Merge branch 'master' into colorspace-transforms

README.md

@@ -70,6 +70,9 @@ Our API is designed to be simple to consume. Here's an example of the code requi
 On platforms supporting netstandard 1.3+
 
 ```csharp
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Processing;
+
 // Image.Load(string path) is a shortcut for our default type. 
 // Other pixel formats use Image.Load<TPixel>(string path))
 using (Image<Rgba32> image = Image.Load("foo.jpg"))
@@ -83,6 +86,9 @@ using (Image<Rgba32> image = Image.Load("foo.jpg"))
 On netstandard 1.1 - 1.2
 
 ```csharp
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Processing;
+
 // Image.Load(Stream stream) is a shortcut for our default type.
 // Other pixel formats use Image.Load<TPixel>(Stream stream))
 using (FileStream stream = File.OpenRead("foo.jpg"))
@@ -99,6 +105,9 @@ using (Image<Rgba32> image = Image.Load(stream))
 Setting individual pixel values can be performed as follows:
 
 ```csharp
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+
 // Individual pixels
 using (Image<Rgba32> image = new Image<Rgba32>(400, 400))
 {

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

@@ -1,95 +1,101 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Buffers;
-using System.Threading.Tasks;
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Memory;
-using SixLabors.Primitives;
-
-namespace SixLabors.ImageSharp.Processing.Processors.Drawing
-{
-    /// <summary>
-    /// Combines two images together by blending the pixels.
-    /// </summary>
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers;
+using System.Threading.Tasks;
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Memory;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors.Drawing
+{
+    /// <summary>
+    /// Combines two images together by blending the pixels.
+    /// </summary>
     /// <typeparam name="TPixelDst">The pixel format of destination image.</typeparam>
-    /// <typeparam name="TPixelSrc">The pixel format os source image.</typeparam>
-    internal class DrawImageProcessor<TPixelDst, TPixelSrc> : ImageProcessor<TPixelDst>
+    /// <typeparam name="TPixelSrc">The pixel format of source image.</typeparam>
+    internal class DrawImageProcessor<TPixelDst, TPixelSrc> : ImageProcessor<TPixelDst>
         where TPixelDst : struct, IPixel<TPixelDst>
-        where TPixelSrc : struct, IPixel<TPixelSrc>
+        where TPixelSrc : struct, IPixel<TPixelSrc>
     {
-        /// <summary>
-        /// Initializes a new instance of the <see cref="DrawImageProcessor{TPixelDst, TPixelSrc}"/> class.
-        /// </summary>
-        /// <param name="image">The image to blend with the currently processing image.</param>
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DrawImageProcessor{TPixelDst, TPixelSrc}"/> class.
+        /// </summary>
+        /// <param name="image">The image to blend with the currently processing image.</param>
         /// <param name="location">The location to draw the blended image.</param>
         /// <param name="colorBlendingMode">The blending mode to use when drawing the image.</param>
         /// <param name="alphaCompositionMode">The Alpha blending mode to use when drawing the image.</param>
-        /// <param name="opacity">The opacity of the image to blend. Must be between 0 and 1.</param>
-        public DrawImageProcessor(Image<TPixelSrc> image, Point location, PixelColorBlendingMode colorBlendingMode, PixelAlphaCompositionMode alphaCompositionMode, float opacity)
-        {
-            Guard.MustBeBetweenOrEqualTo(opacity, 0, 1, nameof(opacity));
-
-            this.Image = image;
-            this.Opacity = opacity;
-            this.Blender = PixelOperations<TPixelDst>.Instance.GetPixelBlender(colorBlendingMode, alphaCompositionMode);
-            this.Location = location;
-        }
-
-        /// <summary>
-        /// Gets the image to blend
-        /// </summary>
-        public Image<TPixelSrc> Image { get; }
-
-        /// <summary>
-        /// Gets the opacity of the image to blend
-        /// </summary>
-        public float Opacity { get; }
-
-        /// <summary>
-        /// Gets the pixel blender
-        /// </summary>
-        public PixelBlender<TPixelDst> Blender { get; }
-
-        /// <summary>
-        /// Gets the location to draw the blended image
-        /// </summary>
-        public Point Location { get; }
-
-        /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixelDst> source, Rectangle sourceRectangle, Configuration configuration)
-        {
-            Image<TPixelSrc> targetImage = this.Image;
-            PixelBlender<TPixelDst> blender = this.Blender;
-            int locationY = this.Location.Y;
-
-            // Align start/end positions.
-            Rectangle bounds = targetImage.Bounds();
-
-            int minX = Math.Max(this.Location.X, sourceRectangle.X);
-            int maxX = Math.Min(this.Location.X + bounds.Width, sourceRectangle.Width);
-            int targetX = minX - this.Location.X;
-
-            int minY = Math.Max(this.Location.Y, sourceRectangle.Y);
-            int maxY = Math.Min(this.Location.Y + bounds.Height, sourceRectangle.Bottom);
-
-            int width = maxX - minX;
-
+        /// <param name="opacity">The opacity of the image to blend. Must be between 0 and 1.</param>
+        public DrawImageProcessor(Image<TPixelSrc> image, Point location, PixelColorBlendingMode colorBlendingMode, PixelAlphaCompositionMode alphaCompositionMode, float opacity)
+        {
+            Guard.MustBeBetweenOrEqualTo(opacity, 0, 1, nameof(opacity));
+
+            this.Image = image;
+            this.Opacity = opacity;
+            this.Blender = PixelOperations<TPixelDst>.Instance.GetPixelBlender(colorBlendingMode, alphaCompositionMode);
+            this.Location = location;
+        }
+
+        /// <summary>
+        /// Gets the image to blend
+        /// </summary>
+        public Image<TPixelSrc> Image { get; }
+
+        /// <summary>
+        /// Gets the opacity of the image to blend
+        /// </summary>
+        public float Opacity { get; }
+
+        /// <summary>
+        /// Gets the pixel blender
+        /// </summary>
+        public PixelBlender<TPixelDst> Blender { get; }
+
+        /// <summary>
+        /// Gets the location to draw the blended image
+        /// </summary>
+        public Point Location { get; }
+
+        /// <inheritdoc/>
+        protected override void OnFrameApply(ImageFrame<TPixelDst> source, Rectangle sourceRectangle, Configuration configuration)
+        {
+            Image<TPixelSrc> targetImage = this.Image;
+            PixelBlender<TPixelDst> blender = this.Blender;
+            int locationY = this.Location.Y;
+
+            // Align start/end positions.
+            Rectangle bounds = targetImage.Bounds();
+
+            int minX = Math.Max(this.Location.X, sourceRectangle.X);
+            int maxX = Math.Min(this.Location.X + bounds.Width, sourceRectangle.Width);
+            int targetX = minX - this.Location.X;
+
+            int minY = Math.Max(this.Location.Y, sourceRectangle.Y);
+            int maxY = Math.Min(this.Location.Y + bounds.Height, sourceRectangle.Bottom);
+
+            int width = maxX - minX;
+
             MemoryAllocator memoryAllocator = this.Image.GetConfiguration().MemoryAllocator;
 
-            ParallelFor.WithConfiguration(
-                minY,
-                maxY,
-                configuration,
-                y =>
-                    {
-                        Span<TPixelDst> background = source.GetPixelRowSpan(y).Slice(minX, width);
-                        Span<TPixelSrc> foreground = targetImage.GetPixelRowSpan(y - locationY).Slice(targetX, width);
-                        blender.Blend<TPixelSrc>(memoryAllocator, background, background, foreground, this.Opacity);
-                    });
-        }
-    }
+            var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
+            ParallelHelper.IterateRows(
+                workingRect,
+                configuration,
+                rows =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            Span<TPixelDst> background = source.GetPixelRowSpan(y).Slice(minX, width);
+                            Span<TPixelSrc> foreground =
+                                targetImage.GetPixelRowSpan(y - locationY).Slice(targetX, width);
+                            blender.Blend<TPixelSrc>(memoryAllocator, background, background, foreground, this.Opacity);
+                        }
+                    });
+        }
+    }
 }

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

@@ -1,107 +1,116 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Buffers;
-using System.Threading.Tasks;
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Memory;
-using SixLabors.Primitives;
-
-namespace SixLabors.ImageSharp.Processing.Processors.Drawing
-{
-    /// <summary>
-    /// Using the brush as a source of pixels colors blends the brush color with source.
-    /// </summary>
-    /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class FillProcessor<TPixel> : ImageProcessor<TPixel>
-        where TPixel : struct, IPixel<TPixel>
-    {
-        /// <summary>
-        /// The brush.
-        /// </summary>
-        private readonly IBrush<TPixel> brush;
-        private readonly GraphicsOptions options;
-
-        /// <summary>
-        /// Initializes a new instance of the <see cref="FillProcessor{TPixel}"/> class.
-        /// </summary>
-        /// <param name="brush">The brush to source pixel colors from.</param>
-        /// <param name="options">The options</param>
-        public FillProcessor(IBrush<TPixel> brush, GraphicsOptions options)
-        {
-            this.brush = brush;
-            this.options = options;
-        }
-
-        /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
-        {
-            int startX = sourceRectangle.X;
-            int endX = sourceRectangle.Right;
-            int startY = sourceRectangle.Y;
-            int endY = sourceRectangle.Bottom;
-
-            // Align start/end positions.
-            int minX = Math.Max(0, startX);
-            int maxX = Math.Min(source.Width, endX);
-            int minY = Math.Max(0, startY);
-            int maxY = Math.Min(source.Height, endY);
-
-            int width = maxX - minX;
-
-            // If there's no reason for blending, then avoid it.
-            if (this.IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush))
-            {
-                ParallelFor.WithConfiguration(
-                    minY,
-                    maxY,
-                    configuration,
-                    y =>
-                    {
-                        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 (IMemoryOwner<float> amount = source.MemoryAllocator.Allocate<float>(width))
-                using (BrushApplicator<TPixel> applicator = this.brush.CreateApplicator(
-                    source,
-                    sourceRectangle,
-                    this.options))
-                {
-                    amount.GetSpan().Fill(1f);
-
-                    ParallelFor.WithConfiguration(
-                        minY,
-                        maxY,
-                        configuration,
-                        y =>
-                            {
-                                int offsetY = y - startY;
-                                int offsetX = minX - startX;
-
-                                applicator.Apply(amount.GetSpan(), offsetX, offsetY);
-                            });
-                }
-            }
-        }
-
-        private bool IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush)
-        {
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers;
+using System.Threading.Tasks;
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Memory;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors.Drawing
+{
+    /// <summary>
+    /// Using the brush as a source of pixels colors blends the brush color with source.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    internal class FillProcessor<TPixel> : ImageProcessor<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <summary>
+        /// The brush.
+        /// </summary>
+        private readonly IBrush<TPixel> brush;
+        private readonly GraphicsOptions options;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FillProcessor{TPixel}"/> class.
+        /// </summary>
+        /// <param name="brush">The brush to source pixel colors from.</param>
+        /// <param name="options">The options</param>
+        public FillProcessor(IBrush<TPixel> brush, GraphicsOptions options)
+        {
+            this.brush = brush;
+            this.options = options;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
+        {
+            int startX = sourceRectangle.X;
+            int endX = sourceRectangle.Right;
+            int startY = sourceRectangle.Y;
+            int endY = sourceRectangle.Bottom;
+
+            // Align start/end positions.
+            int minX = Math.Max(0, startX);
+            int maxX = Math.Min(source.Width, endX);
+            int minY = Math.Max(0, startY);
+            int maxY = Math.Min(source.Height, endY);
+
+            int width = maxX - minX;
+
+            var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
+            // If there's no reason for blending, then avoid it.
+            if (this.IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush))
+            {
+                ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings().MultiplyMinimumPixelsPerTask(4);
+
+                ParallelHelper.IterateRows(
+                    workingRect,
+                    parallelSettings,
+                    rows =>
+                        {
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                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 (IMemoryOwner<float> amount = source.MemoryAllocator.Allocate<float>(width))
+                using (BrushApplicator<TPixel> applicator = this.brush.CreateApplicator(
+                    source,
+                    sourceRectangle,
+                    this.options))
+                {
+                    amount.GetSpan().Fill(1f);
+
+                    ParallelHelper.IterateRows(
+                        workingRect,
+                        configuration,
+                        rows =>
+                            {
+                                for (int y = rows.Min; y < rows.Max; y++)
+                                {
+                                    int offsetY = y - startY;
+                                    int offsetX = minX - startX;
+
+                                    applicator.Apply(amount.GetSpan(), offsetX, offsetY);
+                                }
+                            });
+                }
+            }
+        }
+
+        private bool IsSolidBrushWithoutBlending(out SolidBrush<TPixel> solidBrush)
+        {
             solidBrush = this.brush as SolidBrush<TPixel>;
 
             if (solidBrush == null)
@@ -109,7 +118,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Drawing
                 return false;
             }
 
-            return this.options.IsOpaqueColorWithoutBlending(solidBrush.Color);
-        }
-    }
+            return this.options.IsOpaqueColorWithoutBlending(solidBrush.Color);
+        }
+    }
 }

src/ImageSharp/Common/Extensions/EncoderExtensions.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+#if !NETCOREAPP2_1
+using System;
+using System.Text;
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Extension methods for the <see cref="Encoder"/> type.
+    /// </summary>
+    internal static unsafe class EncoderExtensions
+    {
+        /// <summary>
+        /// Gets a string from the provided buffer data.
