorCode.MissingFF00:
                     throw new MissingFF00Exception();
-                case OrigDecoderErrorCode.UnexpectedEndOfStream:
+                case GolangDecoderErrorCode.UnexpectedEndOfStream:
                     throw new EOFException();
                 default:
                     throw new ArgumentOutOfRangeException(nameof(errorCode), errorCode, null);
@@ -35,26 +35,26 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         }
 
         /// <summary>
-        /// Throws an exception if the given <see cref="OrigDecoderErrorCode"/> defines an error.
+        /// Throws an exception if the given <see cref="GolangDecoderErrorCode"/> defines an error.
         /// </summary>
-        /// <param name="errorCode">The <see cref="OrigDecoderErrorCode"/></param>
+        /// <param name="errorCode">The <see cref="GolangDecoderErrorCode"/></param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void EnsureNoError(this OrigDecoderErrorCode errorCode)
+        public static void EnsureNoError(this GolangDecoderErrorCode errorCode)
         {
-            if (errorCode != OrigDecoderErrorCode.NoError)
+            if (errorCode != GolangDecoderErrorCode.NoError)
             {
                 ThrowExceptionForErrorCode(errorCode);
             }
         }
 
         /// <summary>
-        /// Throws an exception if the given <see cref="OrigDecoderErrorCode"/> is <see cref="OrigDecoderErrorCode.UnexpectedEndOfStream"/>.
+        /// Throws an exception if the given <see cref="GolangDecoderErrorCode"/> is <see cref="GolangDecoderErrorCode.UnexpectedEndOfStream"/>.
         /// </summary>
-        /// <param name="errorCode">The <see cref="OrigDecoderErrorCode"/></param>
+        /// <param name="errorCode">The <see cref="GolangDecoderErrorCode"/></param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void EnsureNoEOF(this OrigDecoderErrorCode errorCode)
+        public static void EnsureNoEOF(this GolangDecoderErrorCode errorCode)
         {
-            if (errorCode == OrigDecoderErrorCode.UnexpectedEndOfStream)
+            if (errorCode == GolangDecoderErrorCode.UnexpectedEndOfStream)
             {
                 errorCode.ThrowExceptionForErrorCode();
             }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponent.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangComponent.cs

@@ -3,8 +3,9 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.Primitives;
 
@@ -14,9 +15,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     /// <summary>
     /// Represents a single color component
     /// </summary>
-    internal class OrigComponent : IDisposable, IJpegComponent
+    internal class GolangComponent : IDisposable, IJpegComponent
     {
-        public OrigComponent(byte identifier, int index)
+        public GolangComponent(byte identifier, int index)
         {
             this.Identifier = identifier;
             this.Index = index;
@@ -56,8 +57,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// Initializes <see cref="SpectralBlocks"/>
         /// </summary>
         /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
-        /// <param name="decoder">The <see cref="OrigJpegDecoderCore"/> instance</param>
-        public void InitializeDerivedData(MemoryManager memoryManager, OrigJpegDecoderCore decoder)
+        /// <param name="decoder">The <see cref="GolangJpegDecoderCore"/> instance</param>
+        public void InitializeDerivedData(MemoryManager memoryManager, GolangJpegDecoderCore decoder)
         {
             // For 4-component images (either CMYK or YCbCrK), we only support two
             // hv vectors: [0x11 0x11 0x11 0x11] and [0x22 0x11 0x11 0x22].
@@ -76,7 +77,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             }
             else
             {
-                OrigComponent c0 = decoder.Components[0];
+                GolangComponent c0 = decoder.Components[0];
                 this.SubSamplingDivisors = c0.SamplingFactors.DivideBy(this.SamplingFactors);
             }
 
@@ -86,8 +87,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// <summary>
         /// Initializes all component data except <see cref="SpectralBlocks"/>.
         /// </summary>
-        /// <param name="decoder">The <see cref="OrigJpegDecoderCore"/> instance</param>
-        public void InitializeCoreData(OrigJpegDecoderCore decoder)
+        /// <param name="decoder">The <see cref="GolangJpegDecoderCore"/> instance</param>
+        public void InitializeCoreData(GolangJpegDecoderCore decoder)
         {
             // Section B.2.2 states that "the value of C_i shall be different from
             // the values of C_1 through C_(i-1)".
@@ -102,7 +103,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             }
 
             this.QuantizationTableIndex = decoder.Temp[8 + (3 * i)];
-            if (this.QuantizationTableIndex > OrigJpegDecoderCore.MaxTq)
+            if (this.QuantizationTableIndex > GolangJpegDecoderCore.MaxTq)
             {
                 throw new ImageFormatException("Bad Tq value");
             }
@@ -246,7 +247,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 
         public void Dispose()
         {
-            this.SpectralBlocks.Dispose();
+            this.SpectralBlocks?.Dispose();
         }
     }
 }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponentScan.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangComponentScan.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     /// Represents a component scan
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    internal struct OrigComponentScan
+    internal struct GolangComponentScan
     {
         /// <summary>
         /// Gets or sets the component index.

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigDecoderErrorCode.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangDecoderErrorCode.cs

@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     /// <summary>
     /// Represents "recoverable" decoder errors.
     /// </summary>
-    internal enum OrigDecoderErrorCode
+    internal enum GolangDecoderErrorCode
     {
         /// <summary>
         /// NoError

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigHuffmanTree.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangHuffmanTree.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
-using System.Buffers;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -12,7 +10,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     /// Represents a Huffman tree
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    internal unsafe struct OrigHuffmanTree
+    internal unsafe struct GolangHuffmanTree
     {
         /// <summary>
         /// The index of the AC table row
@@ -95,12 +93,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         public FixedInt32Buffer16 Indices;
 
         /// <summary>
-        /// Creates and initializes an array of <see cref="OrigHuffmanTree" /> instances of size <see cref="NumberOfTrees" />
+        /// Creates and initializes an array of <see cref="GolangHuffmanTree" /> instances of size <see cref="NumberOfTrees" />
         /// </summary>
-        /// <returns>An array of <see cref="OrigHuffmanTree" /> instances representing the Huffman tables</returns>
-        public static OrigHuffmanTree[] CreateHuffmanTrees()
+        /// <returns>An array of <see cref="GolangHuffmanTree" /> instances representing the Huffman tables</returns>
+        public static GolangHuffmanTree[] CreateHuffmanTrees()
         {
-            return new OrigHuffmanTree[NumberOfTrees];
+            return new GolangHuffmanTree[NumberOfTrees];
         }
 
         /// <summary>

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigJpegScanDecoder.ComputationData.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangJpegScanDecoder.ComputationData.cs

@@ -2,14 +2,15 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 {
     /// <content>
     /// Conains the definition of <see cref="ComputationData"/>
     /// </content>
-    internal unsafe partial struct OrigJpegScanDecoder
+    internal unsafe partial struct GolangJpegScanDecoder
     {
         /// <summary>
         /// Holds the "large" data blocks needed for computations.
@@ -28,14 +29,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             public ZigZag Unzig;
 
             /// <summary>
-            /// The buffer storing the <see cref="OrigComponentScan"/>-s for each component
+            /// The buffer storing the <see cref="GolangComponentScan"/>-s for each component
             /// </summary>
-            public fixed byte ScanData[3 * OrigJpegDecoderCore.MaxComponents];
+            public fixed byte ScanData[3 * GolangJpegDecoderCore.MaxComponents];
 
             /// <summary>
             /// The DC values for each component
             /// </summary>
-            public fixed int Dc[OrigJpegDecoderCore.MaxComponents];
+            public fixed int Dc[GolangJpegDecoderCore.MaxComponents];
 
             /// <summary>
             /// Creates and initializes a new <see cref="ComputationData"/> instance

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigJpegScanDecoder.DataPointers.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangJpegScanDecoder.DataPointers.cs

@@ -1,14 +1,14 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 {
     /// <content>
     /// Conains the definition of <see cref="DataPointers"/>
     /// </content>
-    internal unsafe partial struct OrigJpegScanDecoder
+    internal unsafe partial struct GolangJpegScanDecoder
     {
         /// <summary>
         /// Contains pointers to the memory regions of <see cref="ComputationData"/> so they can be easily passed around to pointer based utility methods of <see cref="Block8x8F"/>
@@ -28,7 +28,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             /// <summary>
             /// Pointer to <see cref="ComputationData.ScanData"/> as Scan*
             /// </summary>
-            public OrigComponentScan* ComponentScan;
+            public GolangComponentScan* ComponentScan;
 
             /// <summary>
             /// Pointer to <see cref="ComputationData.Dc"/>
@@ -43,7 +43,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             {
                 this.Block = &basePtr->Block;
                 this.Unzig = basePtr->Unzig.Data;
-                this.ComponentScan = (OrigComponentScan*)basePtr->ScanData;
+                this.ComponentScan = (GolangComponentScan*)basePtr->ScanData;
                 this.Dc = basePtr->Dc;
             }
         }

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigJpegScanDecoder.cs → src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/GolangJpegScanDecoder.cs

@@ -3,9 +3,8 @@
 
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
-using SixLabors.ImageSharp.Memory;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
 
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
@@ -29,7 +28,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
     /// For baseline JPEGs, these parameters are hard-coded to 0/63/0/0.
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    internal unsafe partial struct OrigJpegScanDecoder
+    internal unsafe partial struct GolangJpegScanDecoder
     {
         // The JpegScanDecoder members should be ordered in a way that results in optimal memory layout.
 #pragma warning disable SA1202 // ElementsMustBeOrderedByAccess
@@ -110,12 +109,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         private byte expectedRst;
 
         /// <summary>
-        /// Initializes a default-constructed <see cref="OrigJpegScanDecoder"/> instance for reading data from <see cref="OrigJpegDecoderCore"/>-s stream.
+        /// Initializes a default-constructed <see cref="GolangJpegScanDecoder"/> instance for reading data from <see cref="GolangJpegDecoderCore"/>-s stream.
         /// </summary>
-        /// <param name="p">Pointer to <see cref="OrigJpegScanDecoder"/> on the stack</param>
-        /// <param name="decoder">The <see cref="OrigJpegDecoderCore"/> instance</param>
+        /// <param name="p">Pointer to <see cref="GolangJpegScanDecoder"/> on the stack</param>
+        /// <param name="decoder">The <see cref="GolangJpegDecoderCore"/> instance</param>
         /// <param name="remaining">The remaining bytes in the segment block.</param>
-        public static void InitStreamReading(OrigJpegScanDecoder* p, OrigJpegDecoderCore decoder, int remaining)
+        public static void InitStreamReading(GolangJpegScanDecoder* p, GolangJpegDecoderCore decoder, int remaining)
         {
             p->data = ComputationData.Create();
             p->pointers = new DataPointers(&p->data);
@@ -123,8 +122,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         }
 
         /// <summary>
-        /// Read Huffman data from Jpeg scans in <see cref="OrigJpegDecoderCore.InputStream"/>,
-        /// and decode it as <see cref="Block8x8"/> into <see cref="OrigComponent.SpectralBlocks"/>.
+        /// Read Huffman data from Jpeg scans in <see cref="GolangJpegDecoderCore.InputStream"/>,
+        /// and decode it as <see cref="Block8x8"/> into <see cref="GolangComponent.SpectralBlocks"/>.
         ///
         /// The blocks are traversed one MCU at a time. For 4:2:0 chroma
         /// subsampling, there are four Y 8x8 blocks in every 16x16 MCU.
@@ -149,14 +148,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// 0 1 2
         /// 3 4 5
         /// </summary>
-        /// <param name="decoder">The <see cref="OrigJpegDecoderCore"/> instance</param>
-        public void DecodeBlocks(OrigJpegDecoderCore decoder)
+        /// <param name="decoder">The <see cref="GolangJpegDecoderCore"/> instance</param>
+        public void DecodeBlocks(GolangJpegDecoderCore decoder)
         {
             decoder.InputProcessor.ResetErrorState();
 
             this.blockCounter = 0;
             this.mcuCounter = 0;
-            this.expectedRst = OrigJpegConstants.Markers.RST0;
+            this.expectedRst = JpegConstants.Markers.RST0;
 
             for (int my = 0; my < decoder.MCUCountY; my++)
             {
@@ -177,12 +176,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             }
         }
 
-        private void DecodeBlocksAtMcuIndex(OrigJpegDecoderCore decoder, int mx, int my)
+        private void DecodeBlocksAtMcuIndex(GolangJpegDecoderCore decoder, int mx, int my)
         {
             for (int scanIndex = 0; scanIndex < this.componentScanCount; scanIndex++)
             {
                 this.ComponentIndex = this.pointers.ComponentScan[scanIndex].ComponentIndex;
-                OrigComponent component = decoder.Components[this.ComponentIndex];
+                GolangComponent component = decoder.Components[this.ComponentIndex];
 
                 this.hi = component.HorizontalSamplingFactor;
                 int vi = component.VerticalSamplingFactor;
@@ -223,7 +222,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             }
         }
 
-        private void ProcessRSTMarker(OrigJpegDecoderCore decoder)
+        private void ProcessRSTMarker(GolangJpegDecoderCore decoder)
         {
             // Attempt to look for RST[0-7] markers to resynchronize from corrupt input.
             if (!decoder.InputProcessor.ReachedEOF)
@@ -262,15 +261,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                     }
 
                     this.expectedRst++;
-                    if (this.expectedRst == OrigJpegConstants.Markers.RST7 + 1)
+                    if (this.expectedRst == JpegConstants.Markers.RST7 + 1)
                     {
-                        this.expectedRst = OrigJpegConstants.Markers.RST0;
+                        this.expectedRst = JpegConstants.Markers.RST0;
                     }
                 }
             }
         }
 
-        private void Reset(OrigJpegDecoderCore decoder)
+        private void Reset(GolangJpegDecoderCore decoder)
         {
             decoder.InputProcessor.ResetHuffmanDecoder();
 
@@ -285,15 +284,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         private void ResetDcValues()
         {
-            Unsafe.InitBlock(this.pointers.Dc, default(byte), sizeof(int) * OrigJpegDecoderCore.MaxComponents);
+            Unsafe.InitBlock(this.pointers.Dc, default, sizeof(int) * GolangJpegDecoderCore.MaxComponents);
         }
 
         /// <summary>
         /// The implementation part of <see cref="InitStreamReading"/> as an instance method.
         /// </summary>
-        /// <param name="decoder">The <see cref="OrigJpegDecoderCore"/></param>
+        /// <param name="decoder">The <see cref="GolangJpegDecoderCore"/></param>
         /// <param name="remaining">The remaining bytes</param>
-        private void InitStreamReadingImpl(OrigJpegDecoderCore decoder, int remaining)
+        private void InitStreamReadingImpl(GolangJpegDecoderCore decoder, int remaining)
         {
             if (decoder.ComponentCount == 0)
             {
@@ -360,10 +359,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="decoder">The decoder</param>
         /// <param name="scanIndex">The index of the scan</param>
-        private void DecodeBlock(OrigJpegDecoderCore decoder, int scanIndex)
+        private void DecodeBlock(GolangJpegDecoderCore decoder, int scanIndex)
         {
             Block8x8* b = this.pointers.Block;
-            int huffmannIdx = (OrigHuffmanTree.AcTableIndex * OrigHuffmanTree.ThRowSize) + this.pointers.ComponentScan[scanIndex].AcTableSelector;
+            int huffmannIdx = (GolangHuffmanTree.AcTableIndex * GolangHuffmanTree.ThRowSize) + this.pointers.ComponentScan[scanIndex].AcTableSelector;
             if (this.ah != 0)
             {
                 this.Refine(ref decoder.InputProcessor, ref decoder.HuffmanTrees[huffmannIdx], 1 << this.al);
@@ -377,7 +376,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                     zig++;
 
                     // Decode the DC coefficient, as specified in section F.2.2.1.
-                    int huffmanIndex = (OrigHuffmanTree.DcTableIndex * OrigHuffmanTree.ThRowSize) + this.pointers.ComponentScan[scanIndex].DcTableSelector;
+                    int huffmanIndex = (GolangHuffmanTree.DcTableIndex * GolangHuffmanTree.ThRowSize) + this.pointers.ComponentScan[scanIndex].DcTableSelector;
                     decoder.InputProcessor.DecodeHuffmanUnsafe(
                             ref decoder.HuffmanTrees[huffmanIndex],
                             out int value);
@@ -467,7 +466,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         private void DecodeEobRun(int count, ref InputProcessor processor)
         {
             processor.DecodeBitsUnsafe(count, out int bitsResult);
-            if (processor.LastErrorCode != OrigDecoderErrorCode.NoError)
+            if (processor.LastErrorCode != GolangDecoderErrorCode.NoError)
             {
                 return;
             }
@@ -475,7 +474,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             this.eobRun |= bitsResult;
         }
 
-        private void InitComponentScan(OrigJpegDecoderCore decoder, int i, ref OrigComponentScan currentComponentScan, ref int totalHv)
+        private void InitComponentScan(GolangJpegDecoderCore decoder, int i, ref GolangComponentScan currentComponentScan, ref int totalHv)
         {
             // Component selector.
             int cs = decoder.Temp[1 + (2 * i)];
@@ -500,11 +499,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         }
 
         private void ProcessComponentImpl(
-            OrigJpegDecoderCore decoder,
+            GolangJpegDecoderCore decoder,
             int i,
-            ref OrigComponentScan currentComponentScan,
+            ref GolangComponentScan currentComponentScan,
             ref int totalHv,
-            OrigComponent currentComponent)
+            GolangComponent currentComponent)
         {
             // Section B.2.3 states that "the value of Cs_j shall be different from
             // the values of Cs_1 through Cs_(j-1)". Since we have previously
@@ -522,13 +521,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             totalHv += currentComponent.HorizontalSamplingFactor * currentComponent.VerticalSamplingFactor;
 
             currentComponentScan.DcTableSelector = (byte)(decoder.Temp[2 + (2 * i)] >> 4);
-            if (currentComponentScan.DcTableSelector > OrigHuffmanTree.MaxTh)
+            if (currentComponentScan.DcTableSelector > GolangHuffmanTree.MaxTh)
             {
                 throw new ImageFormatException("Bad DC table selector value");
             }
 
             currentComponentScan.AcTableSelector = (byte)(decoder.Temp[2 + (2 * i)] & 0x0f);
-            if (currentComponentScan.AcTableSelector > OrigHuffmanTree.MaxTh)
+            if (currentComponentScan.AcTableSelector > GolangHuffmanTree.MaxTh)
             {
                 throw new ImageFormatException("Bad AC table selector  value");
             }
@@ -540,7 +539,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// <param name="bp">The <see cref="InputProcessor"/> instance</param>
         /// <param name="h">The Huffman tree</param>
         /// <param name="delta">The low transform offset</param>
-        private void Refine(ref InputProcessor bp, ref OrigHuffmanTree h, int delta)
+        private void Refine(ref InputProcessor bp, ref GolangHuffmanTree h, int delta)
         {
             Block8x8* b = this.pointers.Block;
 
@@ -560,7 +559,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 
                 if (bit)
                 {
-                    int stuff = (int)Block8x8.GetScalarAt(b, 0);
+                    int stuff = Block8x8.GetScalarAt(b, 0);
 
                     // int stuff = (int)b[0];
                     stuff |= delta;

src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/InputProcessor.cs

@@ -8,7 +8,7 @@ using System.Runtime.CompilerServices;
 namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 {
     /// <summary>
-    /// Encapsulates stream reading and processing data and operations for <see cref="OrigJpegDecoderCore"/>.
+    /// Encapsulates stream reading and processing data and operations for <see cref="GolangJpegDecoderCore"/>.
     /// It's a value type for imporved data locality, and reduced number of CALLVIRT-s
     /// </summary>
     internal struct InputProcessor : IDisposable
@@ -27,14 +27,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// Initializes a new instance of the <see cref="InputProcessor"/> struct.
         /// </summary>
         /// <param name="inputStream">The input <see cref="Stream"/></param>
-        /// <param name="temp">Temporal buffer, same as <see cref="OrigJpegDecoderCore.Temp"/></param>
+        /// <param name="temp">Temporal buffer, same as <see cref="GolangJpegDecoderCore.Temp"/></param>
         public InputProcessor(Stream inputStream, byte[] temp)
         {
-            this.Bits = default(Bits);
+            this.Bits = default;
             this.Bytes = Bytes.Create();
             this.InputStream = inputStream;
             this.Temp = temp;
-            this.LastErrorCode = OrigDecoderErrorCode.NoError;
+            this.LastErrorCode = GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
@@ -43,20 +43,20 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         public Stream InputStream { get; }
 
         /// <summary>
-        /// Gets the temporary buffer, same instance as <see cref="OrigJpegDecoderCore.Temp"/>
+        /// Gets the temporary buffer, same instance as <see cref="GolangJpegDecoderCore.Temp"/>
         /// </summary>
         public byte[] Temp { get; }
 
         /// <summary>
         /// Gets a value indicating whether an unexpected EOF reached in <see cref="InputStream"/>.
         /// </summary>
-        public bool ReachedEOF => this.LastErrorCode == OrigDecoderErrorCode.UnexpectedEndOfStream;
+        public bool ReachedEOF => this.LastErrorCode == GolangDecoderErrorCode.UnexpectedEndOfStream;
 
-        public bool HasError => this.LastErrorCode != OrigDecoderErrorCode.NoError;
+        public bool HasError => this.LastErrorCode != GolangDecoderErrorCode.NoError;
 
-        public OrigDecoderErrorCode LastErrorCode { get; private set; }
+        public GolangDecoderErrorCode LastErrorCode { get; private set; }
 
-        public void ResetErrorState() => this.LastErrorCode = OrigDecoderErrorCode.NoError;
+        public void ResetErrorState() => this.LastErrorCode = GolangDecoderErrorCode.NoError;
 
         /// <summary>
         /// If errorCode indicates unexpected EOF, sets <see cref="ReachedEOF"/> to true and returns false.
@@ -65,7 +65,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// <returns>A <see cref="bool"/> indicating whether EOF reached</returns>
         public bool CheckEOFEnsureNoError()
         {
-            if (this.LastErrorCode == OrigDecoderErrorCode.UnexpectedEndOfStream)
+            if (this.LastErrorCode == GolangDecoderErrorCode.UnexpectedEndOfStream)
             {
                 return false;
             }
@@ -81,7 +81,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// <returns>A <see cref="bool"/> indicating whether EOF reached</returns>
         public bool CheckEOF()
         {
-            if (this.LastErrorCode == OrigDecoderErrorCode.UnexpectedEndOfStream)
+            if (this.LastErrorCode == GolangDecoderErrorCode.UnexpectedEndOfStream)
             {
                 return false;
             }
@@ -106,7 +106,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public OrigDecoderErrorCode ReadByteUnsafe(out byte result)
+        public GolangDecoderErrorCode ReadByteUnsafe(out byte result)
         {
             this.LastErrorCode = this.Bytes.ReadByteUnsafe(this.InputStream, out result);
             return this.LastErrorCode;
@@ -117,13 +117,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// TODO: This method (and also the usages) could be optimized by batching!
         /// </summary>
         /// <param name="result">The decoded bit as a <see cref="bool"/></param>
-        /// <returns>The <see cref="OrigDecoderErrorCode" /></returns>
-        public OrigDecoderErrorCode DecodeBitUnsafe(out bool result)
+        /// <returns>The <see cref="GolangDecoderErrorCode" /></returns>
+        public GolangDecoderErrorCode DecodeBitUnsafe(out bool result)
         {
             if (this.Bits.UnreadBits == 0)
             {
                 this.LastErrorCode = this.Bits.Ensure1BitUnsafe(ref this);
-                if (this.LastErrorCode != OrigDecoderErrorCode.NoError)
+                if (this.LastErrorCode != GolangDecoderErrorCode.NoError)
                 {
                     result = false;
                     return this.LastErrorCode;
@@ -133,18 +133,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             result = (this.Bits.Accumulator & this.Bits.Mask) != 0;
             this.Bits.UnreadBits--;
             this.Bits.Mask >>= 1;
-            return this.LastErrorCode = OrigDecoderErrorCode.NoError;
+            return this.LastErrorCode = GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
         /// Reads exactly length bytes into data. It does not care about byte stuffing.
-        /// Does not throw on errors, returns <see cref="OrigJpegDecoderCore"/> instead!
+        /// Does not throw on errors, returns <see cref="GolangJpegDecoderCore"/> instead!
         /// </summary>
         /// <param name="data">The data to write to.</param>
         /// <param name="offset">The offset in the source buffer</param>
         /// <param name="length">The number of bytes to read</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode ReadFullUnsafe(byte[] data, int offset, int length)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode ReadFullUnsafe(byte[] data, int offset, int length)
         {
             // Unread the overshot bytes, if any.
             if (this.Bytes.UnreadableBytes != 0)
@@ -157,8 +157,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 this.Bytes.UnreadableBytes = 0;
             }
 
-            this.LastErrorCode = OrigDecoderErrorCode.NoError;
-            while (length > 0 && this.LastErrorCode == OrigDecoderErrorCode.NoError)
+            this.LastErrorCode = GolangDecoderErrorCode.NoError;
+            while (length > 0 && this.LastErrorCode == GolangDecoderErrorCode.NoError)
             {
                 if (this.Bytes.J - this.Bytes.I >= length)
                 {
@@ -185,13 +185,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="count">The number of bits to decode.</param>
         /// <param name="result">The <see cref="uint" /> result</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode DecodeBitsUnsafe(int count, out int result)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode DecodeBitsUnsafe(int count, out int result)
         {
             if (this.Bits.UnreadBits < count)
             {
                 this.LastErrorCode = this.Bits.EnsureNBitsUnsafe(count, ref this);
-                if (this.LastErrorCode != OrigDecoderErrorCode.NoError)
+                if (this.LastErrorCode != GolangDecoderErrorCode.NoError)
                 {
                     result = 0;
                     return this.LastErrorCode;
@@ -202,7 +202,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             result = result & ((1 << count) - 1);
             this.Bits.UnreadBits -= count;
             this.Bits.Mask >>= count;
-            return this.LastErrorCode = OrigDecoderErrorCode.NoError;
+            return this.LastErrorCode = GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
@@ -210,8 +210,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="huffmanTree">The huffman value</param>
         /// <param name="result">The decoded <see cref="byte" /></param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode DecodeHuffmanUnsafe(ref OrigHuffmanTree huffmanTree, out int result)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode DecodeHuffmanUnsafe(ref GolangHuffmanTree huffmanTree, out int result)
         {
             result = 0;
 
@@ -224,9 +224,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             {
                 this.LastErrorCode = this.Bits.Ensure8BitsUnsafe(ref this);
 
-                if (this.LastErrorCode == OrigDecoderErrorCode.NoError)
+                if (this.LastErrorCode == GolangDecoderErrorCode.NoError)
                 {
-                    int lutIndex = (this.Bits.Accumulator >> (this.Bits.UnreadBits - OrigHuffmanTree.LutSizeLog2)) & 0xFF;
+                    int lutIndex = (this.Bits.Accumulator >> (this.Bits.UnreadBits - GolangHuffmanTree.LutSizeLog2)) & 0xFF;
                     int v = huffmanTree.Lut[lutIndex];
 
                     if (v != 0)
@@ -246,7 +246,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             }
 
             int code = 0;
-            for (int i = 0; i < OrigHuffmanTree.MaxCodeLength; i++)
+            for (int i = 0; i < GolangHuffmanTree.MaxCodeLength; i++)
             {
                 if (this.Bits.UnreadBits == 0)
                 {
@@ -269,7 +269,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 if (code <= huffmanTree.MaxCodes[i])
                 {
                     result = huffmanTree.GetValue(code, i);
-                    return this.LastErrorCode = OrigDecoderErrorCode.NoError;
+                    return this.LastErrorCode = GolangDecoderErrorCode.NoError;
                 }
 
                 code <<= 1;
@@ -279,7 +279,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             DecoderThrowHelper.ThrowImageFormatException.BadHuffmanCode();
 
             // DUMMY RETURN! C# doesn't know we have thrown an exception!
-            return OrigDecoderErrorCode.NoError;
+            return GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
@@ -295,11 +295,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
 
         /// <summary>
         /// Skips the next n bytes.
-        /// Does not throw, returns <see cref="OrigDecoderErrorCode"/> instead!
+        /// Does not throw, returns <see cref="GolangDecoderErrorCode"/> instead!
         /// </summary>
         /// <param name="count">The number of bytes to ignore.</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode SkipUnsafe(int count)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode SkipUnsafe(int count)
         {
             // Unread the overshot bytes, if any.
             if (this.Bytes.UnreadableBytes != 0)
@@ -328,13 +328,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
                 }
 
                 this.LastErrorCode = this.Bytes.FillUnsafe(this.InputStream);
-                if (this.LastErrorCode != OrigDecoderErrorCode.NoError)
+                if (this.LastErrorCode != GolangDecoderErrorCode.NoError)
                 {
                     return this.LastErrorCode;
                 }
             }
 
-            return this.LastErrorCode = OrigDecoderErrorCode.NoError;
+            return this.LastErrorCode = GolangDecoderErrorCode.NoError;
         }
 
         /// <summary>
@@ -374,8 +374,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         /// <param name="t">Byte</param>
         /// <param name="x">Read bits value</param>
-        /// <returns>The <see cref="OrigDecoderErrorCode"/></returns>
-        public OrigDecoderErrorCode ReceiveExtendUnsafe(int t, out int x)
+        /// <returns>The <see cref="GolangDecoderErrorCode"/></returns>
+        public GolangDecoderErrorCode ReceiveExtendUnsafe(int t, out int x)
         {
             this.LastErrorCode = this.Bits.ReceiveExtendUnsafe(t, ref this, out x);
             return this.LastErrorCode;
@@ -386,7 +386,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
         /// </summary>
         public void ResetHuffmanDecoder()
         {
-            this.Bits = default(Bits);
+            this.Bits = default;
         }
     }
 }

src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegDecoder.cs → src/ImageSharp/Formats/Jpeg/GolangPort/GolangJpegDecoder.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
     /// <summary>
     /// Image decoder for generating an image out of a jpg stream.
     /// </summary>
-    internal sealed class OrigJpegDecoder : IImageDecoder, IJpegDecoderOptions, IImageInfoDetector
+    internal sealed class GolangJpegDecoder : IImageDecoder, IJpegDecoderOptions, IImageInfoDetector
     {
         /// <summary>
         /// Gets or sets a value indicating whether the metadata should be ignored when the image is being decoded.
@@ -22,7 +22,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             Guard.NotNull(stream, nameof(stream));
 
-            using (var decoder = new OrigJpegDecoderCore(configuration, this))
+            using (var decoder = new GolangJpegDecoderCore(configuration, this))
             {
                 return decoder.Decode<TPixel>(stream);
             }
@@ -33,7 +33,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             Guard.NotNull(stream, nameof(stream));
 
-            using (var decoder = new OrigJpegDecoderCore(configuration, this))
+            using (var decoder = new GolangJpegDecoderCore(configuration, this))
             {
                 return decoder.Identify(stream);
             }

src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegDecoderCore.cs → src/ImageSharp/Formats/Jpeg/GolangPort/GolangJpegDecoderCore.cs

@@ -3,8 +3,9 @@
 
 using System.Collections.Generic;
 using System.IO;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 using SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder;
 using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
@@ -19,7 +20,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
     /// <summary>
     /// Performs the jpeg decoding operation.
     /// </summary>
-    internal sealed unsafe class OrigJpegDecoderCore : IRawJpegData
+    internal sealed unsafe class GolangJpegDecoderCore : IRawJpegData
     {
         /// <summary>
         /// The maximum number of color components
@@ -40,8 +41,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 #pragma warning disable SA1401 // FieldsMustBePrivate
 
         /// <summary>
-        /// Encapsulates stream reading and processing data and operations for <see cref="OrigJpegDecoderCore"/>.
-        /// It's a value type for imporved data locality, and reduced number of CALLVIRT-s
+        /// Encapsulates stream reading and processing data and operations for <see cref="GolangJpegDecoderCore"/>.
+        /// It's a value type for improved data locality, and reduced number of CALLVIRT-s
         /// </summary>
         public InputProcessor InputProcessor;
 #pragma warning restore SA401
@@ -79,16 +80,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         private AdobeMarker adobe;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="OrigJpegDecoderCore" /> class.
+        /// Initializes a new instance of the <see cref="GolangJpegDecoderCore" /> class.
         /// </summary>
         /// <param name="configuration">The configuration.</param>
         /// <param name="options">The options.</param>
-        public OrigJpegDecoderCore(Configuration configuration, IJpegDecoderOptions options)
+        public GolangJpegDecoderCore(Configuration configuration, IJpegDecoderOptions options)
         {
             this.IgnoreMetadata = options.IgnoreMetadata;
             this.configuration = configuration ?? Configuration.Default;
-            this.HuffmanTrees = OrigHuffmanTree.CreateHuffmanTrees();
-            this.QuantizationTables = new Block8x8F[MaxTq + 1];
             this.Temp = new byte[2 * Block8x8F.Size];
         }
 
@@ -98,15 +97,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         /// <summary>
         /// Gets the component array
         /// </summary>
-        public OrigComponent[] Components { get; private set; }
+        public GolangComponent[] Components { get; private set; }
 
         /// <summary>
         /// Gets the huffman trees
         /// </summary>
-        public OrigHuffmanTree[] HuffmanTrees { get; }
+        public GolangHuffmanTree[] HuffmanTrees { get; private set; }
 
         /// <inheritdoc />
-        public Block8x8F[] QuantizationTables { get; }
+        public Block8x8F[] QuantizationTables { get; private set; }
 
         /// <summary>
         /// Gets the temporary buffer used to store bytes read from the stream.
@@ -168,7 +167,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         public int MCUCountY => this.ImageSizeInMCU.Height;
 
         /// <summary>
-        /// Gets the the total number of MCU-s (Minimum Coded Units) in the image.
+        /// Gets the total number of MCU-s (Minimum Coded Units) in the image.
         /// </summary>
         public int TotalMCUCount => this.MCUCountX * this.MCUCountY;
 
@@ -193,7 +192,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             where TPixel : struct, IPixel<TPixel>
         {
             this.ParseStream(stream);
-
             return this.PostProcessIntoImage<TPixel>();
         }
 
@@ -204,7 +202,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         public IImageInfo Identify(Stream stream)
         {
             this.ParseStream(stream, true);
-
             return new ImageInfo(new PixelTypeInfo(this.BitsPerPixel), this.ImageWidth, this.ImageHeight, this.MetaData);
         }
 
@@ -213,9 +210,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             if (this.Components != null)
             {
-                foreach (OrigComponent component in this.Components)
+                foreach (GolangComponent component in this.Components)
                 {
-                    component.Dispose();
+                    component?.Dispose();
                 }
             }
 
@@ -223,7 +220,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         }
 
         /// <summary>
-        /// Read metadata from stream and read the blocks in the scans into <see cref="OrigComponent.SpectralBlocks"/>.
+        /// Read metadata from stream and read the blocks in the scans into <see cref="GolangComponent.SpectralBlocks"/>.
         /// </summary>
         /// <param name="stream">The stream</param>
         /// <param name="metadataOnly">Whether to decode metadata only.</param>
@@ -233,10 +230,16 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             this.InputStream = stream;
             this.InputProcessor = new InputProcessor(stream, this.Temp);
 
+            if (!metadataOnly)
+            {
+                this.HuffmanTrees = GolangHuffmanTree.CreateHuffmanTrees();
+                this.QuantizationTables = new Block8x8F[MaxTq + 1];
+            }
+
             // Check for the Start Of Image marker.
             this.InputProcessor.ReadFull(this.Temp, 0, 2);
 
-            if (this.Temp[0] != OrigJpegConstants.Markers.XFF || this.Temp[1] != OrigJpegConstants.Markers.SOI)
+            if (this.Temp[0] != JpegConstants.Markers.XFF || this.Temp[1] != JpegConstants.Markers.SOI)
             {
                 throw new ImageFormatException("Missing SOI marker.");
             }
@@ -300,12 +303,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                 }
 
                 // End Of Image.
-                if (marker == OrigJpegConstants.Markers.EOI)
+                if (marker == JpegConstants.Markers.EOI)
                 {
                     break;
                 }
 
-                if (marker >= OrigJpegConstants.Markers.RST0 && marker <= OrigJpegConstants.Markers.RST7)
+                if (marker >= JpegConstants.Markers.RST0 && marker <= JpegConstants.Markers.RST7)
                 {
                     // Figures B.2 and B.16 of the specification suggest that restart markers should
                     // only occur between Entropy Coded Segments and not after the final ECS.
@@ -327,18 +330,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 
                 switch (marker)
                 {
-                    case OrigJpegConstants.Markers.SOF0:
-                    case OrigJpegConstants.Markers.SOF1:
-                    case OrigJpegConstants.Markers.SOF2:
-                        this.IsProgressive = marker == OrigJpegConstants.Markers.SOF2;
-                        this.ProcessStartOfFrameMarker(remaining);
-                        if (metadataOnly && this.isJFif)
-                        {
-                            return;
-                        }
+                    case JpegConstants.Markers.SOF0:
+                    case JpegConstants.Markers.SOF1:
+                    case JpegConstants.Markers.SOF2:
+                        this.IsProgressive = marker == JpegConstants.Markers.SOF2;
+                        this.ProcessStartOfFrameMarker(remaining, metadataOnly);
 
                         break;
-                    case OrigJpegConstants.Markers.DHT:
+                    case JpegConstants.Markers.DHT:
                         if (metadataOnly)
                         {
                             this.InputProcessor.Skip(remaining);
@@ -349,7 +348,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                         }
 
                         break;
-                    case OrigJpegConstants.Markers.DQT:
+                    case JpegConstants.Markers.DQT:
                         if (metadataOnly)
                         {
                             this.InputProcessor.Skip(remaining);
@@ -360,21 +359,26 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                         }
 
                         break;
-                    case OrigJpegConstants.Markers.SOS:
-                        if (metadataOnly)
+                    case JpegConstants.Markers.SOS:
+                        if (!metadataOnly)
                         {
-                            return;
+                            this.ProcessStartOfScanMarker(remaining);
+                            if (this.InputProcessor.ReachedEOF)
+                            {
+                                // If unexpected EOF reached. We can stop processing bytes as we now have the image data.
+                                processBytes = false;
+                            }
                         }
-
-                        this.ProcessStartOfScanMarker(remaining);
-                        if (this.InputProcessor.ReachedEOF)
+                        else
                         {
-                            // If unexpected EOF reached. We can stop processing bytes as we now have the image data.
+                            // It's highly unlikely that APPn related data will be found after the SOS marker
+                            // We should have gathered everything we need by now.
                             processBytes = false;
                         }
 
                         break;
-                    case OrigJpegConstants.Markers.DRI:
+
+                    case JpegConstants.Markers.DRI:
                         if (metadataOnly)
                         {
                             this.InputProcessor.Skip(remaining);
@@ -385,21 +389,21 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                         }
 
                         break;
-                    case OrigJpegConstants.Markers.APP0:
+                    case JpegConstants.Markers.APP0:
                         this.ProcessApplicationHeaderMarker(remaining);
                         break;
-                    case OrigJpegConstants.Markers.APP1:
+                    case JpegConstants.Markers.APP1:
                         this.ProcessApp1Marker(remaining);
                         break;
-                    case OrigJpegConstants.Markers.APP2:
+                    case JpegConstants.Markers.APP2:
                         this.ProcessApp2Marker(remaining);
                         break;
-                    case OrigJpegConstants.Markers.APP14:
+                    case JpegConstants.Markers.APP14:
                         this.ProcessApp14Marker(remaining);
                         break;
                     default:
-                        if ((marker >= OrigJpegConstants.Markers.APP0 && marker <= OrigJpegConstants.Markers.APP15)
-                            || marker == OrigJpegConstants.Markers.COM)
+                        if ((marker >= JpegConstants.Markers.APP0 && marker <= JpegConstants.Markers.APP15)
+                            || marker == JpegConstants.Markers.COM)
                         {
                             this.InputProcessor.Skip(remaining);
                         }
@@ -425,7 +429,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         /// </summary>
         private void InitDerivedMetaDataProperties()
         {
-            if (this.isExif)
+            if (this.isJFif)
+            {
+                this.MetaData.HorizontalResolution = this.jFif.XDensity;
+                this.MetaData.VerticalResolution = this.jFif.YDensity;
+            }
+            else if (this.isExif)
             {
                 double horizontalValue = this.MetaData.ExifProfile.TryGetValue(ExifTag.XResolution, out ExifValue horizonalTag)
                     ? ((Rational)horizonalTag.Value).ToDouble()
@@ -441,10 +450,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                     this.MetaData.VerticalResolution = verticalValue;
                 }
             }
-            else if (this.isJFif)
+
+            if (this.MetaData.IccProfile?.CheckIsValid() == false)
             {
-                this.MetaData.HorizontalResolution = this.jFif.XDensity;
-                this.MetaData.VerticalResolution = this.jFif.YDensity;
+                this.MetaData.IccProfile = null;
             }
         }
 
@@ -634,7 +643,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         /// Processes the Start of Frame marker.  Specified in section B.2.2.
         /// </summary>
         /// <param name="remaining">The remaining bytes in the segment block.</param>
-        private void ProcessStartOfFrameMarker(int remaining)
+        /// <param name="metadataOnly">Whether to decode metadata only.</param>
+        private void ProcessStartOfFrameMarker(int remaining, bool metadataOnly)
         {
             if (this.ComponentCount != 0)
             {
@@ -674,27 +684,30 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                 throw new ImageFormatException("SOF has wrong length");
             }
 
-            this.Components = new OrigComponent[this.ComponentCount];
-
-            for (int i = 0; i < this.ComponentCount; i++)
+            if (!metadataOnly)
             {
-                byte componentIdentifier = this.Temp[6 + (3 * i)];
-                var component = new OrigComponent(componentIdentifier, i);
-                component.InitializeCoreData(this);
-                this.Components[i] = component;
-            }
+                this.Components = new GolangComponent[this.ComponentCount];
 
-            int h0 = this.Components[0].HorizontalSamplingFactor;
-            int v0 = this.Components[0].VerticalSamplingFactor;
+                for (int i = 0; i < this.ComponentCount; i++)
+                {
+                    byte componentIdentifier = this.Temp[6 + (3 * i)];
+                    var component = new GolangComponent(componentIdentifier, i);
+                    component.InitializeCoreData(this);
+                    this.Components[i] = component;
+                }
 
-            this.ImageSizeInMCU = this.ImageSizeInPixels.DivideRoundUp(8 * h0, 8 * v0);
+                int h0 = this.Components[0].HorizontalSamplingFactor;
+                int v0 = this.Components[0].VerticalSamplingFactor;
 
-            foreach (OrigComponent component in this.Components)
-            {
-                component.InitializeDerivedData(this.configuration.MemoryManager, this);
-            }
+                this.ImageSizeInMCU = this.ImageSizeInPixels.DivideRoundUp(8 * h0, 8 * v0);
+
+                this.ColorSpace = this.DeduceJpegColorSpace();
 
-            this.ColorSpace = this.DeduceJpegColorSpace();
+                foreach (GolangComponent component in this.Components)
+                {
+                    component.InitializeDerivedData(this.configuration.MemoryManager, this);
+                }
+            }
         }
 
         /// <summary>
@@ -714,18 +727,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                 this.InputProcessor.ReadFull(this.Temp, 0, 17);
 
                 int tc = this.Temp[0] >> 4;
-                if (tc > OrigHuffmanTree.MaxTc)
+                if (tc > GolangHuffmanTree.MaxTc)
                 {
                     throw new ImageFormatException("Bad Tc value");
                 }
 
                 int th = this.Temp[0] & 0x0f;
-                if (th > OrigHuffmanTree.MaxTh)
+                if (th > GolangHuffmanTree.MaxTh)
                 {
                     throw new ImageFormatException("Bad Th value");
                 }
 
-                int huffTreeIndex = (tc * OrigHuffmanTree.ThRowSize) + th;
+                int huffTreeIndex = (tc * GolangHuffmanTree.ThRowSize) + th;
                 this.HuffmanTrees[huffTreeIndex].ProcessDefineHuffmanTablesMarkerLoop(
                     ref this.InputProcessor,
                     this.Temp,
@@ -759,9 +772,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         /// </exception>
         private void ProcessStartOfScanMarker(int remaining)
         {
-            var scan = default(OrigJpegScanDecoder);
-            OrigJpegScanDecoder.InitStreamReading(&scan, this, remaining);
-            this.InputProcessor.Bits = default(Bits);
+            var scan = default(GolangJpegScanDecoder);
+            GolangJpegScanDecoder.InitStreamReading(&scan, this, remaining);
+            this.InputProcessor.Bits = default;
             scan.DecodeBlocks(this);
         }
 
@@ -772,19 +785,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                 case 1:
                     return JpegColorSpace.Grayscale;
                 case 3:
-                    if (!this.isAdobe || this.adobe.ColorTransform == OrigJpegConstants.Adobe.ColorTransformYCbCr)
+                    if (!this.isAdobe || this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformYCbCr)
                     {
                         return JpegColorSpace.YCbCr;
                     }
 