+        /// </summary>
+        /// <param name="encoding">The encoding.</param>
+        /// <param name="buffer">The buffer.</param>
+        /// <returns>The string.</returns>
+        public static string GetString(this Encoding encoding, ReadOnlySpan<byte> buffer)
+        {
+#if NETSTANDARD1_1
+            return encoding.GetString(buffer.ToArray());
+#else
+            fixed (byte* bytes = buffer)
+            {
+                return encoding.GetString(bytes, buffer.Length);
+            }
+#endif
+        }
+    }
+}
+#endif

src/ImageSharp/Common/Helpers/ParallelFor.cs

@@ -1,61 +0,0 @@
-using System;
-using System.Buffers;
-using System.Threading.Tasks;
-using SixLabors.Memory;
-
-namespace SixLabors.ImageSharp
-{
-    /// <summary>
-    /// Utility methods for Parallel.For() execution. Use this instead of raw <see cref="Parallel"/> calls!
-    /// </summary>
-    internal static class ParallelFor
-    {
-        /// <summary>
-        /// Helper method to execute Parallel.For using the settings in <paramref name="configuration"/>
-        /// </summary>
-        public static void WithConfiguration(int fromInclusive, int toExclusive, Configuration configuration, Action<int> body)
-        {
-            Parallel.For(fromInclusive, toExclusive, configuration.GetParallelOptions(), body);
-        }
-
-        /// <summary>
-        /// Helper method to execute Parallel.For with temporary worker buffer shared between executing tasks.
-        /// The buffer is not guaranteed to be clean!
-        /// </summary>
-        /// <typeparam name="T">The value type of the buffer</typeparam>
-        /// <param name="fromInclusive">The start index, inclusive.</param>
-        /// <param name="toExclusive">The end index, exclusive.</param>
-        /// <param name="configuration">The <see cref="Configuration"/> used for getting the <see cref="MemoryAllocator"/> and <see cref="ParallelOptions"/></param>
-        /// <param name="bufferLength">The length of the requested parallel buffer</param>
-        /// <param name="body">The delegate that is invoked once per iteration.</param>
-        public static void WithTemporaryBuffer<T>(
-            int fromInclusive,
-            int toExclusive,
-            Configuration configuration,
-            int bufferLength,
-            Action<int, IMemoryOwner<T>> body)
-            where T : struct
-        {
-            MemoryAllocator memoryAllocator = configuration.MemoryAllocator;
-            ParallelOptions parallelOptions = configuration.GetParallelOptions();
-
-            IMemoryOwner<T> InitBuffer()
-            {
-                return memoryAllocator.Allocate<T>(bufferLength);
-            }
-
-            void CleanUpBuffer(IMemoryOwner<T> buffer)
-            {
-                buffer.Dispose();
-            }
-
-            IMemoryOwner<T> BodyFunc(int i, ParallelLoopState state, IMemoryOwner<T> buffer)
-            {
-                body(i, buffer);
-                return buffer;
-            }
-
-            Parallel.For(fromInclusive, toExclusive, parallelOptions, InitBuffer, BodyFunc, CleanUpBuffer);
-        }
-    }
-}

src/ImageSharp/Common/ParallelUtils/ParallelExecutionSettings.cs

@@ -0,0 +1,71 @@
+// Copyright(c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Threading.Tasks;
+
+using SixLabors.Memory;
+
+namespace SixLabors.ImageSharp.ParallelUtils
+{
+    /// <summary>
+    /// Defines execution settings for methods in <see cref="ParallelHelper"/>.
+    /// </summary>
+    internal readonly struct ParallelExecutionSettings
+    {
+        /// <summary>
+        /// Default value for <see cref="MinimumPixelsProcessedPerTask"/>.
+        /// </summary>
+        public const int DefaultMinimumPixelsProcessedPerTask = 4096;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ParallelExecutionSettings"/> struct.
+        /// </summary>
+        public ParallelExecutionSettings(
+            int maxDegreeOfParallelism,
+            int minimumPixelsProcessedPerTask,
+            MemoryAllocator memoryAllocator)
+        {
+            this.MaxDegreeOfParallelism = maxDegreeOfParallelism;
+            this.MinimumPixelsProcessedPerTask = minimumPixelsProcessedPerTask;
+            this.MemoryAllocator = memoryAllocator;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ParallelExecutionSettings"/> struct.
+        /// </summary>
+        public ParallelExecutionSettings(int maxDegreeOfParallelism, MemoryAllocator memoryAllocator)
+            : this(maxDegreeOfParallelism, DefaultMinimumPixelsProcessedPerTask, memoryAllocator)
+        {
+        }
+
+        /// <summary>
+        /// Gets the MemoryAllocator
+        /// </summary>
+        public MemoryAllocator MemoryAllocator { get; }
+
+        /// <summary>
+        /// Gets the value used for initializing <see cref="ParallelOptions.MaxDegreeOfParallelism"/> when using TPL.
+        /// </summary>
+        public int MaxDegreeOfParallelism { get; }
+
+        /// <summary>
+        /// Gets the minimum number of pixels being processed by a single task when parallelizing operations with TPL.
+        /// Launching tasks for pixel regions below this limit is not worth the overhead.
+        /// Initialized with <see cref="DefaultMinimumPixelsProcessedPerTask"/> by default,
+        /// the optimum value is operation specific. (The cheaper the operation, the larger the value is.)
+        /// </summary>
+        public int MinimumPixelsProcessedPerTask { get; }
+
+        /// <summary>
+        /// Creates a new instance of <see cref="ParallelExecutionSettings"/>
+        /// having <see cref="MinimumPixelsProcessedPerTask"/> multiplied by <paramref name="multiplier"/>
+        /// </summary>
+        public ParallelExecutionSettings MultiplyMinimumPixelsPerTask(int multiplier)
+        {
+            return new ParallelExecutionSettings(
+                this.MaxDegreeOfParallelism,
+                this.MinimumPixelsProcessedPerTask * multiplier,
+                this.MemoryAllocator);
+        }
+    }
+}

src/ImageSharp/Common/ParallelUtils/ParallelHelper.cs

@@ -0,0 +1,146 @@
+// 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.Threading.Tasks;
+
+using SixLabors.ImageSharp.Memory;
+using SixLabors.Memory;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.ParallelUtils
+{
+    /// <summary>
+    /// Utility methods for batched processing of pixel row intervals.
+    /// Parallel execution is optimized for image processing.
+    /// Use this instead of direct <see cref="Parallel"/> calls!
+    /// </summary>
+    internal static class ParallelHelper
+    {
+        /// <summary>
+        /// Get the default <see cref="ParallelExecutionSettings"/> for a <see cref="Configuration"/>
+        /// </summary>
+        public static ParallelExecutionSettings GetParallelSettings(this Configuration configuration)
+        {
+            return new ParallelExecutionSettings(configuration.MaxDegreeOfParallelism, configuration.MemoryAllocator);
+        }
+
+        /// <summary>
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s.
+        /// </summary>
+        public static void IterateRows(Rectangle rectangle, Configuration configuration, Action<RowInterval> body)
+        {
+            ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings();
+
+            IterateRows(rectangle, parallelSettings, body);
+        }
+
+        /// <summary>
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s.
+        /// </summary>
+        public static void IterateRows(
+            Rectangle rectangle,
+            in ParallelExecutionSettings parallelSettings,
+            Action<RowInterval> body)
+        {
+            DebugGuard.MustBeGreaterThan(rectangle.Width, 0, nameof(rectangle));
+
+            int maxSteps = DivideCeil(rectangle.Width * rectangle.Height, parallelSettings.MinimumPixelsProcessedPerTask);
+
+            int numOfSteps = Math.Min(parallelSettings.MaxDegreeOfParallelism, maxSteps);
+
+            // Avoid TPL overhead in this trivial case:
+            if (numOfSteps == 1)
+            {
+                var rows = new RowInterval(rectangle.Top, rectangle.Bottom);
+                body(rows);
+                return;
+            }
+
+            int verticalStep = DivideCeil(rectangle.Height, numOfSteps);
+
+            var parallelOptions = new ParallelOptions() { MaxDegreeOfParallelism = numOfSteps };
+
+            Parallel.For(
+                0,
+                numOfSteps,
+                parallelOptions,
+                i =>
+                    {
+                        int yMin = rectangle.Top + (i * verticalStep);
+                        int yMax = Math.Min(yMin + verticalStep, rectangle.Bottom);
+
+                        var rows = new RowInterval(yMin, yMax);
+                        body(rows);
+                    });
+        }
+
+        /// <summary>
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s
+        /// instantiating a temporary buffer for each <paramref name="body"/> invocation.
+        /// </summary>
+        public static void IterateRowsWithTempBuffer<T>(
+            Rectangle rectangle,
+            in ParallelExecutionSettings parallelSettings,
+            Action<RowInterval, Memory<T>> body)
+            where T : struct
+        {
+            int maxSteps = DivideCeil(rectangle.Width * rectangle.Height, parallelSettings.MinimumPixelsProcessedPerTask);
+
+            int numOfSteps = Math.Min(parallelSettings.MaxDegreeOfParallelism, maxSteps);
+
+            MemoryAllocator memoryAllocator = parallelSettings.MemoryAllocator;
+
+            // Avoid TPL overhead in this trivial case:
+            if (numOfSteps == 1)
+            {
+                var rows = new RowInterval(rectangle.Top, rectangle.Bottom);
+                using (IMemoryOwner<T> buffer = memoryAllocator.Allocate<T>(rectangle.Width))
+                {
+                    body(rows, buffer.Memory);
+                }
+
+                return;
+            }
+
+            int verticalStep = DivideCeil(rectangle.Height, numOfSteps);
+
+            var parallelOptions = new ParallelOptions() { MaxDegreeOfParallelism = numOfSteps };
+
+            Parallel.For(
+                0,
+                numOfSteps,
+                parallelOptions,
+                i =>
+                    {
+                        int yMin = rectangle.Top + (i * verticalStep);
+                        int yMax = Math.Min(yMin + verticalStep, rectangle.Bottom);
+
+                        var rows = new RowInterval(yMin, yMax);
+
+                        using (IMemoryOwner<T> buffer = memoryAllocator.Allocate<T>(rectangle.Width))
+                        {
+                            body(rows, buffer.Memory);
+                        }
+                    });
+        }
+
+        /// <summary>
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s
+        /// instantiating a temporary buffer for each <paramref name="body"/> invocation.
+        /// </summary>
+        public static void IterateRowsWithTempBuffer<T>(
+            Rectangle rectangle,
+            Configuration configuration,
+            Action<RowInterval, Memory<T>> body)
+            where T : struct
+        {
+            IterateRowsWithTempBuffer(rectangle, configuration.GetParallelSettings(), body);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static int DivideCeil(int dividend, int divisor) => 1 + ((dividend - 1) / divisor);
+    }
+}

src/ImageSharp/Configuration.cs

@@ -59,6 +59,7 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Gets or sets the maximum number of concurrent tasks enabled in ImageSharp algorithms
         /// configured with this <see cref="Configuration"/> instance.
+        /// Initialized with <see cref="Environment.ProcessorCount"/> by default.
         /// </summary>
         public int MaxDegreeOfParallelism
         {
@@ -125,7 +126,7 @@ namespace SixLabors.ImageSharp
         /// Creates a shallow copy of the <see cref="Configuration"/>
         /// </summary>
         /// <returns>A new configuration instance</returns>
-        public Configuration ShallowCopy()
+        public Configuration Clone()
         {
             return new Configuration
             {

src/ImageSharp/Formats/Bmp/BmpMetaData.cs

@@ -6,13 +6,29 @@ namespace SixLabors.ImageSharp.Formats.Bmp
     /// <summary>
     /// Provides Bmp specific metadata information for the image.
     /// </summary>
-    public class BmpMetaData
+    public class BmpMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BmpMetaData"/> class.
+        /// </summary>
+        public BmpMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BmpMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        private BmpMetaData(BmpMetaData other) => this.BitsPerPixel = other.BitsPerPixel;
+
         /// <summary>
         /// Gets or sets the number of bits per pixel.
         /// </summary>
         public BmpBitsPerPixel BitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel24;
 
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new BmpMetaData(this);
+
         // TODO: Colors used once we support encoding palette bmps.
     }
-}
+}

src/ImageSharp/Formats/Gif/GifFrameMetaData.cs

@@ -6,8 +6,26 @@ namespace SixLabors.ImageSharp.Formats.Gif
     /// <summary>
     /// Provides Gif specific metadata information for the image frame.
     /// </summary>
-    public class GifFrameMetaData
+    public class GifFrameMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifFrameMetaData"/> class.
+        /// </summary>
+        public GifFrameMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifFrameMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        private GifFrameMetaData(GifFrameMetaData other)
+        {
+            this.ColorTableLength = other.ColorTableLength;
+            this.FrameDelay = other.FrameDelay;
+            this.DisposalMethod = other.DisposalMethod;
+        }
+
         /// <summary>
         /// Gets or sets the length of the color table for paletted images.
         /// If not 0, then this field indicates the maximum number of colors to use when quantizing the
@@ -29,5 +47,8 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// be treated after being displayed.
         /// </summary>
         public GifDisposalMethod DisposalMethod { get; set; }
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new GifFrameMetaData(this);
     }
 }

src/ImageSharp/Formats/Gif/GifMetaData.cs

@@ -6,8 +6,26 @@ namespace SixLabors.ImageSharp.Formats.Gif
     /// <summary>
     /// Provides Gif specific metadata information for the image.
     /// </summary>
-    public class GifMetaData
+    public class GifMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifMetaData"/> class.