-                    if (this.adobe.ColorTransform == OrigJpegConstants.Adobe.ColorTransformUnknown)
+                    if (this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformUnknown)
                     {
                         return JpegColorSpace.RGB;
                     }
 
                     break;
                 case 4:
-                    if (this.adobe.ColorTransform == OrigJpegConstants.Adobe.ColorTransformYcck)
+                    if (this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformYcck)
                     {
                         return JpegColorSpace.Ycck;
                     }

src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegConstants.cs

@@ -1,189 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System.Collections.Generic;
-
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
-{
-    /// <summary>
-    /// Defines jpeg constants defined in the specification.
-    /// </summary>
-    internal static class OrigJpegConstants
-    {
-        /// <summary>
-        /// The maximum allowable length in each dimension of a jpeg image.
-        /// </summary>
-        public const ushort MaxLength = 65535;
-
-        /// <summary>
-        /// The list of mimetypes that equate to a jpeg.
-        /// </summary>
-        public static readonly IEnumerable<string> MimeTypes = new[] { "image/jpeg", "image/pjpeg" };
-
-        /// <summary>
-        /// The list of file extensions that equate to a jpeg.
-        /// </summary>
-        public static readonly IEnumerable<string> FileExtensions = new[] { "jpg", "jpeg", "jfif" };
-
-        /// <summary>
-        /// Describes common Jpeg markers
-        /// </summary>
-        internal static class Markers
-        {
-            /// <summary>
-            /// Marker prefix. Next byte is a marker.
-            /// </summary>
-            public const byte XFF = 0xff;
-
-            /// <summary>
-            /// Same as <see cref="XFF"/> but of type <see cref="int"/>
-            /// </summary>
-            public const int XFFInt = XFF;
-
-            /// <summary>
-            /// Start of Image
-            /// </summary>
-            public const byte SOI = 0xd8;
-
-            /// <summary>
-            /// Start of Frame (baseline DCT)
-            /// <remarks>
-            /// Indicates that this is a baseline DCT-based JPEG, and specifies the width, height, number of components,
-            /// and component subsampling (e.g., 4:2:0).
-            /// </remarks>
-            /// </summary>
-            public const byte SOF0 = 0xc0;
-
-            /// <summary>
-            /// Start Of Frame (Extended Sequential DCT)
-            /// <remarks>
-            /// Indicates that this is a progressive DCT-based JPEG, and specifies the width, height, number of components,
-            /// and component subsampling (e.g., 4:2:0).
-            /// </remarks>
-            /// </summary>
-            public const byte SOF1 = 0xc1;
-
-            /// <summary>
-            /// Start Of Frame (progressive DCT)
-            /// <remarks>
-            /// Indicates that this is a progressive DCT-based JPEG, and specifies the width, height, number of components,
-            /// and component subsampling (e.g., 4:2:0).
-            /// </remarks>
-            /// </summary>
-            public const byte SOF2 = 0xc2;
-
-            /// <summary>
-            /// Define Huffman Table(s)
-            /// <remarks>
-            /// Specifies one or more Huffman tables.
-            /// </remarks>
-            /// </summary>
-            public const byte DHT = 0xc4;
-
-            /// <summary>
-            /// Define Quantization Table(s)
-            /// <remarks>
-            /// Specifies one or more quantization tables.
-            /// </remarks>
-            /// </summary>
-            public const byte DQT = 0xdb;
-
-            /// <summary>
-            /// Define Restart Interval
-            /// <remarks>
-            /// Specifies the interval between RSTn markers, in macroblocks. This marker is followed by two bytes
-            /// indicating the fixed size so it can be treated like any other variable size segment.
-            /// </remarks>
-            /// </summary>
-            public const byte DRI = 0xdd;
-
-            /// <summary>
-            /// Define First Restart
-            /// <remarks>
-            /// Inserted every r macroblocks, where r is the restart interval set by a DRI marker.
-            /// Not used if there was no DRI marker. The low three bits of the marker code cycle in value from 0 to 7.
-            /// </remarks>
-            /// </summary>
-            public const byte RST0 = 0xd0;
-
-            /// <summary>
-            /// Define Eigth Restart
-            /// <remarks>
-            /// Inserted every r macroblocks, where r is the restart interval set by a DRI marker.
-            /// Not used if there was no DRI marker. The low three bits of the marker code cycle in value from 0 to 7.
-            /// </remarks>
-            /// </summary>
-            public const byte RST7 = 0xd7;
-
-            /// <summary>
-            /// Start of Scan
-            /// <remarks>
-            /// Begins a top-to-bottom scan of the image. In baseline DCT JPEG images, there is generally a single scan.
-            /// Progressive DCT JPEG images usually contain multiple scans. This marker specifies which slice of data it
-            /// will contain, and is immediately followed by entropy-coded data.
-            /// </remarks>
-            /// </summary>
-            public const byte SOS = 0xda;
-
-            /// <summary>
-            /// Comment
-            /// <remarks>
-            /// Contains a text comment.
-            /// </remarks>
-            /// </summary>
-            public const byte COM = 0xfe;
-
-            /// <summary>
-            /// End of Image
-            /// </summary>
-            public const byte EOI = 0xd9;
-
-            /// <summary>
-            /// Application specific marker for marking the jpeg format.
-            /// <see href="http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html"/>
-            /// </summary>
-            public const byte APP0 = 0xe0;
-
-            /// <summary>
-            /// Application specific marker for marking where to store metadata.
-            /// </summary>
-            public const byte APP1 = 0xe1;
-
-            /// <summary>
-            /// Application specific marker for marking where to store ICC profile information.
-            /// </summary>
-            public const byte APP2 = 0xe2;
-
-            /// <summary>
-            /// Application specific marker used by Adobe for storing encoding information for DCT filters.
-            /// </summary>
-            public const byte APP14 = 0xee;
-
-            /// <summary>
-            /// Application specific marker used by GraphicConverter to store JPEG quality.
-            /// </summary>
-            public const byte APP15 = 0xef;
-        }
-
-        /// <summary>
-        /// Describes Adobe specific markers <see href="http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe"/>
-        /// </summary>
-        internal static class Adobe
-        {
-            /// <summary>
-            /// The color transform is unknown.(RGB or CMYK)
-            /// </summary>
-            public const int ColorTransformUnknown = 0;
-
-            /// <summary>
-            /// The color transform is YCbCr (luminance, red chroma, blue chroma)
-            /// </summary>
-            public const int ColorTransformYCbCr = 1;
-
-            /// <summary>
-            /// The color transform is YCCK (luminance, red chroma, blue chroma, keyline)
-            /// </summary>
-            public const int ColorTransformYcck = 2;
-        }
-    }
-}

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegConstants.cs → src/ImageSharp/Formats/Jpeg/JpegConstants.cs

@@ -1,119 +1,141 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-// ReSharper disable InconsistentNaming
-namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
+using System.Collections.Generic;
+
+namespace SixLabors.ImageSharp.Formats.Jpeg
 {
     /// <summary>
-    /// Contains jpeg constant values
+    /// Contains jpeg constant values defined in the specification.
     /// </summary>
-    internal static class PdfJsJpegConstants
+    internal static class JpegConstants
     {
+        /// <summary>
+        /// The maximum allowable length in each dimension of a jpeg image.
+        /// </summary>
+        public const ushort MaxLength = 65535;
+
+        /// <summary>
+        /// The list of mimetypes that equate to a jpeg.
+        /// </summary>
+        public static readonly IEnumerable<string> MimeTypes = new[] { "image/jpeg", "image/pjpeg" };
+
+        /// <summary>
+        /// The list of file extensions that equate to a jpeg.
+        /// </summary>
+        public static readonly IEnumerable<string> FileExtensions = new[] { "jpg", "jpeg", "jfif" };
+
         /// <summary>
         /// Contains marker specific constants
         /// </summary>
-        public static class Markers
+        // ReSharper disable InconsistentNaming
+        internal static class Markers
         {
             /// <summary>
             /// The prefix used for all markers.
             /// </summary>
-            public const byte Prefix = 0xFF;
+            public const byte XFF = 0xFF;
+
+            /// <summary>
+            /// Same as <see cref="XFF"/> but of type <see cref="int"/>
+            /// </summary>
+            public const int XFFInt = XFF;
 
             /// <summary>
             /// The Start of Image marker
             /// </summary>
-            public const ushort SOI = 0xFFD8;
+            public const byte SOI = 0xD8;
 
             /// <summary>
             /// The End of Image marker
             /// </summary>
-            public const ushort EOI = 0xFFD9;
+            public const byte EOI = 0xD9;
 
             /// <summary>
             /// Application specific marker for marking the jpeg format.
             /// <see href="http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html"/>
             /// </summary>
-            public const ushort APP0 = 0xFFE0;
+            public const byte APP0 = 0xE0;
 
             /// <summary>
             /// Application specific marker for marking where to store metadata.
             /// </summary>
-            public const ushort APP1 = 0xFFE1;
+            public const byte APP1 = 0xE1;
 
             /// <summary>
             /// Application specific marker for marking where to store ICC profile information.
             /// </summary>
-            public const ushort APP2 = 0xFFE2;
+            public const byte APP2 = 0xE2;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP3 = 0xFFE3;
+            public const byte APP3 = 0xE3;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP4 = 0xFFE4;
+            public const byte APP4 = 0xE4;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP5 = 0xFFE5;
+            public const byte APP5 = 0xE5;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP6 = 0xFFE6;
+            public const byte APP6 = 0xE6;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP7 = 0xFFE7;
+            public const byte APP7 = 0xE7;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP8 = 0xFFE8;
+            public const byte APP8 = 0xE8;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP9 = 0xFFE9;
+            public const byte APP9 = 0xE9;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP10 = 0xFFEA;
+            public const byte APP10 = 0xEA;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP11 = 0xFFEB;
+            public const byte APP11 = 0xEB;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP12 = 0xFFEC;
+            public const byte APP12 = 0xEC;
 
             /// <summary>
             /// Application specific marker.
             /// </summary>
-            public const ushort APP13 = 0xFFED;
+            public const byte APP13 = 0xED;
 
             /// <summary>
             /// Application specific marker used by Adobe for storing encoding information for DCT filters.
             /// </summary>
-            public const ushort APP14 = 0xFFEE;
+            public const byte APP14 = 0xEE;
 
             /// <summary>
             /// Application specific marker used by GraphicConverter to store JPEG quality.
             /// </summary>
-            public const ushort APP15 = 0xFFEF;
+            public const byte APP15 = 0xEF;
 
             /// <summary>
             /// The text comment marker
             /// </summary>
-            public const ushort COM = 0xFFFE;
+            public const byte COM = 0xFE;
 
             /// <summary>
             /// Define Quantization Table(s) marker
@@ -121,7 +143,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// Specifies one or more quantization tables.
             /// </remarks>
             /// </summary>
-            public const ushort DQT = 0xFFDB;
+            public const byte DQT = 0xDB;
 
             /// <summary>
             /// Start of Frame (baseline DCT)
@@ -130,7 +152,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// and component subsampling (e.g., 4:2:0).
             /// </remarks>
             /// </summary>
-            public const ushort SOF0 = 0xFFC0;
+            public const byte SOF0 = 0xC0;
 
             /// <summary>
             /// Start Of Frame (Extended Sequential DCT)
@@ -139,7 +161,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// and component subsampling (e.g., 4:2:0).
             /// </remarks>
             /// </summary>
-            public const ushort SOF1 = 0xFFC1;
+            public const byte SOF1 = 0xC1;
 
             /// <summary>
             /// Start Of Frame (progressive DCT)
@@ -148,7 +170,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// and component subsampling (e.g., 4:2:0).
             /// </remarks>
             /// </summary>
-            public const ushort SOF2 = 0xFFC2;
+            public const byte SOF2 = 0xC2;
 
             /// <summary>
             /// Define Huffman Table(s)
@@ -156,15 +178,16 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// Specifies one or more Huffman tables.
             /// </remarks>
             /// </summary>
-            public const ushort DHT = 0xFFC4;
+            public const byte DHT = 0xC4;
 
             /// <summary>
             /// Define Restart Interval
             /// <remarks>
-            /// Specifies the interval between RSTn markers, in macroblocks.This marker is followed by two bytes indicating the fixed size so it can be treated like any other variable size segment.
+            /// Specifies the interval between RSTn markers, in macroblocks.This marker is followed by two bytes indicating the fixed size so
+            /// it can be treated like any other variable size segment.
             /// </remarks>
             /// </summary>
-            public const ushort DRI = 0xFFDD;
+            public const byte DRI = 0xDD;
 
             /// <summary>
             /// Start of Scan
@@ -174,7 +197,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// will contain, and is immediately followed by entropy-coded data.
             /// </remarks>
             /// </summary>
-            public const ushort SOS = 0xFFDA;
+            public const byte SOS = 0xDA;
 
             /// <summary>
             /// Define First Restart
@@ -183,7 +206,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// Not used if there was no DRI marker. The low three bits of the marker code cycle in value from 0 to 7.
             /// </remarks>
             /// </summary>
-            public const ushort RST0 = 0xFFD0;
+            public const byte RST0 = 0xD0;
 
             /// <summary>
             /// Define Eigth Restart
@@ -192,28 +215,28 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             /// Not used if there was no DRI marker. The low three bits of the marker code cycle in value from 0 to 7.
             /// </remarks>
             /// </summary>
-            public const ushort RST7 = 0xFFD7;
+            public const byte RST7 = 0xD7;
+        }
 
+        /// <summary>
+        /// Contains Adobe specific constants
+        /// </summary>
+        internal static class Adobe
+        {
             /// <summary>
-            /// Contains Adobe specific markers
+            /// The color transform is unknown.(RGB or CMYK)
             /// </summary>
-            public static class Adobe
-            {
-                /// <summary>
-                /// The color transform is unknown.(RGB or CMYK)
-                /// </summary>
-                public const byte ColorTransformUnknown = 0;
+            public const byte ColorTransformUnknown = 0;
 
-                /// <summary>
-                /// The color transform is YCbCr (luminance, red chroma, blue chroma)
-                /// </summary>
-                public const byte ColorTransformYCbCr = 1;
+            /// <summary>
+            /// The color transform is YCbCr (luminance, red chroma, blue chroma)
+            /// </summary>
+            public const byte ColorTransformYCbCr = 1;
 
-                /// <summary>
-                /// The color transform is YCCK (luminance, red chroma, blue chroma, keyline)
-                /// </summary>
-                public const byte ColorTransformYcck = 2;
-            }
+            /// <summary>
+            /// The color transform is YCCK (luminance, red chroma, blue chroma, keyline)
+            /// </summary>
+            public const byte ColorTransformYcck = 2;
         }
     }
 }

src/ImageSharp/Formats/Jpeg/JpegDecoder.cs

@@ -3,7 +3,7 @@
 
 using System.IO;
 
-using SixLabors.ImageSharp.Formats.Jpeg.GolangPort;
+using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg
@@ -24,7 +24,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         {
             Guard.NotNull(stream, nameof(stream));
 
-            using (var decoder = new OrigJpegDecoderCore(configuration, this))
+            using (var decoder = new PdfJsJpegDecoderCore(configuration, this))
             {
                 return decoder.Decode<TPixel>(stream);
             }
@@ -35,7 +35,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         {
             Guard.NotNull(stream, "stream");
 
-            using (var decoder = new OrigJpegDecoderCore(configuration, this))
+            using (var decoder = new PdfJsJpegDecoderCore(configuration, this))
             {
                 return decoder.Identify(stream);
             }

src/ImageSharp/Formats/Jpeg/JpegEncoder.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System.IO;
-using SixLabors.ImageSharp.Formats.Jpeg.GolangPort;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg

src/ImageSharp/Formats/Jpeg/GolangPort/JpegEncoderCore.cs → src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs

@@ -1,19 +1,16 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Buffers;
 using System.IO;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components;
-using SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder;
-using SixLabors.ImageSharp.Memory;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
 using SixLabors.ImageSharp.MetaData.Profiles.Icc;
 using SixLabors.ImageSharp.PixelFormats;
-using Block8x8F = SixLabors.ImageSharp.Formats.Jpeg.Common.Block8x8F;
 
-namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
+namespace SixLabors.ImageSharp.Formats.Jpeg
 {
     /// <summary>
     /// Image encoder for writing an image to a stream as a jpeg.
@@ -58,7 +55,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         /// </summary>
         private static readonly byte[] SosHeaderYCbCr =
             {
-                OrigJpegConstants.Markers.XFF, OrigJpegConstants.Markers.SOS,
+                JpegConstants.Markers.XFF, JpegConstants.Markers.SOS,
 
                 // Marker
                 0x00, 0x0c,
@@ -104,11 +101,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                     }
             };
 
-        /// <summary>
-        /// Lookup tables for converting Rgb to YCbCr
-        /// </summary>
-        private static RgbToYCbCrTables rgbToYCbCrTables = RgbToYCbCrTables.Create();
-
         /// <summary>
         /// A scratch buffer to reduce allocations.
         /// </summary>
@@ -190,7 +182,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             Guard.NotNull(image, nameof(image));
             Guard.NotNull(stream, nameof(stream));
 
-            ushort max = OrigJpegConstants.MaxLength;
+            ushort max = JpegConstants.MaxLength;
             if (image.Width >= max || image.Height >= max)
             {
                 throw new ImageFormatException($"Image is too large to encode at {image.Width}x{image.Height}.");
@@ -234,8 +226,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             this.WriteStartOfScan(image);
 
             // Write the End Of Image marker.
-            this.buffer[0] = OrigJpegConstants.Markers.XFF;
-            this.buffer[1] = OrigJpegConstants.Markers.EOI;
+            this.buffer[0] = JpegConstants.Markers.XFF;
+            this.buffer[1] = JpegConstants.Markers.EOI;
             stream.Write(this.buffer, 0, 2);
             stream.Flush();
         }
@@ -382,18 +374,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             // TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
             // (Partially done with YCbCrForwardConverter<TPixel>)
-            Block8x8F temp1 = default(Block8x8F);
-            Block8x8F temp2 = default(Block8x8F);
+            Block8x8F temp1 = default;
+            Block8x8F temp2 = default;
 
             Block8x8F onStackLuminanceQuantTable = this.luminanceQuantTable;
             Block8x8F onStackChrominanceQuantTable = this.chrominanceQuantTable;
 
-            ZigZag unzig = ZigZag.CreateUnzigTable();
+            var unzig = ZigZag.CreateUnzigTable();
 
             // ReSharper disable once InconsistentNaming
             int prevDCY = 0, prevDCCb = 0, prevDCCr = 0;
 
-            YCbCrForwardConverter<TPixel> pixelConverter = YCbCrForwardConverter<TPixel>.Create();
+            var pixelConverter = YCbCrForwardConverter<TPixel>.Create();
 
             for (int y = 0; y < pixels.Height; y += 8)
             {
@@ -437,12 +429,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         private void WriteApplicationHeader(short horizontalResolution, short verticalResolution)
         {
             // Write the start of image marker. Markers are always prefixed with with 0xff.
-            this.buffer[0] = OrigJpegConstants.Markers.XFF;
-            this.buffer[1] = OrigJpegConstants.Markers.SOI;
+            this.buffer[0] = JpegConstants.Markers.XFF;
+            this.buffer[1] = JpegConstants.Markers.SOI;
 
             // Write the JFIF headers
-            this.buffer[2] = OrigJpegConstants.Markers.XFF;
-            this.buffer[3] = OrigJpegConstants.Markers.APP0; // Application Marker
+            this.buffer[2] = JpegConstants.Markers.XFF;
+            this.buffer[3] = JpegConstants.Markers.APP0; // Application Marker
             this.buffer[4] = 0x00;
             this.buffer[5] = 0x10;
             this.buffer[6] = 0x4a; // J
@@ -502,7 +494,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             this.EmitHuffRLE((HuffIndex)((2 * (int)index) + 0), 0, dc - prevDC);
 
             // Emit the AC components.
-            HuffIndex h = (HuffIndex)((2 * (int)index) + 1);
+            var h = (HuffIndex)((2 * (int)index) + 1);
             int runLength = 0;
 
             for (int zig = 1; zig < Block8x8F.Size; zig++)
@@ -556,7 +548,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                 markerlen += 1 + 16 + s.Values.Length;
             }
 
-            this.WriteMarkerHeader(OrigJpegConstants.Markers.DHT, markerlen);
+            this.WriteMarkerHeader(JpegConstants.Markers.DHT, markerlen);
             for (int i = 0; i < specs.Length; i++)
             {
                 HuffmanSpec spec = specs[i];
@@ -590,7 +582,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             // Marker + quantization table lengths
             int markerlen = 2 + (QuantizationTableCount * (1 + Block8x8F.Size));
-            this.WriteMarkerHeader(OrigJpegConstants.Markers.DQT, markerlen);
+            this.WriteMarkerHeader(JpegConstants.Markers.DQT, markerlen);
 
             // Loop through and collect the tables as one array.
             // This allows us to reduce the number of writes to the stream.
@@ -627,8 +619,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 
             int length = data.Length + 2;
 
-            this.buffer[0] = OrigJpegConstants.Markers.XFF;
-            this.buffer[1] = OrigJpegConstants.Markers.APP1; // Application Marker
+            this.buffer[0] = JpegConstants.Markers.XFF;
+            this.buffer[1] = JpegConstants.Markers.APP1; // Application Marker
             this.buffer[2] = (byte)((length >> 8) & 0xFF);
             this.buffer[3] = (byte)(length & 0xFF);
 
@@ -686,8 +678,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 
                 dataLength -= length;
 
-                this.buffer[0] = OrigJpegConstants.Markers.XFF;
-                this.buffer[1] = OrigJpegConstants.Markers.APP2; // Application Marker
+                this.buffer[0] = JpegConstants.Markers.XFF;
+                this.buffer[1] = JpegConstants.Markers.APP2; // Application Marker
                 int markerLength = length + 16;
                 this.buffer[2] = (byte)((markerLength >> 8) & 0xFF);
                 this.buffer[3] = (byte)(markerLength & 0xFF);
@@ -759,7 +751,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 
             // Length (high byte, low byte), 8 + components * 3.
             int markerlen = 8 + (3 * componentCount);
-            this.WriteMarkerHeader(OrigJpegConstants.Markers.SOF0, markerlen);
+            this.WriteMarkerHeader(JpegConstants.Markers.SOF0, markerlen);
             this.buffer[0] = 8; // Data Precision. 8 for now, 12 and 16 bit jpegs not supported
             this.buffer[1] = (byte)(height >> 8);
             this.buffer[2] = (byte)(height & 0xff); // (2 bytes, Hi-Lo), must be > 0 if DNL not supported
@@ -827,20 +819,20 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             where TPixel : struct, IPixel<TPixel>
         {
             // TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
-            Block8x8F b = default(Block8x8F);
+            Block8x8F b = default;
 
-            BlockQuad cb = default(BlockQuad);
-            BlockQuad cr = default(BlockQuad);
-            Block8x8F* cbPtr = (Block8x8F*)cb.Data;
-            Block8x8F* crPtr = (Block8x8F*)cr.Data;
+            BlockQuad cb = default;
+            BlockQuad cr = default;
+            var cbPtr = (Block8x8F*)cb.Data;
+            var crPtr = (Block8x8F*)cr.Data;
 
-            Block8x8F temp1 = default(Block8x8F);
-            Block8x8F temp2 = default(Block8x8F);
+            Block8x8F temp1 = default;
+            Block8x8F temp2 = default;
 
             Block8x8F onStackLuminanceQuantTable = this.luminanceQuantTable;
             Block8x8F onStackChrominanceQuantTable = this.chrominanceQuantTable;
 
-            ZigZag unzig = ZigZag.CreateUnzigTable();
+            var unzig = ZigZag.CreateUnzigTable();
 
             var pixelConverter = YCbCrForwardConverter<TPixel>.Create();
 
@@ -902,7 +894,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         private void WriteMarkerHeader(byte marker, int length)
         {
             // Markers are always prefixed with with 0xff.
-            this.buffer[0] = OrigJpegConstants.Markers.XFF;
+            this.buffer[0] = JpegConstants.Markers.XFF;
             this.buffer[1] = marker;
             this.buffer[2] = (byte)(length >> 8);
             this.buffer[3] = (byte)(length & 0xff);

src/ImageSharp/Formats/Jpeg/JpegFormat.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System.Collections.Generic;
-using SixLabors.ImageSharp.Formats.Jpeg.GolangPort;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg
 {
@@ -18,9 +17,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         public string DefaultMimeType => "image/jpeg";
 
         /// <inheritdoc/>
-        public IEnumerable<string> MimeTypes => OrigJpegConstants.MimeTypes;
+        public IEnumerable<string> MimeTypes => JpegConstants.MimeTypes;
 
         /// <inheritdoc/>
-        public IEnumerable<string> FileExtensions => OrigJpegConstants.FileExtensions;
+        public IEnumerable<string> FileExtensions => JpegConstants.FileExtensions;
     }
 }

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/DoubleBufferedStreamReader.cs

@@ -0,0 +1,238 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.IO;
+using System.Runtime.CompilerServices;
+
+using SixLabors.ImageSharp.Memory;
+
+// TODO: This could be useful elsewhere.
+namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
+{
+    /// <summary>
+    /// A stream reader that add a secondary level buffer in addition to native stream buffered reading
+    /// to reduce the overhead of small incremental reads.
+    /// </summary>
+    internal class DoubleBufferedStreamReader : IDisposable
+    {
+        /// <summary>
+        /// The length, in bytes, of the buffering chunk
+        /// </summary>
+        public const int ChunkLength = 4096;
+
+        private const int ChunkLengthMinusOne = ChunkLength - 1;
+
+        private readonly Stream stream;
+
+        private readonly IManagedByteBuffer managedBuffer;
+
+        private readonly byte[] bufferChunk;
+
+        private readonly int length;
+
+        private int bytesRead;
+
+        private int position;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DoubleBufferedStreamReader"/> class.
+        /// </summary>
+        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
+        /// <param name="stream">The input stream.</param>
+        public DoubleBufferedStreamReader(MemoryManager memoryManager, Stream stream)
+        {
+            this.stream = stream;
+            this.length = (int)stream.Length;
+            this.managedBuffer = memoryManager.AllocateCleanManagedByteBuffer(ChunkLength);
+            this.bufferChunk = this.managedBuffer.Array;
+        }
+
+        /// <summary>
+        /// Gets the length, in bytes, of the stream
+        /// </summary>
+        public long Length => this.length;
+
+        /// <summary>
+        /// Gets or sets the current position within the stream
+        /// </summary>
+        public long Position
+        {
+            get => this.position;
+
+            set
+            {
+                // Reset everything. It's easier than tracking.
+                this.position = (int)value;
+                this.stream.Seek(this.position, SeekOrigin.Begin);
+                this.bytesRead = ChunkLength;
+            }
+        }
+
+        /// <summary>
+        /// Reads a byte from the stream and advances the position within the stream by one
+        /// byte, or returns -1 if at the end of the stream.
+        /// </summary>
+        /// <returns>The unsigned byte cast to an <see cref="int"/>, or -1 if at the end of the stream.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public int ReadByte()
+        {
+            if (this.position >= this.length)
+            {
+                return -1;
+            }
+
+            if (this.position == 0 || this.bytesRead > ChunkLengthMinusOne)
+            {
+                return this.ReadByteSlow();
+            }
+
+            this.position++;
+            return this.bufferChunk[this.bytesRead++];
+        }
+
+        /// <summary>
+        /// Skips the number of bytes in the stream
+        /// </summary>
+        /// <param name="count">The number of bytes to skip</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Skip(int count)
+        {
+            this.Position += count;
+        }
+
+        /// <summary>
+        /// Reads a sequence of bytes from the current stream and advances the position within the stream
+        /// by the number of bytes read.
+        /// </summary>
+        /// <param name="buffer">
+        /// An array of bytes. When this method returns, the buffer contains the specified
+        /// byte array with the values between offset and (offset + count - 1) replaced by
+        /// the bytes read from the current source.
+        /// </param>
+        /// <param name="offset">
+        /// The zero-based byte offset in buffer at which to begin storing the data read
+        /// from the current stream.
+        /// </param>
+        /// <param name="count">The maximum number of bytes to be read from the current stream.</param>
+        /// <returns>
+        /// The total number of bytes read into the buffer. This can be less than the number
+        /// of bytes requested if that many bytes are not currently available, or zero (0)
+        /// if the end of the stream has been reached.
+        /// </returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public int Read(byte[] buffer, int offset, int count)
+        {
+            if (buffer.Length > ChunkLength)
+            {
+                return this.ReadToBufferSlow(buffer, offset, count);
+            }
+
+            if (this.position == 0 || count + this.bytesRead > ChunkLength)
+            {
+                return this.ReadToChunkSlow(buffer, offset, count);
+            }
+
+            int n = this.GetCount(count);
+            this.CopyBytes(buffer, offset, n);
+
+            this.position += n;
+            this.bytesRead += n;
+
+            return n;
+        }
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            this.managedBuffer?.Dispose();
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private int ReadByteSlow()
+        {
+            if (this.position != this.stream.Position)
+            {
+                this.stream.Seek(this.position, SeekOrigin.Begin);
+            }
+
+            this.stream.Read(this.bufferChunk, 0, ChunkLength);
+            this.bytesRead = 0;
+
+            this.position++;
+            return this.bufferChunk[this.bytesRead++];
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private int ReadToChunkSlow(byte[] buffer, int offset, int count)
+        {
+            // Refill our buffer then copy.
+            if (this.position != this.stream.Position)
+            {
+                this.stream.Seek(this.position, SeekOrigin.Begin);
+            }
+
+            this.stream.Read(this.bufferChunk, 0, ChunkLength);
+            this.bytesRead = 0;
+
+            int n = this.GetCount(count);
+            this.CopyBytes(buffer, offset, n);
+
+            this.position += n;
+            this.bytesRead += n;
+
+            return n;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private int ReadToBufferSlow(byte[] buffer, int offset, int count)
+        {
+            // Read to target but don't copy to our chunk.
+            if (this.position != this.stream.Position)
+            {
+                this.stream.Seek(this.position, SeekOrigin.Begin);
+            }
+
+            int n = this.stream.Read(buffer, offset, count);
+            this.Position += n;
+            return n;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private int GetCount(int count)
+        {
+            int n = this.length - this.position;
+            if (n > count)
+            {
+                n = count;
+            }
+
+            if (n < 0)
+            {
+                n = 0;
+            }
+
+            return n;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void CopyBytes(byte[] buffer, int offset, int count)
+        {
+            if (count < 9)
+            {
+                int byteCount = count;
+                int read = this.bytesRead;
+                byte[] chunk = this.bufferChunk;
+
+                while (--byteCount > -1)
+                {
+                    buffer[offset + byteCount] = chunk[read + byteCount];
+                }
+            }
+            else
+            {
+                Buffer.BlockCopy(this.bufferChunk, this.bytesRead, buffer, offset, count);
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFileMarker.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System.Runtime.CompilerServices;
+
 namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 {
     /// <summary>
@@ -13,7 +15,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         /// </summary>
         /// <param name="marker">The marker</param>
         /// <param name="position">The position within the stream</param>
-        public PdfJsFileMarker(ushort marker, long position)
+        public PdfJsFileMarker(byte marker, long position)
         {
             this.Marker = marker;
             this.Position = position;
@@ -26,7 +28,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         /// <param name="marker">The marker</param>
         /// <param name="position">The position within the stream</param>
         /// <param name="invalid">Whether the current marker is invalid</param>
-        public PdfJsFileMarker(ushort marker, long position, bool invalid)
+        public PdfJsFileMarker(byte marker, long position, bool invalid)
         {
             this.Marker = marker;
             this.Position = position;
@@ -36,17 +38,29 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         /// <summary>
         /// Gets a value indicating whether the current marker is invalid
         /// </summary>
-        public bool Invalid { get; }
+        public bool Invalid
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get;
+        }
 
         /// <summary>
         /// Gets the position of the marker within a stream
         /// </summary>
-        public ushort Marker { get; }
+        public byte Marker
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get;
+        }
 
         /// <summary>
         /// Gets the position of the marker within a stream
         /// </summary>
-        public long Position { get; }
+        public long Position
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get;
+        }
 
         /// <inheritdoc/>
         public override string ToString()

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFrameComponent.cs

@@ -4,8 +4,9 @@
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.Primitives;
 
@@ -36,9 +37,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         public byte Id { get; }
 
         /// <summary>
-        /// Gets or sets Pred TODO: What does pred stand for?
+        /// Gets or sets DC coefficient predictor
         /// </summary>
-        public int Pred { get; set; }
+        public int DcPredictor { get; set; }
 
         /// <summary>
         /// Gets the horizontal sampling factor.

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsScanDecoder.cs

@@ -5,10 +5,10 @@ using System;
 #if DEBUG
 using System.Diagnostics;
 #endif
-using System.IO;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 {
@@ -21,6 +21,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 
         private byte[] markerBuffer;
 
+        private int mcuToRead;
+
+        private int mcusPerLine;
+
+        private int mcu;
+
         private int bitsData;
 
         private int bitsCount;
@@ -60,7 +66,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         /// <param name="successive">The successive approximation bit low end</param>
         public void DecodeScan(
             PdfJsFrame frame,
-            Stream stream,
+            DoubleBufferedStreamReader stream,
             PdfJsHuffmanTables dcHuffmanTables,
             PdfJsHuffmanTables acHuffmanTables,
             PdfJsFrameComponent[] components,
@@ -82,9 +88,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             this.unexpectedMarkerReached = false;
 
             bool progressive = frame.Progressive;
-            int mcusPerLine = frame.McusPerLine;
+            this.mcusPerLine = frame.McusPerLine;
 
-            int mcu = 0;
+            this.mcu = 0;
             int mcuExpected;
             if (componentsLength == 1)
             {
@@ -92,51 +98,46 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             }
             else
             {
-                mcuExpected = mcusPerLine * frame.McusPerColumn;
+                mcuExpected = this.mcusPerLine * frame.McusPerColumn;
             }
 
-            PdfJsFileMarker fileMarker;
-            while (mcu < mcuExpected)
+            while (this.mcu < mcuExpected)
             {
                 // Reset interval stuff
-                int mcuToRead = resetInterval != 0 ? Math.Min(mcuExpected - mcu, resetInterval) : mcuExpected;
+                this.mcuToRead = resetInterval != 0 ? Math.Min(mcuExpected - this.mcu, resetInterval) : mcuExpected;
                 for (int i = 0; i < components.Length; i++)
                 {
                     PdfJsFrameComponent c = components[i];
-                    c.Pred = 0;
+                    c.DcPredictor = 0;
                 }
 
                 this.eobrun = 0;
 
                 if (!progressive)
                 {
-                    this.DecodeScanBaseline(dcHuffmanTables, acHuffmanTables, components, componentsLength, mcusPerLine, mcuToRead, ref mcu, stream);
+                    this.DecodeScanBaseline(dcHuffmanTables, acHuffmanTables, components, componentsLength, stream);
                 }
                 else
                 {
                     bool isAc = this.specStart != 0;
                     bool isFirst = successivePrev == 0;
                     PdfJsHuffmanTables huffmanTables = isAc ? acHuffmanTables : dcHuffmanTables;
-                    this.DecodeScanProgressive(huffmanTables, isAc, isFirst, components, componentsLength, mcusPerLine, mcuToRead, ref mcu, stream);
+                    this.DecodeScanProgressive(huffmanTables, isAc, isFirst, components, componentsLength, stream);
                 }
 
-                // Find marker
+                // Reset
+                // TODO: I do not understand why these values are reset? We should surely be tracking the bits across mcu's?
                 this.bitsCount = 0;
-                fileMarker = PdfJsJpegDecoderCore.FindNextFileMarker(this.markerBuffer, stream);
-
-                // Some bad images seem to pad Scan blocks with e.g. zero bytes, skip past
-                // those to attempt to find a valid marker (fixes issue4090.pdf) in original code.
-                if (fileMarker.Invalid)
-                {
-#if DEBUG
-                    Debug.WriteLine($"DecodeScan - Unexpected MCU data at {stream.Position}, next marker is: {fileMarker.Marker:X}");
-#endif
-                }
+                this.bitsData = 0;
+                this.unexpectedMarkerReached = false;
 
-                ushort marker = fileMarker.Marker;
+                // Some images include more scan blocks than expected, skip past those and
+                // attempt to find the next valid marker
+                PdfJsFileMarker fileMarker = PdfJsJpegDecoderCore.FindNextFileMarker(this.markerBuffer, stream);
+                byte marker = fileMarker.Marker;
 
                 // RSTn - We've already read the bytes and altered the position so no need to skip
-                if (marker >= PdfJsJpegConstants.Markers.RST0 && marker <= PdfJsJpegConstants.Markers.RST7)
+                if (marker >= JpegConstants.Markers.RST0 && marker <= JpegConstants.Markers.RST7)
                 {
                     continue;
                 }
@@ -148,24 +149,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                     stream.Position = fileMarker.Position;
                     break;
                 }
-            }
-
-            fileMarker = PdfJsJpegDecoderCore.FindNextFileMarker(this.markerBuffer, stream);
 
-            // Some images include more Scan blocks than expected, skip past those and
-            // attempt to find the next valid marker (fixes issue8182.pdf) ref original code.
-            if (fileMarker.Invalid)
-            {
 #if DEBUG
                 Debug.WriteLine($"DecodeScan - Unexpected MCU data at {stream.Position}, next marker is: {fileMarker.Marker:X}");
 #endif
             }
-            else
-            {
-                // We've found a valid marker.
-                // Rewind the stream to the position of the marker
-                stream.Position = fileMarker.Position;
-            }
         }
 
         private void DecodeScanBaseline(
@@ -173,10 +161,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             PdfJsHuffmanTables acHuffmanTables,
             PdfJsFrameComponent[] components,
             int componentsLength,
-            int mcusPerLine,
-            int mcuToRead,
-            ref int mcu,
-            Stream stream)
+            DoubleBufferedStreamReader stream)
         {
             if (componentsLength == 1)
             {
@@ -185,20 +170,20 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 ref PdfJsHuffmanTable dcHuffmanTable = ref dcHuffmanTables[component.DCHuffmanTableId];
                 ref PdfJsHuffmanTable acHuffmanTable = ref acHuffmanTables[component.ACHuffmanTableId];
 
-                for (int n = 0; n < mcuToRead; n++)
+                for (int n = 0; n < this.mcuToRead; n++)
                 {
                     if (this.endOfStreamReached || this.unexpectedMarkerReached)
                     {
                         continue;
                     }
 
-                    this.DecodeBlockBaseline(ref dcHuffmanTable, ref acHuffmanTable, component, ref blockDataRef, mcu, stream);
-                    mcu++;
+                    this.DecodeBlockBaseline(ref dcHuffmanTable, ref acHuffmanTable, component, ref blockDataRef, stream);
+                    this.mcu++;
                 }
             }
             else
             {
-                for (int n = 0; n < mcuToRead; n++)
+                for (int n = 0; n < this.mcuToRead; n++)
                 {
                     for (int i = 0; i < componentsLength; i++)
                     {
@@ -218,12 +203,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                                     continue;
                                 }
 
-                                this.DecodeMcuBaseline(ref dcHuffmanTable, ref acHuffmanTable, component, ref blockDataRef, mcusPerLine, mcu, j, k, stream);
+                                this.DecodeMcuBaseline(ref dcHuffmanTable, ref acHuffmanTable, component, ref blockDataRef, j, k, stream);
                             }
                         }
                     }
 
-                    mcu++;
+                    this.mcu++;
                 }
             }
         }
@@ -234,10 +219,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             bool isFirst,
             PdfJsFrameComponent[] components,
             int componentsLength,
-            int mcusPerLine,
-            int mcuToRead,
-            ref int mcu,
-            Stream stream)
+            DoubleBufferedStreamReader stream)
         {
             if (componentsLength == 1)
             {
@@ -245,7 +227,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 ref short blockDataRef = ref MemoryMarshal.GetReference(MemoryMarshal.Cast<Block8x8, short>(component.SpectralBlocks.Span));
                 ref PdfJsHuffmanTable huffmanTable = ref huffmanTables[isAC ? component.ACHuffmanTableId : component.DCHuffmanTableId];
 
-                for (int n = 0; n < mcuToRead; n++)
+                for (int n = 0; n < this.mcuToRead; n++)
                 {
                     if (this.endOfStreamReached || this.unexpectedMarkerReached)
                     {
@@ -256,31 +238,31 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                     {
                         if (isFirst)
                         {
-                            this.DecodeBlockACFirst(ref huffmanTable, component, ref blockDataRef, mcu, stream);
+                            this.DecodeBlockACFirst(ref huffmanTable, component, ref blockDataRef, stream);
                         }
                         else
                         {
-                            this.DecodeBlockACSuccessive(ref huffmanTable, component, ref blockDataRef, mcu, stream);
+                            this.DecodeBlockACSuccessive(ref huffmanTable, component, ref blockDataRef, stream);
                         }
                     }
                     else
                     {
                         if (isFirst)
                         {
-                            this.DecodeBlockDCFirst(ref huffmanTable, component, ref blockDataRef, mcu, stream);
+                            this.DecodeBlockDCFirst(ref huffmanTable, component, ref blockDataRef, stream);
                         }
                         else
                         {
-                            this.DecodeBlockDCSuccessive(component, ref blockDataRef, mcu, stream);
+                            this.DecodeBlockDCSuccessive(component, ref blockDataRef, stream);
                         }
                     }
 
-                    mcu++;
+                    this.mcu++;
                 }
             }
             else
             {
-                for (int n = 0; n < mcuToRead; n++)
+                for (int n = 0; n < this.mcuToRead; n++)
                 {
                     for (int i = 0; i < componentsLength; i++)
                     {
@@ -294,56 +276,57 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                         {
                             for (int k = 0; k < h; k++)
                             {
+                                // No need to continue here.
                                 if (this.endOfStreamReached || this.unexpectedMarkerReached)
                                 {
-                                    continue;
+                                    break;
                                 }
 
                                 if (isAC)
                                 {
                                     if (isFirst)
                                     {
-                                        this.DecodeMcuACFirst(ref huffmanTable, component, ref blockDataRef, mcusPerLine, mcu, j, k, stream);
+                                        this.DecodeMcuACFirst(ref huffmanTable, component, ref blockDataRef, j, k, stream);
                                     }
                                     else
                                     {
-                                        this.DecodeMcuACSuccessive(ref huffmanTable, component, ref blockDataRef, mcusPerLine, mcu, j, k, stream);
+                                        this.DecodeMcuACSuccessive(ref huffmanTable, component, ref blockDataRef, j, k, stream);
                                     }
                                 }
                                 else
                                 {
                                     if (isFirst)
                                     {
-                                        this.DecodeMcuDCFirst(ref huffmanTable, component, ref blockDataRef, mcusPerLine, mcu, j, k, stream);
+                                        this.DecodeMcuDCFirst(ref huffmanTable, component, ref blockDataRef, j, k, stream);
                                     }
                                     else
                                     {
-                                        this.DecodeMcuDCSuccessive(component, ref blockDataRef, mcusPerLine, mcu, j, k, stream);
+                                        this.DecodeMcuDCSuccessive(component, ref blockDataRef, j, k, stream);
                                     }
                                 }
                             }
                         }
                     }
 