+        /// </summary>
+        public GifMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        private GifMetaData(GifMetaData other)
+        {
+            this.RepeatCount = other.RepeatCount;
+            this.ColorTableMode = other.ColorTableMode;
+            this.GlobalColorTableLength = other.GlobalColorTableLength;
+        }
+
         /// <summary>
         /// Gets or sets the number of times any animation is repeated.
         /// <remarks>
@@ -25,5 +43,8 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// Gets or sets the length of the global color table if present.
         /// </summary>
         public int GlobalColorTableLength { get; set; }
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new GifMetaData(this);
     }
 }

src/ImageSharp/Formats/Jpeg/JpegMetaData.cs

@@ -6,11 +6,27 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
     /// <summary>
     /// Provides Jpeg specific metadata information for the image.
     /// </summary>
-    public class JpegMetaData
+    public class JpegMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="JpegMetaData"/> class.
+        /// </summary>
+        public JpegMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="JpegMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        private JpegMetaData(JpegMetaData other) => this.Quality = other.Quality;
+
         /// <summary>
         /// Gets or sets the encoded quality.
         /// </summary>
         public int Quality { get; set; } = 75;
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new JpegMetaData(this);
     }
 }

src/ImageSharp/Formats/Png/Adam7.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace SixLabors.ImageSharp.Formats.Png
+{
+    /// <summary>
+    /// Constants and helper methods for the Adam7 interlacing algorithm.
+    /// </summary>
+    internal static class Adam7
+    {
+        /// <summary>
+        /// The amount to increment when processing each column per scanline for each interlaced pass.
+        /// </summary>
+        public static readonly int[] ColumnIncrement = { 8, 8, 4, 4, 2, 2, 1 };
+
+        /// <summary>
+        /// The index to start at when processing each column per scanline for each interlaced pass.
+        /// </summary>
+        public static readonly int[] FirstColumn = { 0, 4, 0, 2, 0, 1, 0 };
+
+        /// <summary>
+        /// The index to start at when processing each row per scanline for each interlaced pass.
+        /// </summary>
+        public static readonly int[] FirstRow = { 0, 0, 4, 0, 2, 0, 1 };
+
+        /// <summary>
+        /// The amount to increment when processing each row per scanline for each interlaced pass.
+        /// </summary>
+        public static readonly int[] RowIncrement = { 8, 8, 8, 4, 4, 2, 2 };
+
+        /// <summary>
+        /// Returns the correct number of columns for each interlaced pass.
+        /// </summary>
+        /// <param name="width">The line width.</param>
+        /// <param name="passIndex">The current pass index.</param>
+        /// <returns>The <see cref="int"/></returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int ComputeColumns(int width, int passIndex)
+        {
+            switch (passIndex)
+            {
+                case 0: return (width + 7) / 8;
+                case 1: return (width + 3) / 8;
+                case 2: return (width + 3) / 4;
+                case 3: return (width + 1) / 4;
+                case 4: return (width + 1) / 2;
+                case 5: return width / 2;
+                case 6: return width;
+                default: throw new ArgumentException($"Not a valid pass index: {passIndex}");
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Png/Chunks/PhysicalChunkData.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Buffers.Binary;
+using SixLabors.ImageSharp.Common.Helpers;
+using SixLabors.ImageSharp.MetaData;
+
+namespace SixLabors.ImageSharp.Formats.Png.Chunks
+{
+    /// <summary>
+    /// The pHYs chunk specifies the intended pixel size or aspect ratio for display of the image.
+    /// </summary>
+    internal readonly struct PhysicalChunkData
+    {
+        public const int Size = 9;
+
+        public PhysicalChunkData(uint x, uint y, byte unitSpecifier)
+        {
+            this.XAxisPixelsPerUnit = x;
+            this.YAxisPixelsPerUnit = y;
+            this.UnitSpecifier = unitSpecifier;
+        }
+
+        /// <summary>
+        /// Gets the number of pixels per unit on the X axis.
+        /// </summary>
+        public uint XAxisPixelsPerUnit { get; }
+
+        /// <summary>
+        /// Gets the number of pixels per unit on the Y axis.
+        /// </summary>
+        public uint YAxisPixelsPerUnit { get; }
+
+        /// <summary>
+        /// Gets the unit specifier.
+        /// 0: unit is unknown
+        /// 1: unit is the meter
+        /// When the unit specifier is 0, the pHYs chunk defines pixel aspect ratio only; the actual size of the pixels remains unspecified.
+        /// </summary>
+        public byte UnitSpecifier { get; }
+
+        /// <summary>
+        /// Parses the PhysicalChunkData from the given buffer.
+        /// </summary>
+        /// <param name="data">The data buffer.</param>
+        /// <returns>The parsed PhysicalChunkData.</returns>
+        public static PhysicalChunkData Parse(ReadOnlySpan<byte> data)
+        {
+            uint hResolution = BinaryPrimitives.ReadUInt32BigEndian(data.Slice(0, 4));
+            uint vResolution = BinaryPrimitives.ReadUInt32BigEndian(data.Slice(4, 4));
+            byte unit = data[8];
+
+            return new PhysicalChunkData(hResolution, vResolution, unit);
+        }
+
+        /// <summary>
+        /// Constructs the PngPhysicalChunkData from the provided metadata.
+        /// If the resolution units are not in meters, they are automatically convereted.
+        /// </summary>
+        /// <param name="meta">The metadata.</param>
+        /// <returns>The constructed PngPhysicalChunkData instance.</returns>
+        public static PhysicalChunkData FromMetadata(ImageMetaData meta)
+        {
+            byte unitSpecifier = 0;
+            uint x;
+            uint y;
+
+            switch (meta.ResolutionUnits)
+            {
+                case PixelResolutionUnit.AspectRatio:
+                    unitSpecifier = 0; // Unspecified
+                    x = (uint)Math.Round(meta.HorizontalResolution);
+                    y = (uint)Math.Round(meta.VerticalResolution);
+                    break;
+
+                case PixelResolutionUnit.PixelsPerInch:
+                    unitSpecifier = 1; // Per meter
+                    x = (uint)Math.Round(UnitConverter.InchToMeter(meta.HorizontalResolution));
+                    y = (uint)Math.Round(UnitConverter.InchToMeter(meta.VerticalResolution));
+                    break;
+
+                case PixelResolutionUnit.PixelsPerCentimeter:
+                    unitSpecifier = 1; // Per meter
+                    x = (uint)Math.Round(UnitConverter.CmToMeter(meta.HorizontalResolution));
+                    y = (uint)Math.Round(UnitConverter.CmToMeter(meta.VerticalResolution));
+                    break;
+
+                default:
+                    unitSpecifier = 1; // Per meter
+                    x = (uint)Math.Round(meta.HorizontalResolution);
+                    y = (uint)Math.Round(meta.VerticalResolution);
+                    break;
+            }
+
+            return new PhysicalChunkData(x, y, unitSpecifier);
+        }
+
+        /// <summary>
+        /// Writes the data to the given buffer.
+        /// </summary>
+        /// <param name="buffer">The buffer.</param>
+        public void WriteTo(Span<byte> buffer)
+        {
+            BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(0, 4), this.XAxisPixelsPerUnit);
+            BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(4, 4), this.YAxisPixelsPerUnit);
+            buffer[8] = this.UnitSpecifier;
+        }
+    }
+}

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

@@ -30,7 +30,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
 
             // Average(x) + floor((Raw(x-bpp)+Prior(x))/2)
             int x = 1;
-            for (; x <= bytesPerPixel /* Note the <= because x starts at 1 */; ++x) {
+            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));
@@ -68,7 +69,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             resultBaseRef = 3;
 
             int x = 0;
-            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+            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;
@@ -77,7 +79,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
                 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 */) {
+            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);
@@ -97,9 +100,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
         /// <param name="above">The above byte</param>
         /// <returns>The <see cref="int"/></returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static int Average(byte left, byte above)
-        {
-            return (left + above) >> 1;
-        }
+        private static int Average(byte left, byte above) => (left + above) >> 1;
     }
 }

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

@@ -72,7 +72,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             resultBaseRef = 4;
 
             int x = 0;
-            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+            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;
@@ -81,7 +82,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
                 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 */) {
+            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);

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

@@ -59,7 +59,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
             resultBaseRef = 1;
 
             int x = 0;
-            for (; x < bytesPerPixel; /* Note: ++x happens in the body to avoid one add operation */) {
+            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);
@@ -67,7 +68,8 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters
                 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 */) {
+            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;

src/ImageSharp/Formats/Png/IPngEncoderOptions.cs

@@ -24,7 +24,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <summary>
         /// Gets the filter method.
         /// </summary>
-        PngFilterMethod FilterMethod { get; }
+        PngFilterMethod? FilterMethod { get; }
 
         /// <summary>
         /// Gets the compression level 1-9.

src/ImageSharp/Formats/Png/PngBitDepth.cs

@@ -7,7 +7,7 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// <summary>
     /// Provides enumeration for the available PNG bit depths.
     /// </summary>
-    public enum PngBitDepth
+    public enum PngBitDepth : byte
     {
         /// <summary>
         /// 1 bit per sample or per palette index (not per pixel).

src/ImageSharp/Formats/Png/PngConstants.cs

@@ -41,5 +41,17 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// The header bytes as a big endian coded ulong.
         /// </summary>
         public const ulong HeaderValue = 0x89504E470D0A1A0AUL;
+
+        /// <summary>
+        /// The dictionary of available color types.
+        /// </summary>
+        public static readonly Dictionary<PngColorType, byte[]> ColorTypes = new Dictionary<PngColorType, byte[]>()
+        {
+            [PngColorType.Grayscale] = new byte[] { 1, 2, 4, 8, 16 },
+            [PngColorType.Rgb] = new byte[] { 8, 16 },
+            [PngColorType.Palette] = new byte[] { 1, 2, 4, 8 },
+            [PngColorType.GrayscaleWithAlpha] = new byte[] { 8, 16 },
+            [PngColorType.RgbWithAlpha] = new byte[] { 8, 16 }
+        };
     }
 }

src/ImageSharp/Formats/Png/PngEncoder.cs

@@ -27,7 +27,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <summary>
         /// Gets or sets the filter method.
         /// </summary>
-        public PngFilterMethod FilterMethod { get; set; } = PngFilterMethod.Paeth;
+        public PngFilterMethod? FilterMethod { get; set; }
 
         /// <summary>
         /// Gets or sets the compression level 1-9.

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -3,9 +3,13 @@
 
 using System;
 using System.Buffers.Binary;
+using System.Collections.Generic;
 using System.IO;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Common.Helpers;
+using SixLabors.ImageSharp.Formats.Png.Chunks;
 using SixLabors.ImageSharp.Formats.Png.Filters;
 using SixLabors.ImageSharp.Formats.Png.Zlib;
 using SixLabors.ImageSharp.Memory;
@@ -21,6 +25,21 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// </summary>
     internal sealed class PngEncoderCore : IDisposable
     {
+        /// <summary>
+        /// The dictionary of available color types.
+        /// </summary>
+        private static readonly Dictionary<PngColorType, byte[]> ColorTypes = new Dictionary<PngColorType, byte[]>()
+        {
+            [PngColorType.Grayscale] = new byte[] { 1, 2, 4, 8, 16 },
+            [PngColorType.Rgb] = new byte[] { 8, 16 },
+            [PngColorType.Palette] = new byte[] { 1, 2, 4, 8 },
+            [PngColorType.GrayscaleWithAlpha] = new byte[] { 8, 16 },
+            [PngColorType.RgbWithAlpha] = new byte[] { 8, 16 }
+        };
+
+        /// <summary>
+        /// Used the manage memory allocations.
+        /// </summary>
         private readonly MemoryAllocator memoryAllocator;
 
         /// <summary>
@@ -158,7 +177,11 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.memoryAllocator = memoryAllocator;
             this.pngBitDepth = options.BitDepth;
             this.pngColorType = options.ColorType;
-            this.pngFilterMethod = options.FilterMethod;
+
+            // Specification recommends default filter method None for paletted images and Paeth for others.
+            this.pngFilterMethod = options.FilterMethod ?? (options.ColorType.Equals(PngColorType.Palette)
+                ? PngFilterMethod.None
+                : PngFilterMethod.Paeth);
             this.compressionLevel = options.CompressionLevel;
             this.gamma = options.Gamma;
             this.quantizer = options.Quantizer;
@@ -189,28 +212,37 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.pngBitDepth = this.pngBitDepth ?? pngMetaData.BitDepth;
             this.use16Bit = this.pngBitDepth.Equals(PngBitDepth.Bit16);
 
+            // Ensure we are not allowing impossible combinations.