-                    mcu++;
+                    this.mcu++;
                 }
             }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeBlockBaseline(ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcu, Stream stream)
+        private void DecodeBlockBaseline(ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, DoubleBufferedStreamReader stream)
         {
-            int blockRow = mcu / component.WidthInBlocks;
-            int blockCol = mcu % component.WidthInBlocks;
+            int blockRow = this.mcu / component.WidthInBlocks;
+            int blockCol = this.mcu % component.WidthInBlocks;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
             this.DecodeBaseline(component, ref blockDataRef, offset, ref dcHuffmanTable, ref acHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeMcuBaseline(ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcusPerLine, int mcu, int row, int col, Stream stream)
+        private void DecodeMcuBaseline(ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int row, int col, DoubleBufferedStreamReader stream)
         {
-            int mcuRow = mcu / mcusPerLine;
-            int mcuCol = mcu % mcusPerLine;
+            int mcuRow = this.mcu / this.mcusPerLine;
+            int mcuCol = this.mcu % this.mcusPerLine;
             int blockRow = (mcuRow * component.VerticalSamplingFactor) + row;
             int blockCol = (mcuCol * component.HorizontalSamplingFactor) + col;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
@@ -351,19 +334,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeBlockDCFirst(ref PdfJsHuffmanTable dcHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcu, Stream stream)
+        private void DecodeBlockDCFirst(ref PdfJsHuffmanTable dcHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, DoubleBufferedStreamReader stream)
         {
-            int blockRow = mcu / component.WidthInBlocks;
-            int blockCol = mcu % component.WidthInBlocks;
+            int blockRow = this.mcu / component.WidthInBlocks;
+            int blockCol = this.mcu % component.WidthInBlocks;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
             this.DecodeDCFirst(component, ref blockDataRef, offset, ref dcHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeMcuDCFirst(ref PdfJsHuffmanTable dcHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcusPerLine, int mcu, int row, int col, Stream stream)
+        private void DecodeMcuDCFirst(ref PdfJsHuffmanTable dcHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int row, int col, DoubleBufferedStreamReader stream)
         {
-            int mcuRow = mcu / mcusPerLine;
-            int mcuCol = mcu % mcusPerLine;
+            int mcuRow = this.mcu / this.mcusPerLine;
+            int mcuCol = this.mcu % this.mcusPerLine;
             int blockRow = (mcuRow * component.VerticalSamplingFactor) + row;
             int blockCol = (mcuCol * component.HorizontalSamplingFactor) + col;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
@@ -371,19 +354,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeBlockDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int mcu, Stream stream)
+        private void DecodeBlockDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, DoubleBufferedStreamReader stream)
         {
-            int blockRow = mcu / component.WidthInBlocks;
-            int blockCol = mcu % component.WidthInBlocks;
+            int blockRow = this.mcu / component.WidthInBlocks;
+            int blockCol = this.mcu % component.WidthInBlocks;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
             this.DecodeDCSuccessive(component, ref blockDataRef, offset, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeMcuDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int mcusPerLine, int mcu, int row, int col, Stream stream)
+        private void DecodeMcuDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int row, int col, DoubleBufferedStreamReader stream)
         {
-            int mcuRow = mcu / mcusPerLine;
-            int mcuCol = mcu % mcusPerLine;
+            int mcuRow = this.mcu / this.mcusPerLine;
+            int mcuCol = this.mcu % this.mcusPerLine;
             int blockRow = (mcuRow * component.VerticalSamplingFactor) + row;
             int blockCol = (mcuCol * component.HorizontalSamplingFactor) + col;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
@@ -391,169 +374,257 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeBlockACFirst(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcu, Stream stream)
+        private void DecodeBlockACFirst(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, DoubleBufferedStreamReader stream)
         {
-            int blockRow = mcu / component.WidthInBlocks;
-            int blockCol = mcu % component.WidthInBlocks;
+            int blockRow = this.mcu / component.WidthInBlocks;
+            int blockCol = this.mcu % component.WidthInBlocks;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
-            this.DecodeACFirst(component, ref blockDataRef, offset, ref acHuffmanTable, stream);
+            this.DecodeACFirst(ref blockDataRef, offset, ref acHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeMcuACFirst(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcusPerLine, int mcu, int row, int col, Stream stream)
+        private void DecodeMcuACFirst(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int row, int col, DoubleBufferedStreamReader stream)
         {
-            int mcuRow = mcu / mcusPerLine;
-            int mcuCol = mcu % mcusPerLine;
+            int mcuRow = this.mcu / this.mcusPerLine;
+            int mcuCol = this.mcu % this.mcusPerLine;
             int blockRow = (mcuRow * component.VerticalSamplingFactor) + row;
             int blockCol = (mcuCol * component.HorizontalSamplingFactor) + col;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
-            this.DecodeACFirst(component, ref blockDataRef, offset, ref acHuffmanTable, stream);
+            this.DecodeACFirst(ref blockDataRef, offset, ref acHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeBlockACSuccessive(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcu, Stream stream)
+        private void DecodeBlockACSuccessive(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, DoubleBufferedStreamReader stream)
         {
-            int blockRow = mcu / component.WidthInBlocks;
-            int blockCol = mcu % component.WidthInBlocks;
+            int blockRow = this.mcu / component.WidthInBlocks;
+            int blockCol = this.mcu % component.WidthInBlocks;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
-            this.DecodeACSuccessive(component, ref blockDataRef, offset, ref acHuffmanTable, stream);
+            this.DecodeACSuccessive(ref blockDataRef, offset, ref acHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeMcuACSuccessive(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int mcusPerLine, int mcu, int row, int col, Stream stream)
+        private void DecodeMcuACSuccessive(ref PdfJsHuffmanTable acHuffmanTable, PdfJsFrameComponent component, ref short blockDataRef, int row, int col, DoubleBufferedStreamReader stream)
         {
-            int mcuRow = mcu / mcusPerLine;
-            int mcuCol = mcu % mcusPerLine;
+            int mcuRow = this.mcu / this.mcusPerLine;
+            int mcuCol = this.mcu % this.mcusPerLine;
             int blockRow = (mcuRow * component.VerticalSamplingFactor) + row;
             int blockCol = (mcuCol * component.HorizontalSamplingFactor) + col;
             int offset = component.GetBlockBufferOffset(blockRow, blockCol);
-            this.DecodeACSuccessive(component, ref blockDataRef, offset, ref acHuffmanTable, stream);
+            this.DecodeACSuccessive(ref blockDataRef, offset, ref acHuffmanTable, stream);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private int ReadBit(Stream stream)
+        private bool TryReadBit(DoubleBufferedStreamReader stream, out int bit)
         {
-            // TODO: I wonder if we can do this two bytes at a time; libjpeg turbo seems to do that?
-            if (this.bitsCount > 0)
+            if (this.bitsCount == 0)
             {
-                this.bitsCount--;
-                return (this.bitsData >> this.bitsCount) & 1;
+                if (!this.TryFillBits(stream))
+                {
+                    bit = 0;
+                    return false;
+                }
             }
 
-            this.bitsData = stream.ReadByte();
+            this.bitsCount--;
+            bit = (this.bitsData >> this.bitsCount) & 1;
+            return true;
+        }
 
-            if (this.bitsData == -0x1)
-            {
-                // We've encountered the end of the file stream which means there's no EOI marker ref the image
-                this.endOfStreamReached = true;
-            }
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private bool TryFillBits(DoubleBufferedStreamReader stream)
+        {
+            // TODO: Read more then 1 byte at a time.
+            // In LibJpegTurbo this is be 25 bits (32-7) but I cannot get this to work
+            // for some images, I'm assuming because I am crossing MCU boundaries and not maintining the correct buffer state.
+            const int MinGetBits = 7;
 
-            if (this.bitsData == PdfJsJpegConstants.Markers.Prefix)
+            if (!this.unexpectedMarkerReached)
             {
-                int nextByte = stream.ReadByte();
-                if (nextByte != 0)
+                // Attempt to load to the minimum bit count.
+                while (this.bitsCount < MinGetBits)
                 {
+                    int c = stream.ReadByte();
+
+                    switch (c)
+                    {
+                        case -0x1:
+
+                            // We've encountered the end of the file stream which means there's no EOI marker in the image.
+                            this.endOfStreamReached = true;
+                            return false;
+
+                        case JpegConstants.Markers.XFF:
+                            int nextByte = stream.ReadByte();
+
+                            if (nextByte == -0x1)
+                            {
+                                this.endOfStreamReached = true;
+                                return false;
+                            }
+
+                            if (nextByte != 0)
+                            {
 #if DEBUG
-                    Debug.WriteLine($"DecodeScan - Unexpected marker {(this.bitsData << 8) | nextByte:X} at {stream.Position}");
+                                Debug.WriteLine($"DecodeScan - Unexpected marker {(c << 8) | nextByte:X} at {stream.Position}");
 #endif
 
-                    // We've encountered an unexpected marker. Reverse the stream and exit.
-                    this.unexpectedMarkerReached = true;
-                    stream.Position -= 2;
-                }
+                                // We've encountered an unexpected marker. Reverse the stream and exit.
+                                this.unexpectedMarkerReached = true;
+                                stream.Position -= 2;
+
+                                // TODO: double check we need this.
+                                // Fill buffer with zero bits.
+                                if (this.bitsCount == 0)
+                                {
+                                    this.bitsData <<= MinGetBits;
+                                    this.bitsCount = MinGetBits;
+                                }
+
+                                return true;
+                            }
+
+                            break;
+                    }
 
-                // Unstuff 0
+                    // OK, load the next byte into bitsData
+                    this.bitsData = (this.bitsData << 8) | c;
+                    this.bitsCount += 8;
+                }
             }
 
-            this.bitsCount = 7;
+            return true;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private int PeekBits(int count)
+        {
+            return this.bitsData >> (this.bitsCount - count) & ((1 << count) - 1);
+        }
 
-            return this.bitsData >> 7;
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void DropBits(int count)
+        {
+            this.bitsCount -= count;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private short DecodeHuffman(ref PdfJsHuffmanTable tree, Stream stream)
+        private bool TryDecodeHuffman(ref PdfJsHuffmanTable tree, DoubleBufferedStreamReader stream, out short value)
         {
+            value = -1;
+
             // TODO: Implement fast Huffman decoding.
-            // NOTES # During investigation of the libjpeg implementation it appears that they pull 32bits at a time and operate on those bits
-            // using 3 methods: FillBits, PeekBits, and ReadBits. We should attempt to do the same.
-            short code = (short)this.ReadBit(stream);
-            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+            // In LibJpegTurbo a minimum of 25 bits (32-7) is collected from the stream
+            // Then a LUT is used to avoid the loop when decoding the Huffman value.
+            // using 3 methods: FillBits, PeekBits, and DropBits.
+            // The LUT has been ported from LibJpegTurbo as has this code but it doesn't work.
+            // this.TryFillBits(stream);
+            //
+            // const int LookAhead = 8;
+            // int look = this.PeekBits(LookAhead);
+            // look = tree.Lookahead[look];
+            // int bits = look >> LookAhead;
+            //
+            // if (bits <= LookAhead)
+            // {
+            //    this.DropBits(bits);
+            //    value = (short)(look & ((1 << LookAhead) - 1));
+            //    return true;
+            // }
+            if (!this.TryReadBit(stream, out int bit))
             {
-                return -1;
+                return false;
             }
 
+            short code = (short)bit;
+
             // "DECODE", section F.2.2.3, figure F.16, page 109 of T.81
             int i = 1;
 
             while (code > tree.MaxCode[i])
             {
-                code <<= 1;
-                code |= (short)this.ReadBit(stream);
-
-                if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                if (!this.TryReadBit(stream, out bit))
                 {
-                    return -1;
+                    return false;
                 }
 
+                code <<= 1;
+                code |= (short)bit;
                 i++;
             }
 
             int j = tree.ValOffset[i];
-            return tree.HuffVal[(j + code) & 0xFF];
+            value = tree.HuffVal[(j + code) & 0xFF];
+            return true;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private int Receive(int length, Stream stream)
+        private bool TryReceive(int length, DoubleBufferedStreamReader stream, out int value)
         {
-            int n = 0;
+            value = 0;
             while (length > 0)
             {
-                int bit = this.ReadBit(stream);
-                if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                if (!this.TryReadBit(stream, out int bit))
                 {
-                    return -1;
+                    return false;
                 }
 
-                n = (n << 1) | bit;
+                value = (value << 1) | bit;
                 length--;
             }
 
-            return n;
+            return true;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private int ReceiveAndExtend(int length, Stream stream)
+        private bool TryReceiveAndExtend(int length, DoubleBufferedStreamReader stream, out int value)
         {
             if (length == 1)
             {
-                return this.ReadBit(stream) == 1 ? 1 : -1;
-            }
+                if (!this.TryReadBit(stream, out value))
+                {
+                    return false;
+                }
 
-            int n = this.Receive(length, stream);
-            if (n >= 1 << (length - 1))
+                value = value == 1 ? 1 : -1;
+            }
+            else
             {
-                return n;
+                if (!this.TryReceive(length, stream, out value))
+                {
+                    return false;
+                }
+
+                if (value < 1 << (length - 1))
+                {
+                    value += (-1 << length) + 1;
+                }
             }
 
-            return n + (-1 << length) + 1;
+            return true;
         }
 
-        private void DecodeBaseline(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, Stream stream)
+        private void DecodeBaseline(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable dcHuffmanTable, ref PdfJsHuffmanTable acHuffmanTable, DoubleBufferedStreamReader stream)
         {
-            short t = this.DecodeHuffman(ref dcHuffmanTable, stream);
-            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+            if (!this.TryDecodeHuffman(ref dcHuffmanTable, stream, out short t))
             {
                 return;
             }
 
-            int diff = t == 0 ? 0 : this.ReceiveAndExtend(t, stream);
-            Unsafe.Add(ref blockDataRef, offset) = (short)(component.Pred += diff);
+            int diff = 0;
+            if (t != 0)
+            {
+                if (!this.TryReceiveAndExtend(t, stream, out diff))
+                {
+                    return;
+                }
+            }
+
+            Unsafe.Add(ref blockDataRef, offset) = (short)(component.DcPredictor += diff);
 
             int k = 1;
             while (k < 64)
             {
-                short rs = this.DecodeHuffman(ref acHuffmanTable, stream);
-                if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                if (!this.TryDecodeHuffman(ref acHuffmanTable, stream, out short rs))
                 {
                     return;
                 }
@@ -574,36 +645,42 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 
                 k += r;
 
-                if (k > 63)
+                byte z = this.dctZigZag[k];
+
+                if (!this.TryReceiveAndExtend(s, stream, out int re))
                 {
-                    break;
+                    return;
                 }
 
-                byte z = this.dctZigZag[k];
-                short re = (short)this.ReceiveAndExtend(s, stream);
-                Unsafe.Add(ref blockDataRef, offset + z) = re;
+                Unsafe.Add(ref blockDataRef, offset + z) = (short)re;
                 k++;
             }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeDCFirst(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable dcHuffmanTable, Stream stream)
+        private void DecodeDCFirst(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable dcHuffmanTable, DoubleBufferedStreamReader stream)
         {
-            short t = this.DecodeHuffman(ref dcHuffmanTable, stream);
-            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+            if (!this.TryDecodeHuffman(ref dcHuffmanTable, stream, out short t))
             {
                 return;
             }
 
-            int diff = t == 0 ? 0 : this.ReceiveAndExtend(t, stream) << this.successiveState;
-            Unsafe.Add(ref blockDataRef, offset) = (short)(component.Pred += diff);
+            int diff = 0;
+            if (t != 0)
+            {
+                if (!this.TryReceiveAndExtend(t, stream, out diff))
+                {
+                    return;
+                }
+            }
+
+            Unsafe.Add(ref blockDataRef, offset) = (short)(component.DcPredictor += diff << this.successiveState);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void DecodeDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int offset, Stream stream)
+        private void DecodeDCSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int offset, DoubleBufferedStreamReader stream)
         {
-            int bit = this.ReadBit(stream);
-            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+            if (!this.TryReadBit(stream, out int bit))
             {
                 return;
             }
@@ -611,7 +688,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             Unsafe.Add(ref blockDataRef, offset) |= (short)(bit << this.successiveState);
         }
 
-        private void DecodeACFirst(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable acHuffmanTable, Stream stream)
+        private void DecodeACFirst(ref short blockDataRef, int offset, ref PdfJsHuffmanTable acHuffmanTable, DoubleBufferedStreamReader stream)
         {
             if (this.eobrun > 0)
             {
@@ -623,8 +700,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
             int e = this.specEnd;
             while (k <= e)
             {
-                short rs = this.DecodeHuffman(ref acHuffmanTable, stream);
-                if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                if (!this.TryDecodeHuffman(ref acHuffmanTable, stream, out short rs))
                 {
                     return;
                 }
@@ -636,7 +712,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 {
                     if (r < 15)
                     {
-                        this.eobrun = this.Receive(r, stream) + (1 << r) - 1;
+                        if (!this.TryReceive(r, stream, out int eob))
+                        {
+                            return;
+                        }
+
+                        this.eobrun = eob + (1 << r) - 1;
                         break;
                     }
 
@@ -647,12 +728,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 k += r;
 
                 byte z = this.dctZigZag[k];
-                Unsafe.Add(ref blockDataRef, offset + z) = (short)(this.ReceiveAndExtend(s, stream) * (1 << this.successiveState));
+
+                if (!this.TryReceiveAndExtend(s, stream, out int v))
+                {
+                    return;
+                }
+
+                Unsafe.Add(ref blockDataRef, offset + z) = (short)(v * (1 << this.successiveState));
                 k++;
             }
         }
 
-        private void DecodeACSuccessive(PdfJsFrameComponent component, ref short blockDataRef, int offset, ref PdfJsHuffmanTable acHuffmanTable, Stream stream)
+        private void DecodeACSuccessive(ref short blockDataRef, int offset, ref PdfJsHuffmanTable acHuffmanTable, DoubleBufferedStreamReader stream)
         {
             int k = this.specStart;
             int e = this.specEnd;
@@ -667,8 +754,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 switch (this.successiveACState)
                 {
                     case 0: // Initial state
-                        short rs = this.DecodeHuffman(ref acHuffmanTable, stream);
-                        if (this.endOfStreamReached || this.unexpectedMarkerReached)
+
+                        if (!this.TryDecodeHuffman(ref acHuffmanTable, stream, out short rs))
                         {
                             return;
                         }
@@ -679,7 +766,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                         {
                             if (r < 15)
                             {
-                                this.eobrun = this.Receive(r, stream) + (1 << r);
+                                if (!this.TryReceive(r, stream, out int eob))
+                                {
+                                    return;
+                                }
+
+                                this.eobrun = eob + (1 << r);
                                 this.successiveACState = 4;
                             }
                             else
@@ -695,7 +787,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                                 throw new ImageFormatException("Invalid ACn encoding");
                             }
 
-                            this.successiveACNextValue = this.ReceiveAndExtend(s, stream);
+                            if (!this.TryReceiveAndExtend(s, stream, out int v))
+                            {
+                                return;
+                            }
+
+                            this.successiveACNextValue = v;
                             this.successiveACState = r > 0 ? 2 : 3;
                         }
 
@@ -704,8 +801,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                     case 2:
                         if (blockOffsetZRef != 0)
                         {
-                            int bit = this.ReadBit(stream);
-                            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                            if (!this.TryReadBit(stream, out int bit))
                             {
                                 return;
                             }
@@ -725,8 +821,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                     case 3: // Set value for a zero item
                         if (blockOffsetZRef != 0)
                         {
-                            int bit = this.ReadBit(stream);
-                            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                            if (!this.TryReadBit(stream, out int bit))
                             {
                                 return;
                             }
@@ -743,8 +838,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                     case 4: // Eob
                         if (blockOffsetZRef != 0)
                         {
-                            int bit = this.ReadBit(stream);
-                            if (this.endOfStreamReached || this.unexpectedMarkerReached)
+                            if (!this.TryReadBit(stream, out int bit))
                             {
                                 return;
                             }

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegDecoderCore.cs

@@ -7,8 +7,9 @@ using System.Collections.Generic;
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Formats.Jpeg.Common;
-using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
+
+using SixLabors.ImageSharp.Formats.Jpeg.Components;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.MetaData;
@@ -22,7 +23,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 {
     /// <summary>
     /// Performs the jpeg decoding operation.
-    /// Ported from <see href="https://github.com/mozilla/pdf.js/blob/master/src/core/jpg.js"/> with additional fixes to handle common encoding errors
+    /// Originally ported from <see href="https://github.com/mozilla/pdf.js/blob/master/src/core/jpg.js"/>
+    /// with additional fixes for both performance and common encoding errors.
     /// </summary>
     internal sealed class PdfJsJpegDecoderCore : IRawJpegData
     {
@@ -31,7 +33,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         public const int SupportedPrecision = 8;
 
-#pragma warning disable SA1401 // Fields should be private
         /// <summary>
         /// The global configuration
         /// </summary>
@@ -93,15 +94,23 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         public PdfJsFrame Frame { get; private set; }
 
+        /// <inheritdoc/>
+        public Size ImageSizeInPixels { get; private set; }
+
+        /// <summary>
+        /// Gets the number of MCU blocks in the image as <see cref="Size"/>.
+        /// </summary>
+        public Size ImageSizeInMCU { get; private set; }
+
         /// <summary>
         /// Gets the image width
         /// </summary>
-        public int ImageWidth { get; private set; }
+        public int ImageWidth => this.ImageSizeInPixels.Width;
 
         /// <summary>
         /// Gets the image height
         /// </summary>
-        public int ImageHeight { get; private set; }
+        public int ImageHeight => this.ImageSizeInPixels.Height;
 
         /// <summary>
         /// Gets the color depth, in number of bits per pixel.
@@ -111,7 +120,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// <summary>
         /// Gets the input stream.
         /// </summary>
-        public Stream InputStream { get; private set; }
+        public DoubleBufferedStreamReader InputStream { get; private set; }
 
         /// <summary>
         /// Gets a value indicating whether the metadata should be ignored when the image is being decoded.
@@ -123,17 +132,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         public ImageMetaData MetaData { get; private set; }
 
-        /// <inheritdoc/>
-        public Size ImageSizeInPixels => new Size(this.ImageWidth, this.ImageHeight);
-
         /// <inheritdoc/>
         public int ComponentCount { get; private set; }
 
         /// <inheritdoc/>
         public JpegColorSpace ColorSpace { get; private set; }
 
+        /// <summary>
+        /// Gets the components.
+        /// </summary>
+        public PdfJsFrameComponent[] Components => this.Frame.Components;
+
         /// <inheritdoc/>
-        public IEnumerable<IJpegComponent> Components => this.Frame.Components;
+        IEnumerable<IJpegComponent> IRawJpegData.Components => this.Components;
 
         /// <inheritdoc/>
         public Block8x8F[] QuantizationTables { get; private set; }
@@ -144,34 +155,35 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// <param name="marker">The buffer to read file markers to</param>
         /// <param name="stream">The input stream</param>
         /// <returns>The <see cref="PdfJsFileMarker"/></returns>
-        public static PdfJsFileMarker FindNextFileMarker(byte[] marker, Stream stream)
+        public static PdfJsFileMarker FindNextFileMarker(byte[] marker, DoubleBufferedStreamReader stream)
         {
             int value = stream.Read(marker, 0, 2);
 
             if (value == 0)
             {
-                return new PdfJsFileMarker(PdfJsJpegConstants.Markers.EOI, stream.Length - 2);
+                return new PdfJsFileMarker(JpegConstants.Markers.EOI, stream.Length - 2);
             }
 
-            if (marker[0] == PdfJsJpegConstants.Markers.Prefix)
+            if (marker[0] == JpegConstants.Markers.XFF)
             {
                 // According to Section B.1.1.2:
                 // "Any marker may optionally be preceded by any number of fill bytes, which are bytes assigned code 0xFF."
-                while (marker[1] == PdfJsJpegConstants.Markers.Prefix)
+                int m = marker[1];
+                while (m == JpegConstants.Markers.XFF)
                 {
                     int suffix = stream.ReadByte();
                     if (suffix == -1)
                     {
-                        return new PdfJsFileMarker(PdfJsJpegConstants.Markers.EOI, stream.Length - 2);
+                        return new PdfJsFileMarker(JpegConstants.Markers.EOI, stream.Length - 2);
                     }
 
-                    marker[1] = (byte)suffix;
+                    m = suffix;
                 }
 
-                return new PdfJsFileMarker(BinaryPrimitives.ReadUInt16BigEndian(marker), stream.Position - 2);
+                return new PdfJsFileMarker((byte)m, stream.Position - 2);
             }
 
-            return new PdfJsFileMarker(BinaryPrimitives.ReadUInt16BigEndian(marker), stream.Position - 2, true);
+            return new PdfJsFileMarker(marker[1], stream.Position - 2, true);
         }
 
         /// <summary>
@@ -184,6 +196,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             where TPixel : struct, IPixel<TPixel>
         {
             this.ParseStream(stream);
+            this.InitDerivedMetaDataProperties();
             return this.PostProcessIntoImage<TPixel>();
         }
 
@@ -194,7 +207,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         public IImageInfo Identify(Stream stream)
         {
             this.ParseStream(stream, true);
-            this.AssignResolution();
+            this.InitDerivedMetaDataProperties();
             return new ImageInfo(new PixelTypeInfo(this.BitsPerPixel), this.ImageWidth, this.ImageHeight, this.MetaData);
         }
 
@@ -206,136 +219,142 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         public void ParseStream(Stream stream, bool metadataOnly = false)
         {
             this.MetaData = new ImageMetaData();
-            this.InputStream = stream;
+            this.InputStream = new DoubleBufferedStreamReader(this.configuration.MemoryManager, stream);
 
             // Check for the Start Of Image marker.
-            var fileMarker = new PdfJsFileMarker(this.ReadUint16(), 0);
-            if (fileMarker.Marker != PdfJsJpegConstants.Markers.SOI)
+            this.InputStream.Read(this.markerBuffer, 0, 2);
+            var fileMarker = new PdfJsFileMarker(this.markerBuffer[1], 0);
+            if (fileMarker.Marker != JpegConstants.Markers.SOI)
             {
                 throw new ImageFormatException("Missing SOI marker.");
             }
 