+            if (!ColorTypes.ContainsKey(this.pngColorType.Value))
+            {
+                throw new NotSupportedException("Color type is not supported or not valid.");
+            }
+
             stream.Write(PngConstants.HeaderBytes, 0, PngConstants.HeaderBytes.Length);
 
             QuantizedFrame<TPixel> quantized = null;
-            ReadOnlySpan<byte> quantizedPixelsSpan = default;
             if (this.pngColorType == PngColorType.Palette)
             {
-                byte bits;
+                byte bits = (byte)this.pngBitDepth;
+                if (!ColorTypes[this.pngColorType.Value].Contains(bits))
+                {
+                    throw new NotSupportedException("Bit depth is not supported or not valid.");
+                }
 
                 // Use the metadata to determine what quantization depth to use if no quantizer has been set.
                 if (this.quantizer == null)
                 {
-                    bits = (byte)Math.Min(8u, (short)this.pngBitDepth);
-                    int colorSize = ImageMaths.GetColorCountForBitDepth(bits);
-                    this.quantizer = new WuQuantizer(colorSize);
+                    this.quantizer = new WuQuantizer(ImageMaths.GetColorCountForBitDepth(bits));
                 }
 
                 // Create quantized frame returning the palette and set the bit depth.
                 quantized = this.quantizer.CreateFrameQuantizer<TPixel>().QuantizeFrame(image.Frames.RootFrame);
-                quantizedPixelsSpan = quantized.GetPixelSpan();
-                bits = (byte)ImageMaths.GetBitsNeededForColorDepth(quantized.Palette.Length).Clamp(1, 8);
+                byte quantizedBits = (byte)ImageMaths.GetBitsNeededForColorDepth(quantized.Palette.Length).Clamp(1, 8);
+                bits = Math.Max(bits, quantizedBits);
 
                 // Png only supports in four pixel depths: 1, 2, 4, and 8 bits when using the PLTE chunk
+                // We check again for the bit depth as the bit depth of the color palette from a given quantizer might not
+                // be within the acceptable range.
                 if (bits == 3)
                 {
                     bits = 4;
@@ -224,7 +256,11 @@ namespace SixLabors.ImageSharp.Formats.Png
             }
             else
             {
-                this.bitDepth = (byte)(this.use16Bit ? 16 : 8);
+                this.bitDepth = (byte)this.pngBitDepth;
+                if (!ColorTypes[this.pngColorType.Value].Contains(this.bitDepth))
+                {
+                    throw new NotSupportedException("Bit depth is not supported or not valid.");
+                }
             }
 
             this.bytesPerPixel = this.CalculateBytesPerPixel();
@@ -249,7 +285,7 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.WritePhysicalChunk(stream, metaData);
             this.WriteGammaChunk(stream);
             this.WriteExifChunk(stream, metaData);
-            this.WriteDataChunks(image.Frames.RootFrame, quantizedPixelsSpan, stream);
+            this.WriteDataChunks(image.Frames.RootFrame, quantized, stream);
             this.WriteEndChunk(stream);
             stream.Flush();
 
@@ -280,32 +316,55 @@ namespace SixLabors.ImageSharp.Formats.Png
             const float RX = .2126F;
             const float GX = .7152F;
             const float BX = .0722F;
+
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
             Span<byte> rawScanlineSpan = this.rawScanline.GetSpan();
+            ref byte rawScanlineSpanRef = ref MemoryMarshal.GetReference(rawScanlineSpan);
 
             if (this.pngColorType.Equals(PngColorType.Grayscale))
             {
-                // TODO: Realistically we should support 1, 2, 4, 8, and 16 bit grayscale images.
-                // we currently do the other types via palette. Maybe RC as I don't understand how the data is packed yet
-                // for 1, 2, and 4 bit grayscale images.
+                // TODO: Research and add support for grayscale plus tRNS
                 if (this.use16Bit)
                 {
                     // 16 bit grayscale
                     Rgb48 rgb = default;
                     for (int x = 0, o = 0; x < rowSpan.Length; x++, o += 2)
                     {
-                        rowSpan[x].ToRgb48(ref rgb);
+                        Unsafe.Add(ref rowSpanRef, x).ToRgb48(ref rgb);
                         ushort luminance = (ushort)((RX * rgb.R) + (GX * rgb.G) + (BX * rgb.B));
                         BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o, 2), luminance);
                     }
                 }
                 else
                 {
-                    // 8 bit grayscale
-                    Rgb24 rgb = default;
-                    for (int x = 0; x < rowSpan.Length; x++)
+                    if (this.bitDepth == 8)
+                    {
+                        // 8 bit grayscale
+                        Rgb24 rgb = default;
+                        for (int x = 0; x < rowSpan.Length; x++)
+                        {
+                            Unsafe.Add(ref rowSpanRef, x).ToRgb24(ref rgb);
+                            Unsafe.Add(ref rawScanlineSpanRef, x) = (byte)((RX * rgb.R) + (GX * rgb.G) + (BX * rgb.B));
+                        }
+                    }
+                    else
                     {
-                        rowSpan[x].ToRgb24(ref rgb);
-                        rawScanlineSpan[x] = (byte)((RX * rgb.R) + (GX * rgb.G) + (BX * rgb.B));
+                        // 1, 2, and 4 bit grayscale
+                        using (IManagedByteBuffer temp = this.memoryAllocator.AllocateManagedByteBuffer(rowSpan.Length, AllocationOptions.Clean))
+                        {
+                            int scaleFactor = 255 / (ImageMaths.GetColorCountForBitDepth(this.bitDepth) - 1);
+                            Span<byte> tempSpan = temp.GetSpan();
+                            ref byte tempSpanRef = ref MemoryMarshal.GetReference(tempSpan);
+
+                            Rgb24 rgb = default;
+                            for (int x = 0; x < rowSpan.Length; x++)
+                            {
+                                Unsafe.Add(ref rowSpanRef, x).ToRgb24(ref rgb);
+                                float luminance = ((RX * rgb.R) + (GX * rgb.G) + (BX * rgb.B)) / scaleFactor;
+                                Unsafe.Add(ref tempSpanRef, x) = (byte)luminance;
+                                this.ScaleDownFrom8BitArray(tempSpan, rawScanlineSpan, this.bitDepth);
+                            }
+                        }
                     }
                 }
             }
@@ -317,7 +376,7 @@ namespace SixLabors.ImageSharp.Formats.Png
                     Rgba64 rgba = default;
                     for (int x = 0, o = 0; x < rowSpan.Length; x++, o += 4)
                     {
-                        rowSpan[x].ToRgba64(ref rgba);
+                        Unsafe.Add(ref rowSpanRef, x).ToRgba64(ref rgba);
                         ushort luminance = (ushort)((RX * rgba.R) + (GX * rgba.G) + (BX * rgba.B));
                         BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o, 2), luminance);
                         BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o + 2, 2), rgba.A);
@@ -329,9 +388,9 @@ namespace SixLabors.ImageSharp.Formats.Png
                     Rgba32 rgba = default;
                     for (int x = 0, o = 0; x < rowSpan.Length; x++, o += 2)
                     {
-                        rowSpan[x].ToRgba32(ref rgba);
-                        rawScanlineSpan[o] = (byte)((RX * rgba.R) + (GX * rgba.G) + (BX * rgba.B));
-                        rawScanlineSpan[o + 1] = rgba.A;
+                        Unsafe.Add(ref rowSpanRef, x).ToRgba32(ref rgba);
+                        Unsafe.Add(ref rawScanlineSpanRef, o) = (byte)((RX * rgba.R) + (GX * rgba.G) + (BX * rgba.B));
+                        Unsafe.Add(ref rawScanlineSpanRef, o + 1) = rgba.A;
                     }
                 }
             }
@@ -367,9 +426,10 @@ namespace SixLabors.ImageSharp.Formats.Png
                     {
                         // 16 bit Rgba
                         Rgba64 rgba = default;
+                        ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
                         for (int x = 0, o = 0; x < rowSpan.Length; x++, o += 8)
                         {
-                            rowSpan[x].ToRgba64(ref rgba);
+                            Unsafe.Add(ref rowSpanRef, x).ToRgba64(ref rgba);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o, 2), rgba.R);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o + 2, 2), rgba.G);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o + 4, 2), rgba.B);
@@ -383,9 +443,10 @@ namespace SixLabors.ImageSharp.Formats.Png
                     {
                         // 16 bit Rgb
                         Rgb48 rgb = default;
+                        ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
                         for (int x = 0, o = 0; x < rowSpan.Length; x++, o += 6)
                         {
-                            rowSpan[x].ToRgb48(ref rgb);
+                            Unsafe.Add(ref rowSpanRef, x).ToRgb48(ref rgb);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o, 2), rgb.R);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o + 2, 2), rgb.G);
                             BinaryPrimitives.WriteUInt16BigEndian(rawScanlineSpan.Slice(o + 4, 2), rgb.B);
@@ -402,18 +463,25 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="rowSpan">The row span.</param>
-        /// <param name="quantizedPixelsSpan">The span of quantized pixels. Can be null.</param>
+        /// <param name="quantized">The quantized pixels. Can be null.</param>
         /// <param name="row">The row.</param>
         /// <returns>The <see cref="IManagedByteBuffer"/></returns>
-        private IManagedByteBuffer EncodePixelRow<TPixel>(ReadOnlySpan<TPixel> rowSpan, ReadOnlySpan<byte> quantizedPixelsSpan, int row)
+        private IManagedByteBuffer EncodePixelRow<TPixel>(ReadOnlySpan<TPixel> rowSpan, QuantizedFrame<TPixel> quantized, int row)
             where TPixel : struct, IPixel<TPixel>
         {
             switch (this.pngColorType)
             {
                 case PngColorType.Palette:
 
-                    int stride = this.rawScanline.Length();
-                    quantizedPixelsSpan.Slice(row * stride, stride).CopyTo(this.rawScanline.GetSpan());
+                    if (this.bitDepth < 8)
+                    {
+                        this.ScaleDownFrom8BitArray(quantized.GetRowSpan(row), this.rawScanline.GetSpan(), this.bitDepth);
+                    }
+                    else
+                    {
+                        int stride = this.rawScanline.Length();
+                        quantized.GetPixelSpan().Slice(row * stride, stride).CopyTo(this.rawScanline.GetSpan());
+                    }
 
                     break;
                 case PngColorType.Grayscale:
@@ -538,16 +606,9 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <param name="header">The <see cref="PngHeader"/>.</param>
         private void WriteHeaderChunk(Stream stream, in PngHeader header)
         {
-            BinaryPrimitives.WriteInt32BigEndian(this.chunkDataBuffer.AsSpan(0, 4), header.Width);
-            BinaryPrimitives.WriteInt32BigEndian(this.chunkDataBuffer.AsSpan(4, 4), header.Height);
-
-            this.chunkDataBuffer[8] = header.BitDepth;
-            this.chunkDataBuffer[9] = (byte)header.ColorType;
-            this.chunkDataBuffer[10] = header.CompressionMethod;
-            this.chunkDataBuffer[11] = header.FilterMethod;
-            this.chunkDataBuffer[12] = (byte)header.InterlaceMethod;
+            header.WriteTo(this.chunkDataBuffer);
 
-            this.WriteChunk(stream, PngChunkType.Header, this.chunkDataBuffer, 0, 13);
+            this.WriteChunk(stream, PngChunkType.Header, this.chunkDataBuffer, 0, PngHeader.Size);
         }
 
         /// <summary>
@@ -569,8 +630,8 @@ namespace SixLabors.ImageSharp.Formats.Png
             using (IManagedByteBuffer colorTable = this.memoryAllocator.AllocateManagedByteBuffer(colorTableLength))
             using (IManagedByteBuffer alphaTable = this.memoryAllocator.AllocateManagedByteBuffer(paletteLength))
             {
-                Span<byte> colorTableSpan = colorTable.GetSpan();
-                Span<byte> alphaTableSpan = alphaTable.GetSpan();
+                ref byte colorTableRef = ref MemoryMarshal.GetReference(colorTable.GetSpan());
+                ref byte alphaTableRef = ref MemoryMarshal.GetReference(alphaTable.GetSpan());
                 Span<byte> quantizedSpan = quantized.GetPixelSpan();
 
                 for (int i = 0; i < paletteLength; i++)
@@ -582,9 +643,9 @@ namespace SixLabors.ImageSharp.Formats.Png
 
                         byte alpha = rgba.A;
 
-                        colorTableSpan[offset] = rgba.R;
-                        colorTableSpan[offset + 1] = rgba.G;
-                        colorTableSpan[offset + 2] = rgba.B;
+                        Unsafe.Add(ref colorTableRef, offset) = rgba.R;
+                        Unsafe.Add(ref colorTableRef, offset + 1) = rgba.G;
+                        Unsafe.Add(ref colorTableRef, offset + 2) = rgba.B;
 
                         if (alpha > this.threshold)
                         {
@@ -592,7 +653,7 @@ namespace SixLabors.ImageSharp.Formats.Png
                         }
 
                         anyAlpha = anyAlpha || alpha < byte.MaxValue;
-                        alphaTableSpan[i] = alpha;
+                        Unsafe.Add(ref alphaTableRef, i) = alpha;
                     }
                 }
 
@@ -613,51 +674,9 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <param name="meta">The image meta data.</param>
         private void WritePhysicalChunk(Stream stream, ImageMetaData meta)
         {
-            // The pHYs chunk specifies the intended pixel size or aspect ratio for display of the image. It contains:
-            // Pixels per unit, X axis: 4 bytes (unsigned integer)
-            // Pixels per unit, Y axis: 4 bytes (unsigned integer)
-            // Unit specifier:          1 byte
-            //
-            // The following values are legal for the unit specifier:
-            //   0: unit is unknown
-            //   1: unit is the meter
-            //
-            // When the unit specifier is 0, the pHYs chunk defines pixel aspect ratio only; the actual size of the pixels remains unspecified.
-            Span<byte> hResolution = this.chunkDataBuffer.AsSpan(0, 4);
-            Span<byte> vResolution = this.chunkDataBuffer.AsSpan(4, 4);
-
-            switch (meta.ResolutionUnits)
-            {
-                case PixelResolutionUnit.AspectRatio:
-
-                    this.chunkDataBuffer[8] = 0;
-                    BinaryPrimitives.WriteInt32BigEndian(hResolution, (int)Math.Round(meta.HorizontalResolution));
-                    BinaryPrimitives.WriteInt32BigEndian(vResolution, (int)Math.Round(meta.VerticalResolution));
-                    break;
-
-                case PixelResolutionUnit.PixelsPerInch:
-
-                    this.chunkDataBuffer[8] = 1; // Per meter
-                    BinaryPrimitives.WriteInt32BigEndian(hResolution, (int)Math.Round(UnitConverter.InchToMeter(meta.HorizontalResolution)));
-                    BinaryPrimitives.WriteInt32BigEndian(vResolution, (int)Math.Round(UnitConverter.InchToMeter(meta.VerticalResolution)));
-                    break;
+            PhysicalChunkData.FromMetadata(meta).WriteTo(this.chunkDataBuffer);
 
-                case PixelResolutionUnit.PixelsPerCentimeter:
-
-                    this.chunkDataBuffer[8] = 1; // Per meter
-                    BinaryPrimitives.WriteInt32BigEndian(hResolution, (int)Math.Round(UnitConverter.CmToMeter(meta.HorizontalResolution)));
-                    BinaryPrimitives.WriteInt32BigEndian(vResolution, (int)Math.Round(UnitConverter.CmToMeter(meta.VerticalResolution)));
-                    break;
-
-                default:
-
-                    this.chunkDataBuffer[8] = 1; // Per meter
-                    BinaryPrimitives.WriteInt32BigEndian(hResolution, (int)Math.Round(meta.HorizontalResolution));
-                    BinaryPrimitives.WriteInt32BigEndian(vResolution, (int)Math.Round(meta.VerticalResolution));
-                    break;
-            }
-
-            this.WriteChunk(stream, PngChunkType.Physical, this.chunkDataBuffer, 0, 9);
+            this.WriteChunk(stream, PngChunkType.Physical, this.chunkDataBuffer, 0, PhysicalChunkData.Size);
         }
 
         /// <summary>
@@ -696,9 +715,9 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="pixels">The image.</param>
-        /// <param name="quantizedPixelsSpan">The span of quantized pixel data. Can be null.</param>
+        /// <param name="quantized">The quantized pixel data. Can be null.</param>
         /// <param name="stream">The stream.</param>
-        private void WriteDataChunks<TPixel>(ImageFrame<TPixel> pixels, ReadOnlySpan<byte> quantizedPixelsSpan, Stream stream)
+        private void WriteDataChunks<TPixel>(ImageFrame<TPixel> pixels, QuantizedFrame<TPixel> quantized, Stream stream)
             where TPixel : struct, IPixel<TPixel>
         {
             this.bytesPerScanline = this.CalculateScanlineLength(this.width);
@@ -714,26 +733,22 @@ namespace SixLabors.ImageSharp.Formats.Png
                     break;
 
                 case PngFilterMethod.Sub:
-
                     this.sub = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     break;
 
                 case PngFilterMethod.Up:
-
                     this.up = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     break;
 
                 case PngFilterMethod.Average:
-
                     this.average = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     break;
 
                 case PngFilterMethod.Paeth:
-
                     this.paeth = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     break;
-                case PngFilterMethod.Adaptive:
 
+                case PngFilterMethod.Adaptive:
                     this.sub = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     this.up = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
                     this.average = this.memoryAllocator.AllocateManagedByteBuffer(resultLength, AllocationOptions.Clean);
@@ -750,7 +765,7 @@ namespace SixLabors.ImageSharp.Formats.Png
                 {
                     for (int y = 0; y < this.height; y++)
                     {
-                        IManagedByteBuffer r = this.EncodePixelRow((ReadOnlySpan<TPixel>)pixels.GetPixelRowSpan(y), quantizedPixelsSpan, y);
+                        IManagedByteBuffer r = this.EncodePixelRow((ReadOnlySpan<TPixel>)pixels.GetPixelRowSpan(y), quantized, y);
                         deflateStream.Write(r.Array, 0, resultLength);
 
                         IManagedByteBuffer temp = this.rawScanline;
@@ -830,6 +845,47 @@ namespace SixLabors.ImageSharp.Formats.Png
             stream.Write(this.buffer, 0, 4); // write the crc
         }
 
+        /// <summary>
+        /// Packs the given 8 bit array into and array of <paramref name="bits"/> depths.
+        /// </summary>
+        /// <param name="source">The source span in 8 bits.</param>
+        /// <param name="result">The resultant span in <paramref name="bits"/>.</param>
+        /// <param name="bits">The bit depth.</param>
+        private void ScaleDownFrom8BitArray(ReadOnlySpan<byte> source, Span<byte> result, int bits)
+        {
+            ref byte sourceRef = ref MemoryMarshal.GetReference(source);
+            ref byte resultRef = ref MemoryMarshal.GetReference(result);
+
+            byte mask = (byte)(0xFF >> (8 - bits));
+            byte shift0 = (byte)(8 - bits);
+            int shift = 8 - bits;
+            int v = 0;
+            int resultOffset = 0;
+
+            for (int i = 0; i < source.Length; i++)
+            {
+                int value = Unsafe.Add(ref sourceRef, i) & mask;
+                v |= value << shift;
+
+                if (shift == 0)
+                {
+                    shift = shift0;
+                    Unsafe.Add(ref resultRef, resultOffset) = (byte)v;
+                    resultOffset++;
+                    v = 0;
+                }
+                else
+                {
+                    shift -= bits;
+                }
+            }
+
+            if (shift != shift0)
+            {
+                Unsafe.Add(ref resultRef, resultOffset) = (byte)v;
+            }
+        }
+
         /// <summary>
         /// Calculates the scanline length.
         /// </summary>

src/ImageSharp/Formats/Png/PngHeader.cs

@@ -1,6 +1,9 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
+using System.Buffers.Binary;
+
 namespace SixLabors.ImageSharp.Formats.Png
 {
     /// <summary>
@@ -8,6 +11,8 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// </summary>
     internal readonly struct PngHeader
     {
+        public const int Size = 13;
+
         public PngHeader(
             int width,
             int height,
@@ -74,5 +79,68 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Two values are currently defined: 0 (no interlace) or 1 (Adam7 interlace).
         /// </summary>
         public PngInterlaceMode InterlaceMethod { get; }
+
+        /// <summary>
+        /// Validates the png header.
+        /// </summary>
+        /// <exception cref="NotSupportedException">
+        /// Thrown if the image does pass validation.
+        /// </exception>
+        public void Validate()
+        {
+            if (!PngConstants.ColorTypes.TryGetValue(this.ColorType, out byte[] supportedBitDepths))
+            {
+                throw new NotSupportedException($"Invalid or unsupported color type. Was '{this.ColorType}'.");
+            }
+
+            if (supportedBitDepths.AsSpan().IndexOf(this.BitDepth) == -1)
+            {
+                throw new NotSupportedException($"Invalid or unsupported bit depth. Was '{this.BitDepth}'.");
+            }
+
+            if (this.FilterMethod != 0)
+            {
+                throw new NotSupportedException($"Invalid filter method. Expected 0. Was '{this.FilterMethod}'.");
+            }
+
+            // The png specification only defines 'None' and 'Adam7' as interlaced methods.
+            if (this.InterlaceMethod != PngInterlaceMode.None && this.InterlaceMethod != PngInterlaceMode.Adam7)
+            {
+                throw new NotSupportedException($"Invalid interlace method. Expected 'None' or 'Adam7'. Was '{this.InterlaceMethod}'.");
+            }
+        }
+
+        /// <summary>
+        /// Writes the header to the given buffer.
+        /// </summary>
+        /// <param name="buffer">The buffer to write to.</param>
+        public void WriteTo(Span<byte> buffer)
+        {
+            BinaryPrimitives.WriteInt32BigEndian(buffer.Slice(0, 4), this.Width);
+            BinaryPrimitives.WriteInt32BigEndian(buffer.Slice(4, 4), this.Height);
+
+            buffer[8] = this.BitDepth;
+            buffer[9] = (byte)this.ColorType;
+            buffer[10] = this.CompressionMethod;
+            buffer[11] = this.FilterMethod;
+            buffer[12] = (byte)this.InterlaceMethod;
+        }
+
+        /// <summary>
+        /// Parses the PngHeader from the given data buffer.
+        /// </summary>
+        /// <param name="data">The data to parse.</param>
+        /// <returns>The parsed PngHeader.</returns>
+        public static PngHeader Parse(ReadOnlySpan<byte> data)
+        {
+            return new PngHeader(
+              width: BinaryPrimitives.ReadInt32BigEndian(data.Slice(0, 4)),
+              height: BinaryPrimitives.ReadInt32BigEndian(data.Slice(4, 4)),
+              bitDepth: data[8],
+              colorType: (PngColorType)data[9],
+              compressionMethod: data[10],
+              filterMethod: data[11],
+              interlaceMethod: (PngInterlaceMode)data[12]);
+        }
     }
 }

src/ImageSharp/Formats/Png/PngMetaData.cs

@@ -6,8 +6,26 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// <summary>
     /// Provides Png specific metadata information for the image.
     /// </summary>
-    public class PngMetaData
+    public class PngMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PngMetaData"/> class.
+        /// </summary>
+        public PngMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PngMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        private PngMetaData(PngMetaData other)
+        {
+            this.BitDepth = other.BitDepth;
+            this.ColorType = other.ColorType;
+            this.Gamma = other.Gamma;
+        }
+
         /// <summary>
         /// Gets or sets the number of bits per sample or per palette index (not per pixel).
         /// Not all values are allowed for all <see cref="ColorType"/> values.
@@ -23,5 +41,8 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Gets or sets the gamma value for the image.
         /// </summary>
         public float Gamma { get; set; }
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new PngMetaData(this);
     }
 }

src/ImageSharp/Formats/Png/PngScanlineProcessor.cs

@@ -0,0 +1,600 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers.Binary;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Png
+{
+    /// <summary>
+    /// Provides methods to allow the decoding of raw scanlines to image rows of different pixel formats.
+    /// </summary>
+    internal static class PngScanlineProcessor
+    {
+        public static void ProcessGrayscaleScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            bool hasTrans,
+            ushort luminance16Trans,
+            byte luminanceTrans)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+            int scaleFactor = 255 / (ImageMaths.GetColorCountForBitDepth(header.BitDepth) - 1);
+
+            if (!hasTrans)
+            {
+                if (header.BitDepth == 16)
+                {
+                    Rgb48 rgb48 = default;
+                    for (int x = 0, o = 0; x < header.Width; x++, o += 2)
+                    {
+                        ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                        rgb48.R = luminance;
+                        rgb48.G = luminance;
+                        rgb48.B = luminance;
+
+                        pixel.PackFromRgb48(rgb48);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+                else
+                {
+                    // TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
+                    var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
+                    for (int x = 0; x < header.Width; x++)
+                    {
+                        byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
+                        rgba32.R = luminance;
+                        rgba32.G = luminance;
+                        rgba32.B = luminance;
+
+                        pixel.PackFromRgba32(rgba32);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+
+                return;
+            }
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = 0, o = 0; x < header.Width; x++, o += 2)
+                {
+                    ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                    rgba64.R = luminance;
+                    rgba64.G = luminance;
+                    rgba64.B = luminance;
+                    rgba64.A = luminance.Equals(luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                Rgba32 rgba32 = default;
+                for (int x = 0; x < header.Width; x++)
+                {
+                    byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
+                    rgba32.R = luminance;
+                    rgba32.G = luminance;
+                    rgba32.B = luminance;
+                    rgba32.A = luminance.Equals(luminanceTrans) ? byte.MinValue : byte.MaxValue;
+
+                    pixel.PackFromRgba32(rgba32);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessInterlacedGrayscaleScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int pixelOffset,
+            int increment,
+            bool hasTrans,
+            ushort luminance16Trans,
+            byte luminanceTrans)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+            int scaleFactor = 255 / (ImageMaths.GetColorCountForBitDepth(header.BitDepth) - 1);
+
+            if (!hasTrans)
+            {
+                if (header.BitDepth == 16)
+                {
+                    Rgb48 rgb48 = default;
+                    for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 2)
+                    {
+                        ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                        rgb48.R = luminance;
+                        rgb48.G = luminance;
+                        rgb48.B = luminance;
+
+                        pixel.PackFromRgb48(rgb48);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+                else
+                {
+                    // TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
+                    var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
+                    for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
+                    {
+                        byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, o) * scaleFactor);
+                        rgba32.R = luminance;
+                        rgba32.G = luminance;
+                        rgba32.B = luminance;
+
+                        pixel.PackFromRgba32(rgba32);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+
+                return;
+            }
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 2)
+                {
+                    ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                    rgba64.R = luminance;
+                    rgba64.G = luminance;
+                    rgba64.B = luminance;
+                    rgba64.A = luminance.Equals(luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                Rgba32 rgba32 = default;
+                for (int x = pixelOffset; x < header.Width; x += increment)
+                {
+                    byte luminance = (byte)(Unsafe.Add(ref scanlineSpanRef, x) * scaleFactor);
+                    rgba32.R = luminance;
+                    rgba32.G = luminance;
+                    rgba32.B = luminance;
+                    rgba32.A = luminance.Equals(luminanceTrans) ? byte.MinValue : byte.MaxValue;
+
+                    pixel.PackFromRgba32(rgba32);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessGrayscaleWithAlphaScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int bytesPerPixel,
+            int bytesPerSample)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = 0, o = 0; x < header.Width; x++, o += 4)
+                {
+                    ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                    ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
+                    rgba64.R = luminance;
+                    rgba64.G = luminance;
+                    rgba64.B = luminance;
+                    rgba64.A = alpha;
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                Rgba32 rgba32 = default;
+                int bps = bytesPerSample;
+                for (int x = 0; x < header.Width; x++)
+                {
+                    int offset = x * bytesPerPixel;
+                    byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
+                    byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + bps);
+
+                    rgba32.R = luminance;
+                    rgba32.G = luminance;
+                    rgba32.B = luminance;
+                    rgba32.A = alpha;
+
+                    pixel.PackFromRgba32(rgba32);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessInterlacedGrayscaleWithAlphaScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int pixelOffset,
+            int increment,
+            int bytesPerPixel,
+            int bytesPerSample)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += 4)
+                {
+                    ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
+                    ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
+                    rgba64.R = luminance;
+                    rgba64.G = luminance;
+                    rgba64.B = luminance;
+                    rgba64.A = alpha;
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                Rgba32 rgba32 = default;
+                for (int x = pixelOffset; x < header.Width; x += increment)
+                {
+                    int offset = x * bytesPerPixel;
+                    byte luminance = Unsafe.Add(ref scanlineSpanRef, offset);
+                    byte alpha = Unsafe.Add(ref scanlineSpanRef, offset + bytesPerSample);
+                    rgba32.R = luminance;
+                    rgba32.G = luminance;
+                    rgba32.B = luminance;
+                    rgba32.A = alpha;
+
+                    pixel.PackFromRgba32(rgba32);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessPaletteScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            ReadOnlySpan<byte> palette,
+            byte[] paletteAlpha)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+            ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(palette);
+            ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels);
+
+            if (paletteAlpha?.Length > 0)
+            {
+                // If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
+                // channel and we should try to read it.