-            ushort marker = this.ReadUint16();
+            this.InputStream.Read(this.markerBuffer, 0, 2);
+            byte marker = this.markerBuffer[1];
             fileMarker = new PdfJsFileMarker(marker, (int)this.InputStream.Position - 2);
 
-            this.QuantizationTables = new Block8x8F[4];
-
-            // this.quantizationTables = new PdfJsQuantizationTables(this.configuration.MemoryManager);
-            this.dcHuffmanTables = new PdfJsHuffmanTables();
-            this.acHuffmanTables = new PdfJsHuffmanTables();
-
-            while (fileMarker.Marker != PdfJsJpegConstants.Markers.EOI)
+            // Only assign what we need
+            if (!metadataOnly)
             {
-                // Get the marker length
-                int remaining = this.ReadUint16() - 2;
+                this.QuantizationTables = new Block8x8F[4];
+                this.dcHuffmanTables = new PdfJsHuffmanTables();
+                this.acHuffmanTables = new PdfJsHuffmanTables();
+            }
 
-                switch (fileMarker.Marker)
+            while (fileMarker.Marker != JpegConstants.Markers.EOI)
+            {
+                if (!fileMarker.Invalid)
                 {
-                    case PdfJsJpegConstants.Markers.APP0:
-                        this.ProcessApplicationHeaderMarker(remaining);
-                        break;
+                    // Get the marker length
+                    int remaining = this.ReadUint16() - 2;
 
-                    case PdfJsJpegConstants.Markers.APP1:
-                        this.ProcessApp1Marker(remaining);
-                        break;
-
-                    case PdfJsJpegConstants.Markers.APP2:
-                        this.ProcessApp2Marker(remaining);
-                        break;
-                    case PdfJsJpegConstants.Markers.APP3:
-                    case PdfJsJpegConstants.Markers.APP4:
-                    case PdfJsJpegConstants.Markers.APP5:
-                    case PdfJsJpegConstants.Markers.APP6:
-                    case PdfJsJpegConstants.Markers.APP7:
-                    case PdfJsJpegConstants.Markers.APP8:
-                    case PdfJsJpegConstants.Markers.APP9:
-                    case PdfJsJpegConstants.Markers.APP10:
-                    case PdfJsJpegConstants.Markers.APP11:
-                    case PdfJsJpegConstants.Markers.APP12:
-                    case PdfJsJpegConstants.Markers.APP13:
-                        this.InputStream.Skip(remaining);
-                        break;
+                    switch (fileMarker.Marker)
+                    {
+                        case JpegConstants.Markers.SOF0:
+                        case JpegConstants.Markers.SOF1:
+                        case JpegConstants.Markers.SOF2:
+                            this.ProcessStartOfFrameMarker(remaining, fileMarker, metadataOnly);
+                            break;
+
+                        case JpegConstants.Markers.SOS:
+                            if (!metadataOnly)
+                            {
+                                this.ProcessStartOfScanMarker();
+                                break;
+                            }
+                            else
+                            {
+                                // It's highly unlikely that APPn related data will be found after the SOS marker
+                                // We should have gathered everything we need by now.
+                                return;
+                            }
 
-                    case PdfJsJpegConstants.Markers.APP14:
-                        this.ProcessApp14Marker(remaining);
-                        break;
+                        case JpegConstants.Markers.DHT:
+                            if (metadataOnly)
+                            {
+                                this.InputStream.Skip(remaining);
+                            }
+                            else
+                            {
+                                this.ProcessDefineHuffmanTablesMarker(remaining);
+                            }
 
-                    case PdfJsJpegConstants.Markers.APP15:
-                    case PdfJsJpegConstants.Markers.COM:
-                        this.InputStream.Skip(remaining);
-                        break;
+                            break;
 
-                    case PdfJsJpegConstants.Markers.DQT:
-                        if (metadataOnly)
-                        {
-                            this.InputStream.Skip(remaining);
-                        }
-                        else
-                        {
-                            this.ProcessDefineQuantizationTablesMarker(remaining);
-                        }
+                        case JpegConstants.Markers.DQT:
+                            if (metadataOnly)
+                            {
+                                this.InputStream.Skip(remaining);
+                            }
+                            else
+                            {
+                                this.ProcessDefineQuantizationTablesMarker(remaining);
+                            }
 
-                        break;
+                            break;
 
-                    case PdfJsJpegConstants.Markers.SOF0:
-                    case PdfJsJpegConstants.Markers.SOF1:
-                    case PdfJsJpegConstants.Markers.SOF2:
-                        this.ProcessStartOfFrameMarker(remaining, fileMarker);
-                        if (metadataOnly && !this.jFif.Equals(default))
-                        {
-                            this.InputStream.Skip(remaining);
-                        }
-
-                        break;
+                        case JpegConstants.Markers.DRI:
+                            if (metadataOnly)
+                            {
+                                this.InputStream.Skip(remaining);
+                            }
+                            else
+                            {
+                                this.ProcessDefineRestartIntervalMarker(remaining);
+                            }
 
-                    case PdfJsJpegConstants.Markers.DHT:
-                        if (metadataOnly)
-                        {
+                            break;
+
+                        case JpegConstants.Markers.APP0:
+                            this.ProcessApplicationHeaderMarker(remaining);
+                            break;
+
+                        case JpegConstants.Markers.APP1:
+                            this.ProcessApp1Marker(remaining);
+                            break;
+
+                        case JpegConstants.Markers.APP2:
+                            this.ProcessApp2Marker(remaining);
+                            break;
+
+                        case JpegConstants.Markers.APP3:
+                        case JpegConstants.Markers.APP4:
+                        case JpegConstants.Markers.APP5:
+                        case JpegConstants.Markers.APP6:
+                        case JpegConstants.Markers.APP7:
+                        case JpegConstants.Markers.APP8:
+                        case JpegConstants.Markers.APP9:
+                        case JpegConstants.Markers.APP10:
+                        case JpegConstants.Markers.APP11:
+                        case JpegConstants.Markers.APP12:
+                        case JpegConstants.Markers.APP13:
                             this.InputStream.Skip(remaining);
-                        }
-                        else
-                        {
-                            this.ProcessDefineHuffmanTablesMarker(remaining);
-                        }
+                            break;
 
-                        break;
+                        case JpegConstants.Markers.APP14:
+                            this.ProcessApp14Marker(remaining);
+                            break;
 
-                    case PdfJsJpegConstants.Markers.DRI:
-                        if (metadataOnly)
-                        {
+                        case JpegConstants.Markers.APP15:
+                        case JpegConstants.Markers.COM:
                             this.InputStream.Skip(remaining);
-                        }
-                        else
-                        {
-                            this.ProcessDefineRestartIntervalMarker(remaining);
-                        }
-
-                        break;
-
-                    case PdfJsJpegConstants.Markers.SOS:
-                        if (!metadataOnly)
-                        {
-                            this.ProcessStartOfScanMarker();
-                        }
-
-                        break;
+                            break;
+                    }
                 }
 
                 // Read on.
                 fileMarker = FindNextFileMarker(this.markerBuffer, this.InputStream);
             }
-
-            this.ImageWidth = this.Frame.SamplesPerLine;
-            this.ImageHeight = this.Frame.Scanlines;
-            this.ComponentCount = this.Frame.ComponentCount;
         }
 
         /// <inheritdoc/>
         public void Dispose()
         {
+            this.InputStream?.Dispose();
             this.Frame?.Dispose();
 
             // Set large fields to null.
+            this.InputStream = null;
             this.Frame = null;
             this.dcHuffmanTables = null;
             this.acHuffmanTables = null;
@@ -354,11 +373,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             if (this.ComponentCount == 3)
             {
-                if (this.adobe.Equals(default) || this.adobe.ColorTransform == PdfJsJpegConstants.Markers.Adobe.ColorTransformYCbCr)
+                if (this.adobe.Equals(default) || this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformYCbCr)
                 {
                     return JpegColorSpace.YCbCr;
                 }
-                else if (this.adobe.ColorTransform == PdfJsJpegConstants.Markers.Adobe.ColorTransformUnknown)
+
+                if (this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformUnknown)
                 {
                     return JpegColorSpace.RGB;
                 }
@@ -366,7 +386,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             if (this.ComponentCount == 4)
             {
-                return this.adobe.ColorTransform == PdfJsJpegConstants.Markers.Adobe.ColorTransformYcck
+                return this.adobe.ColorTransform == JpegConstants.Adobe.ColorTransformYcck
                     ? JpegColorSpace.Ycck
                     : JpegColorSpace.Cmyk;
             }
@@ -375,11 +395,16 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         }
 
         /// <summary>
-        /// Assigns the horizontal and vertical resolution to the image if it has a JFIF header or EXIF metadata.
+        /// Assigns derived metadata properties to <see cref="MetaData"/>, eg. horizontal and vertical resolution if it has a JFIF header.
         /// </summary>
-        private void AssignResolution()
+        private void InitDerivedMetaDataProperties()
         {
-            if (this.isExif)
+            if (this.jFif.XDensity > 0 && this.jFif.YDensity > 0)
+            {
+                this.MetaData.HorizontalResolution = this.jFif.XDensity;
+                this.MetaData.VerticalResolution = this.jFif.YDensity;
+            }
+            else if (this.isExif)
             {
                 double horizontalValue = this.MetaData.ExifProfile.TryGetValue(ExifTag.XResolution, out ExifValue horizontalTag)
                     ? ((Rational)horizontalTag.Value).ToDouble()
@@ -395,10 +420,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                     this.MetaData.VerticalResolution = verticalValue;
                 }
             }
-            else if (this.jFif.XDensity > 0 && this.jFif.YDensity > 0)
+
+            if (this.MetaData.IccProfile?.CheckIsValid() == false)
             {
-                this.MetaData.HorizontalResolution = this.jFif.XDensity;
-                this.MetaData.VerticalResolution = this.jFif.YDensity;
+                this.MetaData.IccProfile = null;
             }
         }
 
@@ -593,7 +618,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         /// <param name="remaining">The remaining bytes in the segment block.</param>
         /// <param name="frameMarker">The current frame marker.</param>
-        private void ProcessStartOfFrameMarker(int remaining, PdfJsFileMarker frameMarker)
+        /// <param name="metadataOnly">Whether to parse metadata only</param>
+        private void ProcessStartOfFrameMarker(int remaining, PdfJsFileMarker frameMarker, bool metadataOnly)
         {
             if (this.Frame != null)
             {
@@ -610,49 +636,59 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 
             this.Frame = new PdfJsFrame
             {
-                Extended = frameMarker.Marker == PdfJsJpegConstants.Markers.SOF1,
-                Progressive = frameMarker.Marker == PdfJsJpegConstants.Markers.SOF2,
+                Extended = frameMarker.Marker == JpegConstants.Markers.SOF1,
+                Progressive = frameMarker.Marker == JpegConstants.Markers.SOF2,
                 Precision = this.temp[0],
                 Scanlines = (short)((this.temp[1] << 8) | this.temp[2]),
                 SamplesPerLine = (short)((this.temp[3] << 8) | this.temp[4]),
                 ComponentCount = this.temp[5]
             };
 
+            this.ImageSizeInPixels = new Size(this.Frame.SamplesPerLine, this.Frame.Scanlines);
+
             int maxH = 0;
             int maxV = 0;
             int index = 6;
 
-            // No need to pool this. They max out at 4
-            this.Frame.ComponentIds = new byte[this.Frame.ComponentCount];
-            this.Frame.Components = new PdfJsFrameComponent[this.Frame.ComponentCount];
+            this.ComponentCount = this.Frame.ComponentCount;
 
-            for (int i = 0; i < this.Frame.Components.Length; i++)
+            if (!metadataOnly)
             {
-                byte hv = this.temp[index + 1];
-                int h = hv >> 4;
-                int v = hv & 15;
+                // No need to pool this. They max out at 4
+                this.Frame.ComponentIds = new byte[this.Frame.ComponentCount];
+                this.Frame.Components = new PdfJsFrameComponent[this.Frame.ComponentCount];
+                this.ColorSpace = this.DeduceJpegColorSpace();
 
-                if (maxH < h)
+                for (int i = 0; i < this.Frame.ComponentCount; i++)
                 {
-                    maxH = h;
-                }
+                    byte hv = this.temp[index + 1];
+                    int h = hv >> 4;
+                    int v = hv & 15;
 
-                if (maxV < v)
-                {
-                    maxV = v;
-                }
+                    if (maxH < h)
+                    {
+                        maxH = h;
+                    }
 
-                var component = new PdfJsFrameComponent(this.configuration.MemoryManager, this.Frame, this.temp[index], h, v, this.temp[index + 2], i);
+                    if (maxV < v)
+                    {
+                        maxV = v;
+                    }
 
-                this.Frame.Components[i] = component;
-                this.Frame.ComponentIds[i] = component.Id;
+                    var component = new PdfJsFrameComponent(this.configuration.MemoryManager, this.Frame, this.temp[index], h, v, this.temp[index + 2], i);
 
-                index += 3;
-            }
+                    this.Frame.Components[i] = component;
+                    this.Frame.ComponentIds[i] = component.Id;
 
-            this.Frame.MaxHorizontalFactor = maxH;
-            this.Frame.MaxVerticalFactor = maxV;
-            this.Frame.InitComponents();
+                    index += 3;
+                }
+
+                this.Frame.MaxHorizontalFactor = maxH;
+                this.Frame.MaxVerticalFactor = maxV;
+                this.ColorSpace = this.DeduceJpegColorSpace();
+                this.Frame.InitComponents();
+                this.ImageSizeInMCU = new Size(this.Frame.McusPerLine, this.Frame.McusPerColumn);
+            }
         }
 
         /// <summary>
@@ -798,8 +834,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         private Image<TPixel> PostProcessIntoImage<TPixel>()
             where TPixel : struct, IPixel<TPixel>
         {
-            this.ColorSpace = this.DeduceJpegColorSpace();
-            this.AssignResolution();
             using (var postProcessor = new JpegImagePostProcessor(this.configuration.MemoryManager, this))
             {
                 var image = new Image<TPixel>(this.configuration, this.ImageWidth, this.ImageHeight, this.MetaData);

src/ImageSharp/Formats/Png/Filters/AverageFilter.cs

@@ -29,21 +29,19 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             ref byte prevBaseRef = ref MemoryMarshal.GetReference(previousScanline);
 
             // Average(x) + floor((Raw(x-bpp)+Prior(x))/2)
-            for (int x = 1; x < scanline.Length; x++)
+            int x = 1;
+            for (; x <= bytesPerPixel /* Note the <= because x starts at 1 */; ++x) {
+                ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                scan = (byte)(scan + (above >> 1));
+            }
+
+            for (; x < scanline.Length; ++x)
             {
-                if (x - bytesPerPixel < 1)
-                {
-                    ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    scan = (byte)((scan + (above >> 1)) % 256);
-                }
-                else
-                {
-                    ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
-                    byte left = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    scan = (byte)((scan + Average(left, above)) % 256);
-                }
+                ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
+                byte left = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                scan = (byte)(scan + Average(left, above));
             }
         }
 
@@ -69,25 +67,24 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             // Average(x) = Raw(x) - floor((Raw(x-bpp)+Prior(x))/2)
             resultBaseRef = 3;
 
-            for (int x = 0; x < scanline.Length; x++)
-            {
-                if (x - bytesPerPixel < 0)
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)((scan - (above >> 1)) % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
-                else
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    byte left = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)((scan - Average(left, above)) % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
+            int x = 0;
+            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - (above >> 1));
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
+            }
+
+            for (int xLeft = x - bytesPerPixel; x < scanline.Length; ++xLeft /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                byte left = Unsafe.Add(ref scanBaseRef, xLeft);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - Average(left, above));
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
             }
 
             sum -= 3;

src/ImageSharp/Formats/Png/Filters/NoneFilter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Png.Filters
 {
@@ -20,12 +19,12 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
         /// <param name="scanline">The scanline to encode</param>
         /// <param name="result">The filtered scanline result.</param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Encode(Span<byte> scanline, Span<byte> result)
+        public static void Encode(ReadOnlySpan<byte> scanline, Span<byte> result)
         {
             // Insert a byte before the data.
             result[0] = 0;
             result = result.Slice(1);
-            SpanHelper.Copy(scanline, result);
+            scanline.Slice(0, Math.Min(scanline.Length, result.Length)).CopyTo(result);
         }
     }
-}
+}

src/ImageSharp/Formats/Png/Filters/PaethFilter.cs

@@ -30,21 +30,22 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             ref byte prevBaseRef = ref MemoryMarshal.GetReference(previousScanline);
 
             // Paeth(x) + PaethPredictor(Raw(x-bpp), Prior(x), Prior(x-bpp))
-            int offset = bytesPerPixel + 1;
-            for (int x = 1; x < offset; x++)
+            int offset = bytesPerPixel + 1; // Add one bcause x starts at one.
+            int x = 1;
+            for (; x < offset; x++)
             {
                 ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
                 byte above = Unsafe.Add(ref prevBaseRef, x);
                 scan = (byte)(scan + above);
             }
 
-            for (int x = offset; x < scanline.Length; x++)
+            for (; x < scanline.Length; x++)
             {
                 ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
                 byte left = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
                 byte above = Unsafe.Add(ref prevBaseRef, x);
                 byte upperLeft = Unsafe.Add(ref prevBaseRef, x - bytesPerPixel);
-                scan = (byte)(scan + PaethPredicator(left, above, upperLeft));
+                scan = (byte)(scan + PaethPredictor(left, above, upperLeft));
             }
         }
 
@@ -70,26 +71,25 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             // Paeth(x) = Raw(x) - PaethPredictor(Raw(x-bpp), Prior(x), Prior(x - bpp))
             resultBaseRef = 4;
 
-            for (int x = 0; x < scanline.Length; x++)
-            {
-                if (x - bytesPerPixel < 0)
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)((scan - PaethPredicator(0, above, 0)) % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
-                else
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    byte left = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
-                    byte above = Unsafe.Add(ref prevBaseRef, x);
-                    byte upperLeft = Unsafe.Add(ref prevBaseRef, x - bytesPerPixel);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)((scan - PaethPredicator(left, above, upperLeft)) % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
+            int x = 0;
+            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - PaethPredictor(0, above, 0));
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
+            }
+
+            for (int xLeft = x - bytesPerPixel; x < scanline.Length; ++xLeft /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                byte left = Unsafe.Add(ref scanBaseRef, xLeft);
+                byte above = Unsafe.Add(ref prevBaseRef, x);
+                byte upperLeft = Unsafe.Add(ref prevBaseRef, xLeft);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - PaethPredictor(left, above, upperLeft));
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
             }
 
             sum -= 4;
@@ -106,7 +106,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
         /// The <see cref="byte"/>.
         /// </returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static byte PaethPredicator(byte left, byte above, byte upperLeft)
+        private static byte PaethPredictor(byte left, byte above, byte upperLeft)
         {
             int p = left + above - upperLeft;
             int pa = ImageMaths.FastAbs(p - left);

src/ImageSharp/Formats/Png/Filters/SubFilter.cs

@@ -25,19 +25,17 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             ref byte scanBaseRef = ref MemoryMarshal.GetReference(scanline);
 
             // Sub(x) + Raw(x-bpp)
-            for (int x = 1; x < scanline.Length; x++)
+            int x = 1;
+            for (; x <= bytesPerPixel /* Note the <= because x starts at 1 */; ++x)
             {
-                if (x - bytesPerPixel < 1)
-                {
-                    ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
-                    scan = (byte)(scan % 256);
-                }
-                else
-                {
-                    ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
-                    byte prev = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
-                    scan = (byte)((scan + prev) % 256);
-                }
+                ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
+            }
+
+            for (; x < scanline.Length; ++x)
+            {
+                ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
+                byte prev = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
+                scan = (byte)(scan + prev);
             }
         }
 
@@ -60,23 +58,22 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             // Sub(x) = Raw(x) - Raw(x-bpp)
             resultBaseRef = 1;
 
-            for (int x = 0; x < scanline.Length; x++)
-            {
-                if (x - bytesPerPixel < 0)
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)(scan % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
-                else
-                {
-                    byte scan = Unsafe.Add(ref scanBaseRef, x);
-                    byte prev = Unsafe.Add(ref scanBaseRef, x - bytesPerPixel);
-                    ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                    res = (byte)((scan - prev) % 256);
-                    sum += res < 128 ? res : 256 - res;
-                }
+            int x = 0;
+            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = scan;
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
+            }
+
+            for (int xLeft = x - bytesPerPixel; x < scanline.Length; ++xLeft /* Note: ++x happens in the body to avoid one add operation */) {
+                byte scan = Unsafe.Add(ref scanBaseRef, x);
+                byte prev = Unsafe.Add(ref scanBaseRef, xLeft);
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - prev);
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
             }
 
             sum -= 1;

src/ImageSharp/Formats/Png/Filters/UpFilter.cs

@@ -32,7 +32,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             {
                 ref byte scan = ref Unsafe.Add(ref scanBaseRef, x);
                 byte above = Unsafe.Add(ref prevBaseRef, x);
-                scan = (byte)((scan + above) % 256);
+                scan = (byte)(scan + above);
             }
         }
 
@@ -57,13 +57,13 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             // Up(x) = Raw(x) - Prior(x)
             resultBaseRef = 2;
 
-            for (int x = 0; x < scanline.Length; x++)
-            {
+            for (int x = 0; x < scanline.Length; /* Note: ++x happens in the body to avoid one add operation */) {
                 byte scan = Unsafe.Add(ref scanBaseRef, x);
                 byte above = Unsafe.Add(ref prevBaseRef, x);
-                ref byte res = ref Unsafe.Add(ref resultBaseRef, x + 1);
-                res = (byte)((scan - above) % 256);
-                sum += res < 128 ? res : 256 - res;
+                ++x;
+                ref byte res = ref Unsafe.Add(ref resultBaseRef, x);
+                res = (byte)(scan - above);
+                sum += ImageMaths.FastAbs(unchecked((sbyte)res));
             }
 
             sum -= 2;

src/ImageSharp/Formats/Png/IPngEncoderOptions.cs

@@ -15,6 +15,11 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         PngColorType PngColorType { get; }
 
+        /// <summary>
+        /// Gets the png filter method.
+        /// </summary>
+        PngFilterMethod PngFilterMethod { get; }
+
         /// <summary>
         /// Gets the compression level 1-9.
         /// <remarks>Defaults to 6.</remarks>

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -853,7 +853,7 @@ namespace SixLabors.ImageSharp.Formats.Png
             where TPixel : struct, IPixel<TPixel>
         {
             ReadOnlySpan<byte> newScanline = ToArrayByBitsLength(defilteredScanline, this.bytesPerScanline, this.header.BitDepth);
-            byte[] pal = this.palette;
+            ReadOnlySpan<Rgb24> pal = MemoryMarshal.Cast<byte, Rgb24>(this.palette);
             var color = default(TPixel);
 
             var rgba = default(Rgba32);
@@ -865,10 +865,9 @@ namespace SixLabors.ImageSharp.Formats.Png
                 for (int x = 0; x < this.header.Width; x++)
                 {
                     int index = newScanline[x];
-                    int pixelOffset = index * 3;
 
                     rgba.A = this.paletteAlpha.Length > index ? this.paletteAlpha[index] : (byte)255;
-                    rgba.Rgb = pal.GetRgb24(pixelOffset);
+                    rgba.Rgb = pal[index];
 
                     color.PackFromRgba32(rgba);
                     row[x] = color;
@@ -881,9 +880,8 @@ namespace SixLabors.ImageSharp.Formats.Png
                 for (int x = 0; x < this.header.Width; x++)
                 {
                     int index = newScanline[x];
-                    int pixelOffset = index * 3;
 