+                Rgba32 rgba = default;
+                ref byte paletteAlphaRef = ref paletteAlpha[0];
+
+                for (int x = 0; x < header.Width; x++)
+                {
+                    int index = Unsafe.Add(ref scanlineSpanRef, x);
+                    rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
+                    rgba.A = paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                // TODO: We should have PackFromRgb24.
+                var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
+                for (int x = 0; x < header.Width; x++)
+                {
+                    int index = Unsafe.Add(ref scanlineSpanRef, x);
+                    rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessInterlacedPaletteScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int pixelOffset,
+            int increment,
+            ReadOnlySpan<byte> palette,
+            byte[] paletteAlpha)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+            ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(palette);
+            ref Rgb24 palettePixelsRef = ref MemoryMarshal.GetReference(palettePixels);
+
+            if (paletteAlpha?.Length > 0)
+            {
+                // If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
+                // channel and we should try to read it.
+                Rgba32 rgba = default;
+                ref byte paletteAlphaRef = ref paletteAlpha[0];
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
+                {
+                    int index = Unsafe.Add(ref scanlineSpanRef, o);
+                    rgba.A = paletteAlpha.Length > index ? Unsafe.Add(ref paletteAlphaRef, index) : byte.MaxValue;
+                    rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o++)
+                {
+                    int index = Unsafe.Add(ref scanlineSpanRef, o);
+                    rgba.Rgb = Unsafe.Add(ref palettePixelsRef, index);
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessRgbScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int bytesPerPixel,
+            int bytesPerSample,
+            bool hasTrans,
+            Rgb48 rgb48Trans,
+            Rgb24 rgb24Trans)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (!hasTrans)
+            {
+                if (header.BitDepth == 16)
+                {
+                    Rgb48 rgb48 = default;
+                    for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
+                    {
+                        rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                        rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                        rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+
+                        pixel.PackFromRgb48(rgb48);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+                else
+                {
+                    PixelOperations<TPixel>.Instance.PackFromRgb24Bytes(scanlineSpan, rowSpan, header.Width);
+                }
+
+                return;
+            }
+
+            if (header.BitDepth == 16)
+            {
+                Rgb48 rgb48 = default;
+                Rgba64 rgba64 = default;
+                for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
+                {
+                    rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                    rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                    rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+
+                    rgba64.Rgb = rgb48;
+                    rgba64.A = rgb48.Equals(rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                ReadOnlySpan<Rgb24> rgb24Span = MemoryMarshal.Cast<byte, Rgb24>(scanlineSpan);
+                ref Rgb24 rgb24SpanRef = ref MemoryMarshal.GetReference(rgb24Span);
+                for (int x = 0; x < header.Width; x++)
+                {
+                    ref readonly Rgb24 rgb24 = ref Unsafe.Add(ref rgb24SpanRef, x);
+                    Rgba32 rgba32 = default;
+                    rgba32.Rgb = rgb24;
+                    rgba32.A = rgb24.Equals(rgb24Trans) ? byte.MinValue : byte.MaxValue;
+
+                    pixel.PackFromRgba32(rgba32);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessInterlacedRgbScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int pixelOffset,
+            int increment,
+            int bytesPerPixel,
+            int bytesPerSample,
+            bool hasTrans,
+            Rgb48 rgb48Trans,
+            Rgb24 rgb24Trans)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (header.BitDepth == 16)
+            {
+                if (hasTrans)
+                {
+                    Rgb48 rgb48 = default;
+                    Rgba64 rgba64 = default;
+                    for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                    {
+                        rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                        rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                        rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+
+                        rgba64.Rgb = rgb48;
+                        rgba64.A = rgb48.Equals(rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
+
+                        pixel.PackFromRgba64(rgba64);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+                else
+                {
+                    Rgb48 rgb48 = default;
+                    for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                    {
+                        rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                        rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                        rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+
+                        pixel.PackFromRgb48(rgb48);
+                        Unsafe.Add(ref rowSpanRef, x) = pixel;
+                    }
+                }
+
+                return;
+            }
+
+            if (hasTrans)
+            {
+                Rgba32 rgba = default;
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                {
+                    rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
+                    rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
+                    rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
+                    rgba.A = rgb24Trans.Equals(rgba.Rgb) ? byte.MinValue : byte.MaxValue;
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                {
+                    rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
+                    rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
+                    rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+
+        public static void ProcessRgbaScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int bytesPerPixel,
+            int bytesPerSample)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = 0, o = 0; x < header.Width; x++, o += bytesPerPixel)
+                {
+                    rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                    rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                    rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+                    rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (3 * bytesPerSample), bytesPerSample));
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(scanlineSpan, rowSpan, header.Width);
+            }
+        }
+
+        public static void ProcessInterlacedRgbaScanline<TPixel>(
+            in PngHeader header,
+            ReadOnlySpan<byte> scanlineSpan,
+            Span<TPixel> rowSpan,
+            int pixelOffset,
+            int increment,
+            int bytesPerPixel,
+            int bytesPerSample)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            TPixel pixel = default;
+            ref byte scanlineSpanRef = ref MemoryMarshal.GetReference(scanlineSpan);
+            ref TPixel rowSpanRef = ref MemoryMarshal.GetReference(rowSpan);
+
+            if (header.BitDepth == 16)
+            {
+                Rgba64 rgba64 = default;
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                {
+                    rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, bytesPerSample));
+                    rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + bytesPerSample, bytesPerSample));
+                    rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (2 * bytesPerSample), bytesPerSample));
+                    rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + (3 * bytesPerSample), bytesPerSample));
+
+                    pixel.PackFromRgba64(rgba64);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+            else
+            {
+                Rgba32 rgba = default;
+                for (int x = pixelOffset, o = 0; x < header.Width; x += increment, o += bytesPerPixel)
+                {
+                    rgba.R = Unsafe.Add(ref scanlineSpanRef, o);
+                    rgba.G = Unsafe.Add(ref scanlineSpanRef, o + bytesPerSample);
+                    rgba.B = Unsafe.Add(ref scanlineSpanRef, o + (2 * bytesPerSample));
+                    rgba.A = Unsafe.Add(ref scanlineSpanRef, o + (3 * bytesPerSample));
+
+                    pixel.PackFromRgba32(rgba);
+                    Unsafe.Add(ref rowSpanRef, x) = pixel;
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Png/Zlib/ZlibInflateStream.cs

@@ -43,22 +43,24 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         private bool isDisposed;
 
         /// <summary>
-        /// Whether the crc value has been read.
+        /// The current data remaining to be read
         /// </summary>
-        private bool crcRead;
+        private int currentDataRemaining;
 
         /// <summary>
-        /// The current data remaining to be read
+        /// Delegate to get more data once we've exhausted the current data remaining
         /// </summary>
-        private int currentDataRemaining;
+        private readonly Func<int> getData;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ZlibInflateStream"/> class.
         /// </summary>
         /// <param name="innerStream">The inner raw stream</param>
-        public ZlibInflateStream(Stream innerStream)
+        /// <param name="getData">A delegate to get more data from the inner stream</param>
+        public ZlibInflateStream(Stream innerStream, Func<int> getData)
         {
             this.innerStream = innerStream;
+            this.getData = getData;
         }
 
         /// <inheritdoc/>
@@ -112,12 +114,36 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
         {
             if (this.currentDataRemaining == 0)
             {
-                return 0;
+                // last buffer was read in its entirety, let's make sure we don't actually have more
+                this.currentDataRemaining = this.getData();
+
+                if (this.currentDataRemaining == 0)
+                {
+                    return 0;
+                }
             }
 
             int bytesToRead = Math.Min(count, this.currentDataRemaining);
             this.currentDataRemaining -= bytesToRead;
-            return this.innerStream.Read(buffer, offset, bytesToRead);
+            int bytesRead = this.innerStream.Read(buffer, offset, bytesToRead);
+
+            // keep reading data until we've reached the end of the stream or filled the buffer
+            while (this.currentDataRemaining == 0 && bytesRead < count)
+            {
+                this.currentDataRemaining = this.getData();
+
+                if (this.currentDataRemaining == 0)
+                {
+                    return bytesRead;
+                }
+
+                offset += bytesRead;
+                bytesToRead = Math.Min(count - bytesRead, this.currentDataRemaining);
+                this.currentDataRemaining -= bytesToRead;
+                bytesRead += this.innerStream.Read(buffer, offset, bytesToRead);
+            }
+
+            return bytesRead;
         }
 
         /// <inheritdoc/>
@@ -153,14 +179,6 @@ namespace SixLabors.ImageSharp.Formats.Png.Zlib
                 {
                     this.compressedStream.Dispose();
                     this.compressedStream = null;
-
-                    if (!this.crcRead)
-                    {
-                        // Consume the trailing 4 bytes
-                        this.innerStream.Read(ChecksumBuffer, 0, 4);
-                        this.currentDataRemaining -= 4;
-                        this.crcRead = true;
-                    }
                 }
             }
 

src/ImageSharp/IDeepCloneable.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// A generic interface for a deeply cloneable type.
+    /// </summary>
+    /// <typeparam name="T">The type of object to clone.</typeparam>
+    public interface IDeepCloneable<out T>
+        where T : class
+    {
+        /// <summary>
+        /// Creates a new <typeparamref name="T"/> that is a deep copy of the current instance.
+        /// </summary>
+        /// <returns>The <typeparamref name="T"/>.</returns>
+        T DeepClone();
+    }
+
+    /// <summary>
+    /// An interface for objects that can be cloned. This creates a deep copy of the object.
+    /// </summary>
+    public interface IDeepCloneable
+    {
+        /// <summary>
+        /// Creates a new object that is a deep copy of the current instance.
+        /// </summary>
+        /// <returns>The <see cref="IDeepCloneable"/>.</returns>
+        IDeepCloneable DeepClone();
+    }
+}

src/ImageSharp/Image.Decode.cs

@@ -30,7 +30,7 @@ namespace SixLabors.ImageSharp
                 return null;
             }
 
-            using (IManagedByteBuffer buffer = config.MemoryAllocator.AllocateManagedByteBuffer(maxHeaderSize))
+            using (IManagedByteBuffer buffer = config.MemoryAllocator.AllocateManagedByteBuffer(maxHeaderSize, AllocationOptions.Clean))
             {
                 long startPosition = stream.Position;
                 stream.Read(buffer.Array, 0, maxHeaderSize);

src/ImageSharp/ImageFrameCollection.cs

@@ -94,7 +94,7 @@ namespace SixLabors.ImageSharp
         public ImageFrame<TPixel> InsertFrame(int index, ImageFrame<TPixel> source)
         {
             this.ValidateFrame(source);
-            ImageFrame<TPixel> clonedFrame = source.Clone();
+            ImageFrame<TPixel> clonedFrame = source.Clone(this.parent.GetConfiguration());
             this.frames.Insert(index, clonedFrame);
             return clonedFrame;
         }
@@ -107,7 +107,7 @@ namespace SixLabors.ImageSharp
         public ImageFrame<TPixel> AddFrame(ImageFrame<TPixel> source)
         {
             this.ValidateFrame(source);
-            ImageFrame<TPixel> clonedFrame = source.Clone();
+            ImageFrame<TPixel> clonedFrame = source.Clone(this.parent.GetConfiguration());
             this.frames.Add(clonedFrame);
             return clonedFrame;
         }
@@ -155,10 +155,7 @@ namespace SixLabors.ImageSharp
         /// <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);
-        }
+        public bool Contains(ImageFrame<TPixel> frame) => this.frames.Contains(frame);
 
         /// <summary>
         /// Moves an <seealso cref="ImageFrame{TPixel}"/> from <paramref name="sourceIndex"/> to <paramref name="destinationIndex"/>.
@@ -195,7 +192,7 @@ namespace SixLabors.ImageSharp
 
             this.frames.Remove(frame);
 
-            return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.Clone(), new[] { frame });
+            return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.DeepClone(), new[] { frame });
         }
 
         /// <summary>
@@ -208,7 +205,7 @@ namespace SixLabors.ImageSharp
         {
             ImageFrame<TPixel> frame = this[index];
             ImageFrame<TPixel> clonedFrame = frame.Clone();
-            return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.Clone(), new[] { clonedFrame });
+            return new Image<TPixel>(this.parent.GetConfiguration(), this.parent.MetaData.DeepClone(), new[] { clonedFrame });
         }
 
         /// <summary>
@@ -217,10 +214,7 @@ namespace SixLabors.ImageSharp
         /// <returns>
         /// The new <see cref="ImageFrame{TPixel}" />.
         /// </returns>
-        public ImageFrame<TPixel> CreateFrame()
-        {
-            return this.CreateFrame(default);
-        }
+        public ImageFrame<TPixel> CreateFrame() => this.CreateFrame(default);
 
         /// <summary>
         /// Creates a new <seealso cref="ImageFrame{TPixel}" /> and appends it to the end of the collection.

src/ImageSharp/ImageFrame{TPixel}.cs

@@ -9,6 +9,7 @@ using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.MetaData;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -95,6 +96,10 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class wrapping an existing buffer.
         /// </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="memorySource">The memory source.</param>
         internal ImageFrame(Configuration configuration, int width, int height, MemorySource<TPixel> memorySource)
             : this(configuration, width, height, memorySource, new ImageFrameMetaData())
         {
@@ -103,12 +108,12 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrame{TPixel}" /> class wrapping an existing buffer.
         /// </summary>
-        internal ImageFrame(
-            Configuration configuration,
-            int width,
-            int height,
-            MemorySource<TPixel> memorySource,
-            ImageFrameMetaData metaData)
+        /// <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="memorySource">The memory source.</param>
+        /// <param name="metaData">The meta data.</param>
+        internal ImageFrame(Configuration configuration, int width, int height, MemorySource<TPixel> memorySource, ImageFrameMetaData metaData)
         {
             Guard.NotNull(configuration, nameof(configuration));
             Guard.MustBeGreaterThan(width, 0, nameof(width));
@@ -135,7 +140,7 @@ namespace SixLabors.ImageSharp
             this.MemoryAllocator = configuration.MemoryAllocator;
             this.PixelBuffer = this.MemoryAllocator.Allocate2D<TPixel>(source.PixelBuffer.Width, source.PixelBuffer.Height);
             source.PixelBuffer.GetSpan().CopyTo(this.PixelBuffer.GetSpan());
-            this.MetaData = source.MetaData.Clone();
+            this.MetaData = source.MetaData.DeepClone();
         }
 
         /// <summary>
@@ -247,35 +252,61 @@ namespace SixLabors.ImageSharp
         /// <inheritdoc/>
         public override string ToString() => $"ImageFrame<{typeof(TPixel).Name}>: {this.Width}x{this.Height}";
 
+        /// <summary>
+        /// Clones the current instance.
+        /// </summary>
+        /// <returns>The <see cref="ImageFrame{TPixel}"/></returns>
+        internal ImageFrame<TPixel> Clone() => this.Clone(this.configuration);
+
+        /// <summary>
+        /// Clones the current instance.
+        /// </summary>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <returns>The <see cref="ImageFrame{TPixel}"/></returns>
+        internal ImageFrame<TPixel> Clone(Configuration configuration) => new ImageFrame<TPixel>(configuration, this);
+
         /// <summary>
         /// Returns a copy of the image frame in the given pixel format.
         /// </summary>
         /// <typeparam name="TPixel2">The pixel format.</typeparam>
         /// <returns>The <see cref="ImageFrame{TPixel2}"/></returns>
         internal ImageFrame<TPixel2> CloneAs<TPixel2>()
+            where TPixel2 : struct, IPixel<TPixel2> => this.CloneAs<TPixel2>(this.configuration);
+
+        /// <summary>
+        /// Returns a copy of the image frame in the given pixel format.
+        /// </summary>
+        /// <typeparam name="TPixel2">The pixel format.</typeparam>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <returns>The <see cref="ImageFrame{TPixel2}"/></returns>
+        internal ImageFrame<TPixel2> CloneAs<TPixel2>(Configuration configuration)
             where TPixel2 : struct, IPixel<TPixel2>
         {
             if (typeof(TPixel2) == typeof(TPixel))
             {
-                return this.Clone() as ImageFrame<TPixel2>;
+                return this.Clone(configuration) as ImageFrame<TPixel2>;
             }
 
-            var target = new ImageFrame<TPixel2>(this.configuration, this.Width, this.Height, this.MetaData.Clone());
-
-            ParallelFor.WithTemporaryBuffer(
-                0,
-                this.Height,
-                this.configuration,
-                this.Width,
-                (int y, IMemoryOwner<Vector4> tempRowBuffer) =>
-                {
-                    Span<TPixel> sourceRow = this.GetPixelRowSpan(y);
-                    Span<TPixel2> targetRow = target.GetPixelRowSpan(y);
-                    Span<Vector4> tempRowSpan = tempRowBuffer.GetSpan();
-
-                    PixelOperations<TPixel>.Instance.ToScaledVector4(sourceRow, tempRowSpan, sourceRow.Length);
-                    PixelOperations<TPixel2>.Instance.PackFromScaledVector4(tempRowSpan, targetRow, targetRow.Length);
-                });
+            var target = new ImageFrame<TPixel2>(configuration, this.Width, this.Height, this.MetaData.DeepClone());
+
+            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
+                this.Bounds(),
+                configuration,
+                (rows, tempRowBuffer) =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            Span<TPixel> sourceRow = this.GetPixelRowSpan(y);
+                            Span<TPixel2> targetRow = target.GetPixelRowSpan(y);
+                            Span<Vector4> tempRowSpan = tempRowBuffer.Span;
+
+                            PixelOperations<TPixel>.Instance.ToScaledVector4(sourceRow, tempRowSpan, sourceRow.Length);
+                            PixelOperations<TPixel2>.Instance.PackFromScaledVector4(
+                                tempRowSpan,
+                                targetRow,
+                                targetRow.Length);
+                        }
+                    });
 
             return target;
         }
@@ -287,22 +318,17 @@ namespace SixLabors.ImageSharp
         /// <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);
-                });
-        }
+            Span<TPixel> span = this.GetPixelSpan();
 
-        /// <summary>
-        /// Clones the current instance.
-        /// </summary>
-        /// <returns>The <see cref="ImageFrame{TPixel}"/></returns>
-        internal ImageFrame<TPixel> Clone() => new ImageFrame<TPixel>(this.configuration, this);
+            if (value.Equals(default))
+            {
+                span.Clear();
+            }
+            else
+            {
+                span.Fill(value);
+            }
+        }
 
         /// <inheritdoc/>
         void IDisposable.Dispose() => this.Dispose();

src/ImageSharp/ImageSharp.csproj.DotSettings

@@ -0,0 +1,3 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=common/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=common_005Cexceptions/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

src/ImageSharp/Image{TPixel}.cs

@@ -11,7 +11,6 @@ using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Memory;
 
 namespace SixLabors.ImageSharp
 {
@@ -23,15 +22,12 @@ namespace SixLabors.ImageSharp
         where TPixel : struct, IPixel<TPixel>
     {
         private readonly Configuration configuration;
-        private readonly ImageFrameCollection<TPixel> frames;
 
         /// <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="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>
         public Image(Configuration configuration, int width, int height)
@@ -43,9 +39,7 @@ namespace SixLabors.ImageSharp
         /// 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="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>
@@ -69,9 +63,7 @@ namespace SixLabors.ImageSharp
         /// 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="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="metadata">The images metadata.</param>
@@ -80,37 +72,41 @@ 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, default(TPixel));
+            this.Frames = new ImageFrameCollection<TPixel>(this, width, height, default(TPixel));
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
         /// wrapping an external <see cref="MemorySource{T}"/>
         /// </summary>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <param name="memorySource">The memory source.</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 images metadata.</param>
         internal Image(Configuration configuration, MemorySource<TPixel> memorySource, int width, int height, ImageMetaData metadata)
         {
             this.configuration = configuration;
             this.PixelType = new PixelTypeInfo(Unsafe.SizeOf<TPixel>() * 8);
             this.MetaData = metadata;
-            this.frames = new ImageFrameCollection<TPixel>(this, width, height, memorySource);
+            this.Frames = new ImageFrameCollection<TPixel>(this, width, height, memorySource);
         }
 
         /// <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="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) {
+        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);
+            this.Frames = new ImageFrameCollection<TPixel>(this, width, height, backgroundColor);
         }
 
         /// <summary>
@@ -126,7 +122,7 @@ namespace SixLabors.ImageSharp
             this.PixelType = new PixelTypeInfo(Unsafe.SizeOf<TPixel>() * 8);
             this.MetaData = metadata ?? new ImageMetaData();
 
-            this.frames = new ImageFrameCollection<TPixel>(this, frames);
+            this.Frames = new ImageFrameCollection<TPixel>(this, frames);
         }
 
         /// <summary>
@@ -138,10 +134,10 @@ namespace SixLabors.ImageSharp
         public PixelTypeInfo PixelType { get; }
 
         /// <inheritdoc/>
-        public int Width => this.frames.RootFrame.Width;
+        public int Width => this.Frames.RootFrame.Width;
 
         /// <inheritdoc/>
-        public int Height => this.frames.RootFrame.Height;
+        public int Height => this.Frames.RootFrame.Height;
 
         /// <inheritdoc/>
         public ImageMetaData MetaData { get; }
@@ -149,12 +145,12 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Gets the frames.
         /// </summary>
-        public ImageFrameCollection<TPixel> Frames => this.frames;
+        public ImageFrameCollection<TPixel> Frames { get; }
 
         /// <summary>
         /// Gets the root frame.
         /// </summary>
-        private IPixelSource<TPixel> PixelSource => this.frames?.RootFrame ?? throw new ObjectDisposedException(nameof(Image<TPixel>));
+        private IPixelSource<TPixel> PixelSource => this.Frames?.RootFrame ?? throw new ObjectDisposedException(nameof(Image<TPixel>));
 
         /// <summary>
         /// Gets or sets the pixel at the specified position.
@@ -187,16 +183,17 @@ namespace SixLabors.ImageSharp
         /// Clones the current image
         /// </summary>
         /// <returns>Returns a new image with all the same metadata as the original.</returns>
-        public Image<TPixel> Clone()
-        {
-            IEnumerable<ImageFrame<TPixel>> clonedFrames = this.frames.Select(x => x.Clone());
-            return new Image<TPixel>(this.configuration, this.MetaData.Clone(), clonedFrames);
-        }
+        public Image<TPixel> Clone() => this.Clone(this.configuration);
 
-        /// <inheritdoc/>
-        public override string ToString()
+        /// <summary>
+        /// Clones the current image with the given configueation.
+        /// </summary>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <returns>Returns a new <see cref="Image{TPixel}"/> with all the same pixel data as the original.</returns>
+        public Image<TPixel> Clone(Configuration configuration)
         {
-            return $"Image<{typeof(TPixel).Name}>: {this.Width}x{this.Height}";
+            IEnumerable<ImageFrame<TPixel>> clonedFrames = this.Frames.Select(x => x.Clone(configuration));
+            return new Image<TPixel>(configuration, this.MetaData.DeepClone(), clonedFrames);
         }
 
         /// <summary>
@@ -205,22 +202,27 @@ namespace SixLabors.ImageSharp
         /// <typeparam name="TPixel2">The pixel format.</typeparam>
         /// <returns>The <see cref="Image{TPixel2}"/></returns>
         public Image<TPixel2> CloneAs<TPixel2>()
-            where TPixel2 : struct, IPixel<TPixel2>
-        {
-            IEnumerable<ImageFrame<TPixel2>> clonedFrames = this.frames.Select(x => x.CloneAs<TPixel2>());
-            var target = new Image<TPixel2>(this.configuration, this.MetaData.Clone(), clonedFrames);
-
-            return target;
-        }
+            where TPixel2 : struct, IPixel<TPixel2> => this.CloneAs<TPixel2>(this.configuration);
 
         /// <summary>
-        /// Releases managed resources.
+        /// Returns a copy of the image in the given pixel format.
         /// </summary>
-        public void Dispose()
+        /// <typeparam name="TPixel2">The pixel format.</typeparam>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <returns>The <see cref="Image{TPixel2}"/></returns>
+        public Image<TPixel2> CloneAs<TPixel2>(Configuration configuration)
+            where TPixel2 : struct, IPixel<TPixel2>
         {
-            this.frames.Dispose();
+            IEnumerable<ImageFrame<TPixel2>> clonedFrames = this.Frames.Select(x => x.CloneAs<TPixel2>(configuration));
+            return new Image<TPixel2>(configuration, this.MetaData.DeepClone(), clonedFrames);
         }
 
+        /// <inheritdoc/>
+        public void Dispose() => this.Frames.Dispose();
+
+        /// <inheritdoc/>
+        public override string ToString() => $"Image<{typeof(TPixel).Name}>: {this.Width}x{this.Height}";
+
         /// <summary>
         /// Switches the buffers used by the image and the pixelSource meaning that the Image will "own" the buffer from the pixelSource and the pixelSource will now own the Images buffer.