-                    rgba.Rgb = pal.GetRgb24(pixelOffset);
+                    rgba.Rgb = pal[index];
 
                     color.PackFromRgba32(rgba);
                     row[x] = color;
@@ -946,6 +944,7 @@ namespace SixLabors.ImageSharp.Formats.Png
 
                     ReadOnlySpan<byte> newScanline = ToArrayByBitsLength(scanlineBuffer, this.bytesPerScanline, this.header.BitDepth);
                     var rgba = default(Rgba32);
+                    Span<Rgb24> pal = MemoryMarshal.Cast<byte, Rgb24>(this.palette);
 
                     if (this.paletteAlpha != null && this.paletteAlpha.Length > 0)
                     {
@@ -954,10 +953,9 @@ namespace SixLabors.ImageSharp.Formats.Png
                         for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
                         {
                             int index = newScanline[o];
-                            int offset = index * 3;
 
                             rgba.A = this.paletteAlpha.Length > index ? this.paletteAlpha[index] : (byte)255;
-                            rgba.Rgb = this.palette.GetRgb24(offset);
+                            rgba.Rgb = pal[index];
 
                             color.PackFromRgba32(rgba);
                             rowSpan[x] = color;
@@ -970,10 +968,8 @@ namespace SixLabors.ImageSharp.Formats.Png
                         for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
                         {
                             int index = newScanline[o];
-                            int offset = index * 3;
-
-                            rgba.Rgb = this.palette.GetRgb24(offset);
 
+                            rgba.Rgb = pal[index];
                             color.PackFromRgba32(rgba);
                             rowSpan[x] = color;
                         }

src/ImageSharp/Formats/Png/PngEncoder.cs

@@ -14,10 +14,15 @@ namespace SixLabors.ImageSharp.Formats.Png
     public sealed class PngEncoder : IImageEncoder, IPngEncoderOptions
     {
         /// <summary>
-        /// Gets or sets the png color type
+        /// Gets or sets the png color type.
         /// </summary>
         public PngColorType PngColorType { get; set; } = PngColorType.RgbWithAlpha;
 
+        /// <summary>
+        /// Gets or sets the png filter method.
+        /// </summary>
+        public PngFilterMethod PngFilterMethod { get; set; } = PngFilterMethod.Adaptive;
+
         /// <summary>
         /// Gets or sets the compression level 1-9.
         /// <remarks>Defaults to 6.</remarks>

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -46,6 +46,11 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         private readonly PngColorType pngColorType;
 
+        /// <summary>
+        /// The png filter method.
+        /// </summary>
+        private readonly PngFilterMethod pngFilterMethod;
+
         /// <summary>
         /// The quantizer for reducing the color count.
         /// </summary>
@@ -145,6 +150,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         {
             this.memoryManager = memoryManager;
             this.pngColorType = options.PngColorType;
+            this.pngFilterMethod = options.PngFilterMethod;
             this.compressionLevel = options.CompressionLevel;
             this.gamma = options.Gamma;
             this.quantizer = options.Quantizer;
@@ -272,7 +278,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="rowSpan">The row span.</param>
-        private void CollecTPixelBytes<TPixel>(ReadOnlySpan<TPixel> rowSpan)
+        private void CollectTPixelBytes<TPixel>(ReadOnlySpan<TPixel> rowSpan)
             where TPixel : struct, IPixel<TPixel>
         {
             if (this.bytesPerPixel == 4)
@@ -292,7 +298,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="rowSpan">The row span.</param>
         /// <param name="row">The row.</param>
-        /// <returns>The <see cref="T:byte[]"/></returns>
+        /// <returns>The <see cref="IManagedByteBuffer"/></returns>
         private IManagedByteBuffer EncodePixelRow<TPixel>(ReadOnlySpan<TPixel> rowSpan, int row)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -307,11 +313,35 @@ namespace SixLabors.ImageSharp.Formats.Png
                     this.CollectGrayscaleBytes(rowSpan);
                     break;
                 default:
-                    this.CollecTPixelBytes(rowSpan);
+                    this.CollectTPixelBytes(rowSpan);
                     break;
             }
 
-            return this.GetOptimalFilteredScanline();
+            switch (this.pngFilterMethod)
+            {
+                case PngFilterMethod.None:
+                    NoneFilter.Encode(this.rawScanline.Span, this.result.Span);
+                    return this.result;
+
+                case PngFilterMethod.Sub:
+                    SubFilter.Encode(this.rawScanline.Span, this.sub.Span, this.bytesPerPixel, out int _);
+                    return this.sub;
+
+                case PngFilterMethod.Up:
+                    UpFilter.Encode(this.rawScanline.Span, this.previousScanline.Span, this.up.Span, out int _);
+                    return this.up;
+
+                case PngFilterMethod.Average:
+                    AverageFilter.Encode(this.rawScanline.Span, this.previousScanline.Span, this.average.Span, this.bytesPerPixel, out int _);
+                    return this.average;
+
+                case PngFilterMethod.Paeth:
+                    PaethFilter.Encode(this.rawScanline.Span, this.previousScanline.Span, this.paeth.Span, this.bytesPerPixel, out int _);
+                    return this.paeth;
+
+                default:
+                    return this.GetOptimalFilteredScanline();
+            }
         }
 
         /// <summary>
@@ -321,9 +351,6 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <returns>The <see cref="T:byte[]"/></returns>
         private IManagedByteBuffer GetOptimalFilteredScanline()
         {
-            Span<byte> scanSpan = this.rawScanline.Span;
-            Span<byte> prevSpan = this.previousScanline.Span;
-
             // Palette images don't compress well with adaptive filtering.
             if (this.pngColorType == PngColorType.Palette || this.bitDepth < 8)
             {
@@ -331,6 +358,9 @@ namespace SixLabors.ImageSharp.Formats.Png
                 return this.result;
             }
 
+            Span<byte> scanSpan = this.rawScanline.Span;
+            Span<byte> prevSpan = this.previousScanline.Span;
+
             // This order, while different to the enumerated order is more likely to produce a smaller sum
             // early on which shaves a couple of milliseconds off the processing time.
             UpFilter.Encode(scanSpan, prevSpan, this.up.Span, out int currentSum);

src/ImageSharp/Formats/PngFilterMethod.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats
+{
+    /// <summary>
+    /// Provides enumeration of available PNG filter methods.
+    /// </summary>
+    public enum PngFilterMethod
+    {
+        /// <summary>
+        /// With the None filter, the scanline is transmitted unmodified.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// The Sub filter transmits the difference between each byte and the value of the corresponding
+        /// byte of the prior pixel.
+        /// </summary>
+        Sub,
+
+        /// <summary>
+        /// The Up filter is just like the <see cref="Sub"/> filter except that the pixel immediately above the current pixel,
+        /// rather than just to its left, is used as the predictor.
+        /// </summary>
+        Up,
+
+        /// <summary>
+        /// The Average filter uses the average of the two neighboring pixels (left and above) to predict the value of a pixel.
+        /// </summary>
+        Average,
+
+        /// <summary>
+        /// The Paeth filter computes a simple linear function of the three neighboring pixels (left, above, upper left),
+        /// then chooses as predictor the neighboring pixel closest to the computed value.
+        /// </summary>
+        Paeth,
+
+        /// <summary>
+        /// Computes the output scanline using all five filters, and selects the filter that gives the smallest sum of
+        /// absolute values of outputs.
+        /// This method usually outperforms any single fixed filter choice.
+        /// </summary>
+        Adaptive,
+    }
+}

src/ImageSharp/IImageFrameCollection.cs

@@ -1,115 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Collections.Generic;
-
-using SixLabors.ImageSharp.PixelFormats;
-
-namespace SixLabors.ImageSharp
-{
-    /// <summary>
-    /// Encapsulates an imaged collection of frames.
-    /// </summary>
-    /// <typeparam name="TPixel">The type of the pixel.</typeparam>
-    public interface IImageFrameCollection<TPixel> : IEnumerable<ImageFrame<TPixel>>
-        where TPixel : struct, IPixel<TPixel>
-    {
-        /// <summary>
-        /// Gets the count.
-        /// </summary>
-        int Count { get; }
-
-        /// <summary>
-        /// Gets the root frame.
-        /// </summary>
-        ImageFrame<TPixel> RootFrame { get; }
-
-        /// <summary>
-        /// Gets the <see cref="ImageFrame{TPixel}"/> at the specified index.
-        /// </summary>
-        /// <value>
-        /// The <see cref="ImageFrame{TPixel}"/>.
-        /// </value>
-        /// <param name="index">The index.</param>
-        /// <returns>The <see cref="ImageFrame{TPixel}"/> at the specified index.</returns>
-        ImageFrame<TPixel> this[int index] { get; }
-
-        /// <summary>
-        /// Clones the the frame at <paramref name="index"/> and generates a new images with all the same metadata from the orgional but with only the single frame on it.
-        /// </summary>
-        /// <param name="index"> The zero-based index at which item should be removed.</param>
-        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
-        /// <returns>The new <see cref="Image{TPixel}"/> with only the one frame on it.</returns>
-        Image<TPixel> CloneFrame(int index);
-
-        /// <summary>
-        /// Removed the frame at <paramref name="index"/> and generates a new images with all the same metadata from the orgional but with only the single frame on it.
-        /// </summary>
-        /// <param name="index"> The zero-based index at which item should be removed.</param>
-        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
-        /// <returns>The new <see cref="Image{TPixel}"/> with only the one frame on it.</returns>
-        Image<TPixel> ExportFrame(int index);
-
-        /// <summary>
-        /// Remove the frame at <paramref name="index"/> and frees all freeable resources associated with it.
-        /// </summary>
-        /// <param name="index"> The zero-based index at which item should be removed.</param>
-        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
-        void RemoveFrame(int index);
-
-        /// <summary>
-        /// Creates a new <seealso cref="ImageFrame{TPixel}"/> and appends it appends it to the end of the collection.
-        /// </summary>
-        /// <returns>The new <see cref="ImageFrame{TPixel}"/>.</returns>
-        ImageFrame<TPixel> CreateFrame();
-
-        /// <summary>
-        /// Clones the <paramref name="source"/> frame and appends the clone to the end of the collection.
-        /// </summary>
-        /// <param name="source">The raw pixel data to generate <seealso cref="ImageFrame{TPixel}"/> from.</param>
-        /// <returns>The cloned <see cref="ImageFrame{TPixel}"/>.</returns>
-        ImageFrame<TPixel> AddFrame(ImageFrame<TPixel> source);
-
-        /// <summary>
-        /// Creates a new frame from the pixel data at the same dimensions at the current image and inserts the new frame
-        /// into the <seealso cref="Image{TPixel}"/> at the end of the collection.
-        /// </summary>
-        /// <param name="source">The raw pixel data to generate <seealso cref="ImageFrame{TPixel}"/> from.</param>
-        /// <returns>The new <see cref="ImageFrame{TPixel}"/>.</returns>
-        ImageFrame<TPixel> AddFrame(TPixel[] source);
-
-        /// <summary>
-        /// Clones and inserts the <paramref name="source"/> into the <seealso cref="Image{TPixel}"/> at the specified <paramref name="index"/>.
-        /// </summary>
-        /// <param name="index"> The zero-based index at which item should be inserted.</param>
-        /// <param name="source">The <seealso cref="ImageFrame{TPixel}"/> to clone and insert into the <seealso cref="Image{TPixel}"/>.</param>
-        /// <exception cref="ArgumentException">Frame must have the same dimensions as the image - frame</exception>
-        /// <returns>The cloned <see cref="ImageFrame{TPixel}"/>.</returns>
-        ImageFrame<TPixel> InsertFrame(int index, ImageFrame<TPixel> source);
-
-        /// <summary>
-        /// Moves a <seealso cref="ImageFrame{TPixel}"/> from the <seealso cref="Image{TPixel}"/> at the specified index to the other index.
-        /// </summary>
-        /// <param name="sourceIndex">The zero-based index of the item to move.</param>
-        /// <param name="destinationIndex">The zero-based index of the new index that should be inserted at.</param>
-        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
-        void MoveFrame(int sourceIndex, int destinationIndex);
-
-        /// <summary>
-        ///  Determines the index of a specific <paramref name="frame"/> in the <seealso cref="Image{TPixel}"/>.
-        /// </summary>
-        /// <param name="frame">The <seealso cref="ImageFrame{TPixel}"/> to locate in the <seealso cref="Image{TPixel}"/>.</param>
-        /// <returns>The index of item if found in the list; otherwise, -1.</returns>
-        int IndexOf(ImageFrame<TPixel> frame);
-
-        /// <summary>
-        /// Determines whether the <seealso cref="Image{TPixel}"/> contains the <paramref name="frame"/>.
-        /// </summary>
-        /// <param name="frame">The frame.</param>
-        /// <returns>
-        ///   <c>true</c> if the <seealso cref="Image{TPixel}"/> the specified frame; otherwise, <c>false</c>.
-        /// </returns>
-        bool Contains(ImageFrame<TPixel> frame);
-    }
-}

src/ImageSharp/Image.LoadPixelData.cs

@@ -33,7 +33,7 @@ namespace SixLabors.ImageSharp
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        private static Image<TPixel> LoadPixelData<TPixel>(Span<TPixel> data, int width, int height)
+        public static Image<TPixel> LoadPixelData<TPixel>(ReadOnlySpan<TPixel> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
             => LoadPixelData(Configuration.Default, data, width, height);
 
@@ -57,7 +57,7 @@ namespace SixLabors.ImageSharp
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        private static Image<TPixel> LoadPixelData<TPixel>(Span<byte> data, int width, int height)
+        public static Image<TPixel> LoadPixelData<TPixel>(ReadOnlySpan<byte> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
             => LoadPixelData<TPixel>(Configuration.Default, data, width, height);
 
@@ -72,7 +72,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
         public static Image<TPixel> LoadPixelData<TPixel>(Configuration config, byte[] data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
-            => LoadPixelData(config, MemoryMarshal.Cast<byte, TPixel>(data.AsSpan()), width, height);
+            => LoadPixelData(config, MemoryMarshal.Cast<byte, TPixel>(new ReadOnlySpan<byte>(data)), width, height);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given byte array in <typeparamref name="TPixel"/> format.
@@ -83,7 +83,7 @@ namespace SixLabors.ImageSharp
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        private static Image<TPixel> LoadPixelData<TPixel>(Configuration config, Span<byte> data, int width, int height)
+        public static Image<TPixel> LoadPixelData<TPixel>(Configuration config, ReadOnlySpan<byte> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
             => LoadPixelData(config, MemoryMarshal.Cast<byte, TPixel>(data), width, height);
 
@@ -99,7 +99,7 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> LoadPixelData<TPixel>(Configuration config, TPixel[] data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
         {
-            return LoadPixelData(config, data.AsSpan(), width, height);
+            return LoadPixelData(config, new ReadOnlySpan<TPixel>(data), width, height);
         }
 
         /// <summary>
@@ -111,7 +111,7 @@ namespace SixLabors.ImageSharp
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        private static Image<TPixel> LoadPixelData<TPixel>(Configuration config, Span<TPixel> data, int width, int height)
+        public static Image<TPixel> LoadPixelData<TPixel>(Configuration config, ReadOnlySpan<TPixel> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
         {
             int count = width * height;

src/ImageSharp/ImageExtensions.cs

@@ -4,13 +4,11 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Text;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp
 {
@@ -21,18 +19,18 @@ namespace SixLabors.ImageSharp
     {
 #if !NETSTANDARD1_1
         /// <summary>
-        /// Saves the image to the given stream using the currently loaded image format.
+        /// Writes the image to the given stream using the currently loaded image format.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <param name="source">The source image.</param>
         /// <param name="filePath">The file path to save the image to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
         public static void Save<TPixel>(this Image<TPixel> source, string filePath)
             where TPixel : struct, IPixel<TPixel>
         {
-            Guard.NotNullOrEmpty(filePath, nameof(filePath));
+            Guard.NotNullOrWhiteSpace(filePath, nameof(filePath));
 
-            string ext = Path.GetExtension(filePath).Trim('.');
+            string ext = Path.GetExtension(filePath);
             IImageFormat format = source.GetConfiguration().ImageFormatsManager.FindFormatByFileExtension(ext);
             if (format == null)
             {
@@ -64,13 +62,13 @@ namespace SixLabors.ImageSharp
         }
 
         /// <summary>
-        /// Saves the image to the given stream using the currently loaded image format.
+        /// Writes the image to the given stream using the currently loaded image format.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <param name="source">The source image.</param>
         /// <param name="filePath">The file path to save the image to.</param>
         /// <param name="encoder">The encoder to save the image with.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the encoder is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the encoder is null.</exception>
         public static void Save<TPixel>(this Image<TPixel> source, string filePath, IImageEncoder encoder)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -83,13 +81,13 @@ namespace SixLabors.ImageSharp
 #endif
 
         /// <summary>
-        /// Saves the image to the given stream using the currently loaded image format.
+        /// Writes the image to the given stream using the currently loaded image format.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <param name="source">The source image.</param>
         /// <param name="stream">The stream to save the image to.</param>
-        /// <param name="format">The format to save the image to.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <param name="format">The format to save the image in.</param>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static void Save<TPixel>(this Image<TPixel> source, Stream stream, IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -113,67 +111,67 @@ namespace SixLabors.ImageSharp
         }
 
         /// <summary>
-        /// Saves the raw image pixels to a byte array in row-major order.
+        /// Returns the a copy of the image pixels as a byte array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <returns>A copy of the pixel data as bytes from this frame.</returns>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static byte[] SavePixelData<TPixel>(this ImageFrame<TPixel> source)
             where TPixel : struct, IPixel<TPixel>
          => MemoryMarshal.AsBytes(source.GetPixelSpan()).ToArray();
 
         /// <summary>
-        /// Saves the raw image pixels to the given byte array in row-major order.
+        /// Writes the raw image pixels to the given byte array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <param name="source">The source image.</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, byte[] buffer)
             where TPixel : struct, IPixel<TPixel>
             => SavePixelData(source, MemoryMarshal.Cast<byte, TPixel>(buffer.AsSpan()));
 
         /// <summary>
-        /// Saves the raw image pixels to the given TPixel array in row-major order.
+        /// Writes the raw image pixels to the given TPixel array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, TPixel[] buffer)
             where TPixel : struct, IPixel<TPixel>
             => SavePixelData(source, buffer.AsSpan());
 
         /// <summary>
-        /// Saves the raw image pixels to a byte array in row-major order.
+        /// Returns a copy of the raw image pixels as a byte array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <param name="source">The source image.</param>
         /// <returns>A copy of the pixel data from the first frame as bytes.</returns>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static byte[] SavePixelData<TPixel>(this Image<TPixel> source)
             where TPixel : struct, IPixel<TPixel>
          => source.Frames.RootFrame.SavePixelData();
 
         /// <summary>
-        /// Saves the raw image pixels to the given byte array in row-major order.
+        /// Writes the raw image pixels to the given byte array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
-        /// <param name="source">The source image</param>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <param name="source">The source image.</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static void SavePixelData<TPixel>(this Image<TPixel> source, byte[] buffer)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.SavePixelData(buffer);
 
         /// <summary>
-        /// Saves the raw image pixels to the given TPixel array in row-major order.
+        /// Writes the raw image pixels to the given TPixel array in row-major order.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
         public static void SavePixelData<TPixel>(this Image<TPixel> source, TPixel[] buffer)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.SavePixelData(buffer);
@@ -182,7 +180,7 @@ namespace SixLabors.ImageSharp
         /// Returns a Base64 encoded string from the given image.
         /// </summary>
         /// <example><see href="data:image/gif;base64,R0lGODlhAQABAIABAEdJRgAAACwAAAAAAQABAAACAkQBAA=="/></example>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <param name="format">The format.</param>
         /// <returns>The <see cref="string"/></returns>
@@ -198,24 +196,24 @@ namespace SixLabors.ImageSharp
         }
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Writes the raw image bytes to the given byte span.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
-        /// <param name="buffer">The buffer to save the raw pixel data to.</param>
+        /// <param name="buffer">The span to save the raw pixel data to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
-        internal static void SavePixelData<TPixel>(this Image<TPixel> source, Span<byte> buffer)
+        public static void SavePixelData<TPixel>(this Image<TPixel> source, Span<byte> buffer)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.SavePixelData(MemoryMarshal.Cast<byte, TPixel>(buffer));
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Writes the raw image pixels to the given TPixel span.
         /// </summary>
-        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="source">The source image</param>
-        /// <param name="buffer">The buffer to save the raw pixel data to.</param>
+        /// <param name="buffer">The span to save the raw pixel data to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
-        internal static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, Span<TPixel> buffer)
+        public static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, Span<TPixel> buffer)
             where TPixel : struct, IPixel<TPixel>
         {
             Span<TPixel> sourceBuffer = source.GetPixelSpan();
@@ -224,4 +222,4 @@ namespace SixLabors.ImageSharp
             sourceBuffer.CopyTo(buffer);
         }
     }
-}
+}

src/ImageSharp/ImageFrame.LoadPixelData.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp
@@ -12,37 +11,37 @@ namespace SixLabors.ImageSharp
     /// <content>
     /// Adds static methods allowing the creation of new image from raw pixel data.
     /// </content>
-    internal static partial class ImageFrame
+    internal static class ImageFrame
     {
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given byte array in <typeparamref name="TPixel"/> format.
         /// </summary>
-        /// <param name="memoryManager">The memory manager to use for allocations</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
         /// <param name="data">The byte array containing image data.</param>
         /// <param name="width">The width of the final image.</param>
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        public static ImageFrame<TPixel> LoadPixelData<TPixel>(MemoryManager memoryManager, Span<byte> data, int width, int height)
+        public static ImageFrame<TPixel> LoadPixelData<TPixel>(Configuration configuration, ReadOnlySpan<byte> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
-            => LoadPixelData(memoryManager, MemoryMarshal.Cast<byte, TPixel>(data), width, height);
+            => LoadPixelData(configuration, MemoryMarshal.Cast<byte, TPixel>(data), width, height);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the raw <typeparamref name="TPixel"/> data.
         /// </summary>
-        /// <param name="memoryManager">The memory manager to use for allocations</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
         /// <param name="data">The Span containing the image Pixel data.</param>
         /// <param name="width">The width of the final image.</param>
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        public static ImageFrame<TPixel> LoadPixelData<TPixel>(MemoryManager memoryManager, Span<TPixel> data, int width, int height)
+        public static ImageFrame<TPixel> LoadPixelData<TPixel>(Configuration configuration, ReadOnlySpan<TPixel> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
         {
             int count = width * height;
             Guard.MustBeGreaterThanOrEqualTo(data.Length, count, nameof(data));
 
-            var image = new ImageFrame<TPixel>(memoryManager, width, height);
+            var image = new ImageFrame<TPixel>(configuration, width, height);
 
             data.Slice(0, count).CopyTo(image.GetPixelSpan());
 

src/ImageSharp/ImageFrameCollection.cs

@@ -10,29 +10,29 @@ using SixLabors.ImageSharp.PixelFormats;
 namespace SixLabors.ImageSharp
 {
     /// <summary>
-    /// Encapsulates a collection of frames that make up an image.
+    /// Encapsulates a collection of <see cref="ImageFrame{T}"/> instances that make up an <see cref="Image{T}"/>.
     /// </summary>
     /// <typeparam name="TPixel">The type of the pixel.</typeparam>
-    internal sealed class ImageFrameCollection<TPixel> : IImageFrameCollection<TPixel>
+    public sealed class ImageFrameCollection<TPixel> : IEnumerable<ImageFrame<TPixel>>
         where TPixel : struct, IPixel<TPixel>
     {
         private readonly IList<ImageFrame<TPixel>> frames = new List<ImageFrame<TPixel>>();
         private readonly Image<TPixel> parent;
 
-        internal ImageFrameCollection(Image<TPixel> parent, int width, int height)
+        internal ImageFrameCollection(Image<TPixel> parent, int width, int height, TPixel backgroundColor)
         {
             Guard.NotNull(parent, nameof(parent));
 
             this.parent = parent;
 
             // Frames are already cloned within the caller
-            this.frames.Add(new ImageFrame<TPixel>(parent.GetConfiguration().MemoryManager, width, height));
+            this.frames.Add(new ImageFrame<TPixel>(parent.GetConfiguration(), width, height, backgroundColor));
         }
 
         internal ImageFrameCollection(Image<TPixel> parent, IEnumerable<ImageFrame<TPixel>> frames)
         {
             Guard.NotNull(parent, nameof(parent));
-            Guard.NotNullOrEmpty(frames, nameof(frames));
+            Guard.NotNull(frames, nameof(frames));
 
             this.parent = parent;
 
@@ -42,53 +42,93 @@ namespace SixLabors.ImageSharp
                 this.ValidateFrame(f);
                 this.frames.Add(f);
             }
+
+            // Ensure at least 1 frame was added to the frames collection
+            if (this.frames.Count == 0)
+            {
+                throw new ArgumentException("Must not be empty.", nameof(frames));
+            }
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Gets the number of frames.
+        /// </summary>
         public int Count => this.frames.Count;
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Gets the root frame.
+        /// </summary>
         public ImageFrame<TPixel> RootFrame => this.frames.Count > 0 ? this.frames[0] : null;
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Gets the <see cref="ImageFrame{TPixel}"/> at the specified index.
+        /// </summary>
+        /// <value>
+        /// The <see cref="ImageFrame{TPixel}"/>.
+        /// </value>
+        /// <param name="index">The index.</param>
+        /// <returns>The <see cref="ImageFrame{TPixel}"/> at the specified index.</returns>
         public ImageFrame<TPixel> this[int index] => this.frames[index];
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Determines the index of a specific <paramref name="frame"/> in the <seealso cref="ImageFrameCollection{TPixel}"/>.
+        /// </summary>
+        /// <param name="frame">The <seealso cref="ImageFrame{TPixel}"/> to locate in the <seealso cref="ImageFrameCollection{TPixel}"/>.</param>
+        /// <returns>The index of item if found in the list; otherwise, -1.</returns>
         public int IndexOf(ImageFrame<TPixel> frame) => this.frames.IndexOf(frame);
 
-        /// <inheritdoc/>
-        public ImageFrame<TPixel> InsertFrame(int index, ImageFrame<TPixel> frame)
+        /// <summary>
+        /// Clones and inserts the <paramref name="source"/> into the <seealso cref="ImageFrameCollection{TPixel}"/> at the specified <paramref name="index"/>.
+        /// </summary>
+        /// <param name="index">The zero-based index to insert the frame at.</param>
+        /// <param name="source">The <seealso cref="ImageFrame{TPixel}"/> to clone and insert into the <seealso cref="ImageFrameCollection{TPixel}"/>.</param>
+        /// <exception cref="ArgumentException">Frame must have the same dimensions as the image.</exception>
+        /// <returns>The cloned <see cref="ImageFrame{TPixel}"/>.</returns>
+        public ImageFrame<TPixel> InsertFrame(int index, ImageFrame<TPixel> source)
         {
-            this.ValidateFrame(frame);
-            ImageFrame<TPixel> clonedFrame = frame.Clone();
+            this.ValidateFrame(source);
+            ImageFrame<TPixel> clonedFrame = source.Clone();
             this.frames.Insert(index, clonedFrame);
             return clonedFrame;
         }
 
-        /// <inheritdoc/>
-        public ImageFrame<TPixel> AddFrame(ImageFrame<TPixel> frame)
+        /// <summary>
+        /// Clones the <paramref name="source"/> frame and appends the clone to the end of the collection.
+        /// </summary>
+        /// <param name="source">The raw pixel data to generate the <seealso cref="ImageFrame{TPixel}"/> from.</param>
+        /// <returns>The cloned <see cref="ImageFrame{TPixel}"/>.</returns>
+        public ImageFrame<TPixel> AddFrame(ImageFrame<TPixel> source)
         {
-            this.ValidateFrame(frame);
-            ImageFrame<TPixel> clonedFrame = frame.Clone();
+            this.ValidateFrame(source);
+            ImageFrame<TPixel> clonedFrame = source.Clone();
             this.frames.Add(clonedFrame);
             return clonedFrame;
         }
 
-        /// <inheritdoc/>
-        public ImageFrame<TPixel> AddFrame(TPixel[] data)
+        /// <summary>
+        /// Creates a new frame from the pixel data with the same dimensions as the other frames and inserts the
+        /// new frame at the end of the collection.
+        /// </summary>
+        /// <param name="source">The raw pixel data to generate the <seealso cref="ImageFrame{TPixel}"/> from.</param>
+        /// <returns>The new <see cref="ImageFrame{TPixel}"/>.</returns>
+        public ImageFrame<TPixel> AddFrame(TPixel[] source)
         {
-            Guard.NotNull(data, nameof(data));
+            Guard.NotNull(source, nameof(source));
 
             var frame = ImageFrame.LoadPixelData(
-                this.parent.GetMemoryManager(),
-                new Span<TPixel>(data),
+                this.parent.GetConfiguration(),
+                new ReadOnlySpan<TPixel>(source),
                 this.RootFrame.Width,
                 this.RootFrame.Height);
             this.frames.Add(frame);
             return frame;
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Removes the frame at the specified index and frees all freeable resources associated with it.
+        /// </summary>
+        /// <param name="index">The zero-based index of the frame to remove.</param>
+        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
         public void RemoveFrame(int index)
         {
             if (index == 0 && this.Count == 1)
@@ -101,26 +141,42 @@ namespace SixLabors.ImageSharp
             frame.Dispose();
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Determines whether the <seealso cref="ImageFrameCollection{TPixel}"/> contains the <paramref name="frame"/>.
+        /// </summary>
+        /// <param name="frame">The frame.</param>
+        /// <returns>
+        ///   <c>true</c> if the <seealso cref="ImageFrameCollection{TPixel}"/> contains the specified frame; otherwise, <c>false</c>.
+        /// </returns>
         public bool Contains(ImageFrame<TPixel> frame)
         {
             return this.frames.Contains(frame);
         }
 
-        /// <inheritdoc/>
-        public void MoveFrame(int sourceIndex, int destIndex)
+        /// <summary>
+        /// Moves an <seealso cref="ImageFrame{TPixel}"/> from <paramref name="sourceIndex"/> to <paramref name="destinationIndex"/>.
+        /// </summary>
+        /// <param name="sourceIndex">The zero-based index of the frame to move.</param>
+        /// <param name="destinationIndex">The index to move the frame to.</param>
+        public void MoveFrame(int sourceIndex, int destinationIndex)
         {
-            if (sourceIndex == destIndex)
+            if (sourceIndex == destinationIndex)
             {
                 return;
             }
 
             ImageFrame<TPixel> frameAtIndex = this.frames[sourceIndex];
             this.frames.RemoveAt(sourceIndex);
-            this.frames.Insert(destIndex, frameAtIndex);
+            this.frames.Insert(destinationIndex, frameAtIndex);
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Removes the frame at the specified index and creates a new image with only the removed frame
+        /// with the same metadata as the original image.
+        /// </summary>
+        /// <param name="index">The zero-based index of the frame to export.</param>
+        /// <exception cref="InvalidOperationException">Cannot remove last frame.</exception>
+        /// <returns>The new <see cref="Image{TPixel}"/> with the specified frame.</returns>
         public Image<TPixel> ExportFrame(int index)
         {
             ImageFrame<TPixel> frame = this[index];
@@ -135,7 +191,12 @@ namespace SixLabors.ImageSharp
             return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.Clone(), new[] { frame });
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Creates an <see cref="Image{T}"/> with only the frame at the specified index
+        /// with the same metadata as the original image.
+        /// </summary>
+        /// <param name="index">The zero-based index of the frame to clone.</param>
+        /// <returns>The new <see cref="Image{TPixel}"/> with the specified frame.</returns>
         public Image<TPixel> CloneFrame(int index)
         {
             ImageFrame<TPixel> frame = this[index];
@@ -143,10 +204,31 @@ namespace SixLabors.ImageSharp
             return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.Clone(), new[] { clonedFrame });
         }
 
-        /// <inheritdoc/>
+        /// <summary>
+        /// Creates a new <seealso cref="ImageFrame{TPixel}" /> and appends it to the end of the collection.
+        /// </summary>
+        /// <returns>
+        /// The new <see cref="ImageFrame{TPixel}" />.
+        /// </returns>
         public ImageFrame<TPixel> CreateFrame()
         {
-            var frame = new ImageFrame<TPixel>(this.parent.GetConfiguration().MemoryManager, this.RootFrame.Width, this.RootFrame.Height);
+            return this.CreateFrame(default);
+        }
+
+        /// <summary>
+        /// Creates a new <seealso cref="ImageFrame{TPixel}" /> and appends it to the end of the collection.
+        /// </summary>
+        /// <param name="backgroundColor">The background color to initialize the pixels with.</param>
+        /// <returns>
+        /// The new <see cref="ImageFrame{TPixel}" />.
+        /// </returns>
+        public ImageFrame<TPixel> CreateFrame(TPixel backgroundColor)
+        {
+            var frame = new ImageFrame<TPixel>(
+                this.parent.GetConfiguration(),
+                this.RootFrame.Width,
+                this.RootFrame.Height,
+                backgroundColor);
             this.frames.Add(frame);
             return frame;
         }

src/ImageSharp/ImageFrame{TPixel}.cs

@@ -20,58 +20,90 @@ namespace SixLabors.ImageSharp
     public sealed class ImageFrame<TPixel> : IPixelSource<TPixel>, IDisposable
         where TPixel : struct, IPixel<TPixel>
     {
+        private readonly Configuration configuration;
         private bool isDisposed;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
         /// </summary>
-        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
         /// <param name="width">The width of the image in pixels.</param>
         /// <param name="height">The height of the image in pixels.</param>
-        internal ImageFrame(MemoryManager memoryManager, int width, int height)
-            : this(memoryManager, width, height, new ImageFrameMetaData())
+        internal ImageFrame(Configuration configuration, int width, int height)
+            : this(configuration, width, height, new ImageFrameMetaData())
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
         /// </summary>
-        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
+        /// <param name="size">The <see cref="Size"/> of the frame.</param>
+        /// <param name="metaData">The meta data.</param>
+        internal ImageFrame(Configuration configuration, Size size, ImageFrameMetaData metaData)
+            : this(configuration, size.Width, size.Height, metaData)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
+        /// </summary>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
         /// <param name="width">The width of the image in pixels.</param>
         /// <param name="height">The height of the image in pixels.</param>
         /// <param name="metaData">The meta data.</param>
-        internal ImageFrame(MemoryManager memoryManager, int width, int height, ImageFrameMetaData metaData)
+        internal ImageFrame(Configuration configuration, int width, int height, ImageFrameMetaData metaData)
+            : this(configuration, width, height, default, metaData)
         {
-            Guard.NotNull(memoryManager, nameof(memoryManager));
-            Guard.MustBeGreaterThan(width, 0, nameof(width));
-            Guard.MustBeGreaterThan(height, 0, nameof(height));
-            Guard.NotNull(metaData, nameof(metaData));
+        }
 
-            this.MemoryManager = memoryManager;
-            this.PixelBuffer = memoryManager.AllocateClean2D<TPixel>(width, height);
-            this.MetaData = metaData;
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
+        /// </summary>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
+        /// <param name="width">The width of the image in pixels.</param>
+        /// <param name="height">The height of the image in pixels.</param>
+        /// <param name="backgroundColor">The color to clear the image with.</param>
+        internal ImageFrame(Configuration configuration, int width, int height, TPixel backgroundColor)
+            : this(configuration, width, height, backgroundColor, new ImageFrameMetaData())
+        {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
         /// </summary>
-        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
-        /// <param name="size">The <see cref="Size"/> of the frame.</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
+        /// <param name="width">The width of the image in pixels.</param>
+        /// <param name="height">The height of the image in pixels.</param>
+        /// <param name="backgroundColor">The color to clear the image with.</param>
         /// <param name="metaData">The meta data.</param>
-        internal ImageFrame(MemoryManager memoryManager, Size size, ImageFrameMetaData metaData)
-            : this(memoryManager, size.Width, size.Height, metaData)
+        internal ImageFrame(Configuration configuration, int width, int height, TPixel backgroundColor, ImageFrameMetaData metaData)
         {
+            Guard.NotNull(configuration, nameof(configuration));
+            Guard.MustBeGreaterThan(width, 0, nameof(width));
+            Guard.MustBeGreaterThan(height, 0, nameof(height));
+            Guard.NotNull(metaData, nameof(metaData));
+
+            this.configuration = configuration;
+            this.MemoryManager = configuration.MemoryManager;
+            this.PixelBuffer = this.MemoryManager.Allocate2D<TPixel>(width, height, false);
+            this.MetaData = metaData;
+            this.Clear(configuration.ParallelOptions, backgroundColor);
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class.
         /// </summary>
-        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
+        /// <param name="configuration">The configuration which allows altering default behaviour or extending the library.</param>
         /// <param name="source">The source.</param>
-        internal ImageFrame(MemoryManager memoryManager, ImageFrame<TPixel> source)
+        internal ImageFrame(Configuration configuration, ImageFrame<TPixel> source)
         {
-            this.MemoryManager = memoryManager;
-            this.PixelBuffer = memoryManager.Allocate2D<TPixel>(source.PixelBuffer.Width, source.PixelBuffer.Height);
+            Guard.NotNull(configuration, nameof(configuration));
+            Guard.NotNull(source, nameof(source));
+
+            this.configuration = configuration;
+            this.MemoryManager = configuration.MemoryManager;
+            this.PixelBuffer = this.MemoryManager.Allocate2D<TPixel>(source.PixelBuffer.Width, source.PixelBuffer.Height);
             source.PixelBuffer.Span.CopyTo(this.PixelBuffer.Span);
             this.MetaData = source.MetaData.Clone();
         }
@@ -246,13 +278,12 @@ namespace SixLabors.ImageSharp
                 return this.Clone() as ImageFrame<TPixel2>;
             }
 
-            var target = new ImageFrame<TPixel2>(this.MemoryManager, this.Width, this.Height, this.MetaData.Clone());
+            var target = new ImageFrame<TPixel2>(this.configuration, this.Width, this.Height, this.MetaData.Clone());
 
-            // TODO: ImageFrame has no visibility of the current configuration. It should have.
             ParallelFor.WithTemporaryBuffer(
                 0,
                 this.Height,
-                Configuration.Default,
+                this.configuration,
                 this.Width,
                 (int y, IBuffer<Vector4> tempRowBuffer) =>
                 {
@@ -267,13 +298,31 @@ namespace SixLabors.ImageSharp
             return target;
         }
 
+        /// <summary>
+        /// Clears the bitmap.
+        /// </summary>
+        /// <param name="parallelOptions">The parallel options.</param>
+        /// <param name="value">The value to initialize the bitmap with.</param>
+        internal void Clear(ParallelOptions parallelOptions, TPixel value)
+        {
+            Parallel.For(
+                0,
+                this.Height,
+                parallelOptions,
+                y =>
+                {
+                    Span<TPixel> targetRow = this.GetPixelRowSpan(y);
+                    targetRow.Fill(value);
+                });
+        }
+
         /// <summary>
         /// Clones the current instance.
         /// </summary>
         /// <returns>The <see cref="ImageFrame{TPixel}"/></returns>
         internal ImageFrame<TPixel> Clone()
         {
-            return new ImageFrame<TPixel>(this.MemoryManager, this);
+            return new ImageFrame<TPixel>(this.configuration, this);
         }
 
         /// <inheritdoc/>

src/ImageSharp/ImageSharp.csproj

@@ -41,8 +41,8 @@
       <PrivateAssets>All</PrivateAssets>
     </PackageReference>
     <PackageReference Include="System.Buffers" Version="4.4.0" />
-    <PackageReference Include="System.Memory" Version="4.5.0-preview2-26406-04" />
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.0-preview2-26406-04" />
+    <PackageReference Include="System.Memory" Version="4.5.0-rc1" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.0-rc1" />
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.1' OR '$(TargetFramework)' == 'netstandard1.3'">
     <PackageReference Include="System.IO.Compression" Version="4.3.0" />
@@ -57,11 +57,11 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
   <ItemGroup>
-    <None Update="Formats\Jpeg\Common\Block8x8F.Generated.tt">
+    <None Update="Formats\Jpeg\Components\Block8x8F.Generated.tt">
       <Generator>TextTemplatingFileGenerator</Generator>
       <LastGenOutput>Block8x8F.Generated.cs</LastGenOutput>
     </None>
-    <None Update="Formats\Jpeg\Common\GenericBlock8x8.Generated.tt">
+    <None Update="Formats\Jpeg\Components\GenericBlock8x8.Generated.tt">
       <Generator>TextTemplatingFileGenerator</Generator>
       <LastGenOutput>GenericBlock8x8.Generated.cs</LastGenOutput>
     </None>
@@ -87,12 +87,12 @@
     </None>
   </ItemGroup>
   <ItemGroup>
-    <Compile Update="Formats\Jpeg\Common\Block8x8F.Generated.cs">
+    <Compile Update="Formats\Jpeg\Components\Block8x8F.Generated.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
       <DependentUpon>Block8x8F.Generated.tt</DependentUpon>
     </Compile>
-    <Compile Update="Formats\Jpeg\Common\GenericBlock8x8.Generated.cs">
+    <Compile Update="Formats\Jpeg\Components\GenericBlock8x8.Generated.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
       <DependentUpon>GenericBlock8x8.Generated.tt</DependentUpon>
@@ -123,4 +123,7 @@
       <DependentUpon>PorterDuffFunctions.Generated.tt</DependentUpon>
     </Compile>
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
+  </ItemGroup>
 </Project>

src/ImageSharp/Image{TPixel}.cs

@@ -37,6 +37,21 @@ namespace SixLabors.ImageSharp
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
+        /// with the height and the width of the image.
+        /// </summary>
+        /// <param name="configuration">
+        /// The configuration providing initialization code which allows extending the library.
+        /// </param>
+        /// <param name="width">The width of the image in pixels.</param>
+        /// <param name="height">The height of the image in pixels.</param>
+        /// <param name="backgroundColor">The color to initialize the pixels with.</param>
+        public Image(Configuration configuration, int width, int height, TPixel backgroundColor)
+            : this(configuration, width, height, backgroundColor, new ImageMetaData())
+        {
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
         /// with the height and the width of the image.
@@ -63,7 +78,25 @@ namespace SixLabors.ImageSharp
             this.configuration = configuration ?? Configuration.Default;
             this.PixelType = new PixelTypeInfo(Unsafe.SizeOf<TPixel>() * 8);
             this.MetaData = metadata ?? new ImageMetaData();
-            this.frames = new ImageFrameCollection<TPixel>(this, width, height);
+            this.frames = new ImageFrameCollection<TPixel>(this, width, height, default);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
+        /// with the height and the width of the image.
+        /// </summary>
+        /// <param name="configuration">
+        /// The configuration providing initialization code which allows extending the library.
+        /// </param>
+        /// <param name="width">The width of the image in pixels.</param>
+        /// <param name="height">The height of the image in pixels.</param>
+        /// <param name="backgroundColor">The color to initialize the pixels with.</param>
+        /// <param name="metadata">The images metadata.</param>
+        internal Image(Configuration configuration, int width, int height, TPixel backgroundColor, ImageMetaData metadata) {
+            this.configuration = configuration ?? Configuration.Default;
+            this.PixelType = new PixelTypeInfo(Unsafe.SizeOf<TPixel>() * 8);
+            this.MetaData = metadata ?? new ImageMetaData();
+            this.frames = new ImageFrameCollection<TPixel>(this, width, height, backgroundColor);
         }
 
         /// <summary>
@@ -102,7 +135,7 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Gets the frames.
         /// </summary>
-        public IImageFrameCollection<TPixel> Frames => this.frames;
+        public ImageFrameCollection<TPixel> Frames => this.frames;
 
         /// <summary>
         /// Gets the root frame.

src/ImageSharp/Memory/SpanHelper.cs

@@ -1,48 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Runtime.CompilerServices;
-
-namespace SixLabors.ImageSharp.Memory
-{
-    /// <summary>
-    /// Utility methods for <see cref="Span{T}"/>
-    /// </summary>
-    internal static class SpanHelper
-    {
-        /// <summary>
-        /// Copy all elements of 'source' into 'destination'.
-        /// </summary>
-        /// <typeparam name="T">The element type.</typeparam>
-        /// <param name="source">The <see cref="Span{T}"/> to copy elements from.</param>
-        /// <param name="destination">The destination <see cref="Span{T}"/>.</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Copy<T>(ReadOnlySpan<T> source, Span<T> destination)
-            where T : struct
-        {
-            source.Slice(0, Math.Min(source.Length, destination.Length)).CopyTo(destination);
-        }
-
-        /// <summary>
-        /// Gets the size of `count` elements in bytes.
-        /// </summary>
-        /// <typeparam name="T">The element type.</typeparam>
-        /// <param name="count">The count of the elements</param>
-        /// <returns>The size in bytes as int</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static int SizeOf<T>(int count)
-            where T : struct => Unsafe.SizeOf<T>() * count;
-
-        /// <summary>
-        /// Gets the size of `count` elements in bytes as UInt32
-        /// </summary>
-        /// <typeparam name="T">The element type.</typeparam>
-        /// <param name="count">The count of the elements</param>
-        /// <returns>The size in bytes as UInt32</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static uint USizeOf<T>(int count)
-            where T : struct
-            => (uint)SizeOf<T>(count);
-    }
-}