         /// </summary>
@@ -229,9 +231,9 @@ namespace SixLabors.ImageSharp
         {
             Guard.NotNull(pixelSource, nameof(pixelSource));
 
-            for (int i = 0; i < this.frames.Count; i++)
+            for (int i = 0; i < this.Frames.Count; i++)
             {
-                this.frames[i].SwapOrCopyPixelsBufferFrom(pixelSource.frames[i]);
+                this.Frames[i].SwapOrCopyPixelsBufferFrom(pixelSource.Frames[i]);
             }
         }
     }

src/ImageSharp/Memory/Buffer2DExtensions.cs

@@ -96,15 +96,14 @@ namespace SixLabors.ImageSharp.Memory
         /// <param name="buffer">The <see cref="Buffer2D{T}"/></param>
         /// <param name="rectangle">The rectangle subarea</param>
         /// <returns>The <see cref="BufferArea{T}"/></returns>
-        public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer, Rectangle rectangle)
+        public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer, in Rectangle rectangle)
             where T : struct => new BufferArea<T>(buffer, rectangle);
 
         public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer, int x, int y, int width, int height)
-            where T : struct
-        {
-            var rectangle = new Rectangle(x, y, width, height);
-            return new BufferArea<T>(buffer, rectangle);
-        }
+            where T : struct => new BufferArea<T>(buffer, new Rectangle(x, y, width, height));
+
+        public static BufferArea<T> GetAreaBetweenRows<T>(this Buffer2D<T> buffer, int minY, int maxY)
+            where T : struct => new BufferArea<T>(buffer, new Rectangle(0, minY, buffer.Width, maxY - minY));
 
         /// <summary>
         /// Return a <see cref="BufferArea{T}"/> to the whole area of 'buffer'
@@ -114,5 +113,14 @@ namespace SixLabors.ImageSharp.Memory
         /// <returns>The <see cref="BufferArea{T}"/></returns>
         public static BufferArea<T> GetArea<T>(this Buffer2D<T> buffer)
             where T : struct => new BufferArea<T>(buffer);
+
+        /// <summary>
+        /// Gets a span for all the pixels in <paramref name="buffer"/> defined by <paramref name="rows"/>
+        /// </summary>
+        public static Span<T> GetMultiRowSpan<T>(this Buffer2D<T> buffer, in RowInterval rows)
+            where T : struct
+        {
+            return buffer.Span.Slice(rows.Min * buffer.Width, rows.Height * buffer.Width);
+        }
     }
 }

src/ImageSharp/Memory/RowInterval.cs

@@ -0,0 +1,45 @@
+// Copyright(c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Memory
+{
+    /// <summary>
+    /// Represents an interval of rows in a <see cref="Rectangle"/> and/or <see cref="Buffer2D{T}"/>
+    /// </summary>
+    internal readonly struct RowInterval
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RowInterval"/> struct.
+        /// </summary>
+        public RowInterval(int min, int max)
+        {
+            DebugGuard.MustBeLessThan(min, max, nameof(min));
+
+            this.Min = min;
+            this.Max = max;
+        }
+
+        /// <summary>
+        /// Gets the INCLUSIVE minimum
+        /// </summary>
+        public int Min { get; }
+
+        /// <summary>
+        /// Gets the EXCLUSIVE maximum
+        /// </summary>
+        public int Max { get; }
+
+        /// <summary>
+        /// Gets the difference (<see cref="Max"/> - <see cref="Min"/>)
+        /// </summary>
+        public int Height => this.Max - this.Min;
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"RowInterval [{this.Min}->{this.Max}[";
+        }
+    }
+}

src/ImageSharp/MetaData/ImageFrameMetaData.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
 using System.Collections.Generic;
 using SixLabors.ImageSharp.Formats;
 
@@ -10,9 +9,9 @@ namespace SixLabors.ImageSharp.MetaData
     /// <summary>
     /// Encapsulates the metadata of an image frame.
     /// </summary>
-    public sealed class ImageFrameMetaData
+    public sealed class ImageFrameMetaData : IDeepCloneable<ImageFrameMetaData>
     {
-        private readonly Dictionary<IImageFormat, object> formatMetaData = new Dictionary<IImageFormat, object>();
+        private readonly Dictionary<IImageFormat, IDeepCloneable> formatMetaData = new Dictionary<IImageFormat, IDeepCloneable>();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrameMetaData"/> class.
@@ -32,17 +31,14 @@ namespace SixLabors.ImageSharp.MetaData
         {
             DebugGuard.NotNull(other, nameof(other));
 
-            foreach (KeyValuePair<IImageFormat, object> meta in other.formatMetaData)
+            foreach (KeyValuePair<IImageFormat, IDeepCloneable> meta in other.formatMetaData)
             {
-                this.formatMetaData.Add(meta.Key, meta.Value);
+                this.formatMetaData.Add(meta.Key, meta.Value.DeepClone());
             }
         }
 
-        /// <summary>
-        /// Clones this ImageFrameMetaData.
-        /// </summary>
-        /// <returns>The cloned instance.</returns>
-        public ImageFrameMetaData Clone() => new ImageFrameMetaData(this);
+        /// <inheritdoc/>
+        public ImageFrameMetaData DeepClone() => new ImageFrameMetaData(this);
 
         /// <summary>
         /// Gets the metadata value associated with the specified key.
@@ -55,9 +51,9 @@ namespace SixLabors.ImageSharp.MetaData
         /// </returns>
         public TFormatFrameMetaData GetFormatMetaData<TFormatMetaData, TFormatFrameMetaData>(IImageFormat<TFormatMetaData, TFormatFrameMetaData> key)
             where TFormatMetaData : class
-            where TFormatFrameMetaData : class
+            where TFormatFrameMetaData : class, IDeepCloneable
         {
-            if (this.formatMetaData.TryGetValue(key, out object meta))
+            if (this.formatMetaData.TryGetValue(key, out IDeepCloneable meta))
             {
                 return (TFormatFrameMetaData)meta;
             }

src/ImageSharp/MetaData/ImageMetaData.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
 using System.Collections.Generic;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
@@ -12,7 +11,7 @@ namespace SixLabors.ImageSharp.MetaData
     /// <summary>
     /// Encapsulates the metadata of an image.
     /// </summary>
-    public sealed class ImageMetaData
+    public sealed class ImageMetaData : IDeepCloneable<ImageMetaData>
     {
         /// <summary>
         /// The default horizontal resolution value (dots per inch) in x direction.
@@ -26,7 +25,13 @@ namespace SixLabors.ImageSharp.MetaData
         /// </summary>
         public const double DefaultVerticalResolution = 96;
 
-        private readonly Dictionary<IImageFormat, object> formatMetaData = new Dictionary<IImageFormat, object>();
+        /// <summary>
+        /// The default pixel resolution units.
+        /// <remarks>The default value is <see cref="PixelResolutionUnit.PixelsPerInch"/>.</remarks>
+        /// </summary>
+        public const PixelResolutionUnit DefaultPixelResolutionUnits = PixelResolutionUnit.PixelsPerInch;
+
+        private readonly Dictionary<IImageFormat, IDeepCloneable> formatMetaData = new Dictionary<IImageFormat, IDeepCloneable>();
         private double horizontalResolution;
         private double verticalResolution;
 
@@ -37,6 +42,7 @@ namespace SixLabors.ImageSharp.MetaData
         {
             this.horizontalResolution = DefaultHorizontalResolution;
             this.verticalResolution = DefaultVerticalResolution;
+            this.ResolutionUnits = DefaultPixelResolutionUnits;
         }
 
         /// <summary>
@@ -52,9 +58,9 @@ namespace SixLabors.ImageSharp.MetaData
             this.VerticalResolution = other.VerticalResolution;
             this.ResolutionUnits = other.ResolutionUnits;
 
-            foreach (KeyValuePair<IImageFormat, object> meta in other.formatMetaData)
+            foreach (KeyValuePair<IImageFormat, IDeepCloneable> meta in other.formatMetaData)
             {
-                this.formatMetaData.Add(meta.Key, meta.Value);
+                this.formatMetaData.Add(meta.Key, meta.Value.DeepClone());
             }
 
             foreach (ImageProperty property in other.Properties)
@@ -62,13 +68,8 @@ namespace SixLabors.ImageSharp.MetaData
                 this.Properties.Add(property);
             }
 
-            this.ExifProfile = other.ExifProfile != null
-                ? new ExifProfile(other.ExifProfile)
-                : null;
-
-            this.IccProfile = other.IccProfile != null
-                ? new IccProfile(other.IccProfile)
-                : null;
+            this.ExifProfile = other.ExifProfile?.DeepClone();
+            this.IccProfile = other.IccProfile?.DeepClone();
         }
 
         /// <summary>
@@ -114,7 +115,7 @@ namespace SixLabors.ImageSharp.MetaData
         ///  02 : Pixels per centimeter
         ///  03 : Pixels per meter
         /// </summary>
-        public PixelResolutionUnit ResolutionUnits { get; set; } = PixelResolutionUnit.PixelsPerInch;
+        public PixelResolutionUnit ResolutionUnits { get; set; }
 
         /// <summary>
         /// Gets or sets the Exif profile.
@@ -140,9 +141,9 @@ namespace SixLabors.ImageSharp.MetaData
         /// The <typeparamref name="TFormatMetaData"/>.
         /// </returns>
         public TFormatMetaData GetFormatMetaData<TFormatMetaData>(IImageFormat<TFormatMetaData> key)
-             where TFormatMetaData : class
+             where TFormatMetaData : class, IDeepCloneable
         {
-            if (this.formatMetaData.TryGetValue(key, out object meta))
+            if (this.formatMetaData.TryGetValue(key, out IDeepCloneable meta))
             {
                 return (TFormatMetaData)meta;
             }
@@ -152,11 +153,8 @@ namespace SixLabors.ImageSharp.MetaData
             return newMeta;
         }
 
-        /// <summary>
-        /// Clones this into a new instance
-        /// </summary>
-        /// <returns>The cloned metadata instance</returns>
-        public ImageMetaData Clone() => new ImageMetaData(this);
+        /// <inheritdoc/>
+        public ImageMetaData DeepClone() => new ImageMetaData(this);
 
         /// <summary>
         /// Looks up a property with the provided name.

src/ImageSharp/MetaData/Profiles/Exif/ExifProfile.cs

@@ -12,23 +12,18 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
     /// <summary>
     /// Represents an EXIF profile providing access to the collection of values.
     /// </summary>
-    public sealed class ExifProfile
+    public sealed class ExifProfile : IDeepCloneable<ExifProfile>
     {
         /// <summary>
         /// The byte array to read the EXIF profile from.
         /// </summary>
-        private byte[] data;
+        private readonly byte[] data;
 
         /// <summary>
         /// The collection of EXIF values
         /// </summary>
         private List<ExifValue> values;
 
-        /// <summary>
-        /// The list of invalid EXIF tags
-        /// </summary>
-        private IReadOnlyList<ExifTag> invalidTags;
-
         /// <summary>
         /// The thumbnail offset position in the byte stream
         /// </summary>
@@ -55,7 +50,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         {
             this.Parts = ExifParts.All;
             this.data = data;
-            this.invalidTags = new List<ExifTag>();
+            this.InvalidTags = new List<ExifTag>();
         }
 
         /// <summary>
@@ -63,22 +58,19 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// by making a copy from another EXIF profile.
         /// </summary>
         /// <param name="other">The other EXIF profile, where the clone should be made from.</param>
-        /// <exception cref="System.ArgumentNullException"><paramref name="other"/> is null.</exception>
-        public ExifProfile(ExifProfile other)
+        private ExifProfile(ExifProfile other)
         {
-            Guard.NotNull(other, nameof(other));
-
             this.Parts = other.Parts;
             this.thumbnailLength = other.thumbnailLength;
             this.thumbnailOffset = other.thumbnailOffset;
-            this.invalidTags = new List<ExifTag>(other.invalidTags);
+            this.InvalidTags = new List<ExifTag>(other.InvalidTags);
             if (other.values != null)
             {
                 this.values = new List<ExifValue>(other.Values.Count);
 
                 foreach (ExifValue value in other.Values)
                 {
-                    this.values.Add(new ExifValue(value));
+                    this.values.Add(value.DeepClone());
                 }
             }
 
@@ -97,7 +89,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <summary>
         /// Gets the tags that where found but contained an invalid value.
         /// </summary>
-        public IReadOnlyList<ExifTag> InvalidTags => this.invalidTags;
+        public IReadOnlyList<ExifTag> InvalidTags { get; private set; }
 
         /// <summary>
         /// Gets the values of this EXIF profile.
@@ -249,6 +241,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return writer.GetData();
         }
 
+        /// <inheritdoc/>
+        public ExifProfile DeepClone() => new ExifProfile(this);
+
         /// <summary>
         /// Synchronizes the profiles with the specified meta data.
         /// </summary>
@@ -294,7 +289,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
             this.values = reader.ReadValues();
 
-            this.invalidTags = new List<ExifTag>(reader.InvalidTags);
+            this.InvalidTags = new List<ExifTag>(reader.InvalidTags);
             this.thumbnailOffset = (int)reader.ThumbnailOffset;
             this.thumbnailLength = (int)reader.ThumbnailLength;
         }

src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs

@@ -127,25 +127,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
         private unsafe string ConvertToString(ReadOnlySpan<byte> buffer)
         {
-            Span<byte> nullChar = stackalloc byte[1] { 0 };
-
-            int nullCharIndex = buffer.IndexOf(nullChar);
+            int nullCharIndex = buffer.IndexOf((byte)0);
 
             if (nullCharIndex > -1)
             {
                 buffer = buffer.Slice(0, nullCharIndex);
             }
 
-#if NETSTANDARD1_1
-            return Encoding.UTF8.GetString(buffer.ToArray(), 0, buffer.Length);
-#elif NETCOREAPP2_1
             return Encoding.UTF8.GetString(buffer);
-#else
-            fixed (byte* pointer = &MemoryMarshal.GetReference(buffer))
-            {
-                return Encoding.UTF8.GetString(pointer, buffer.Length);
-            }
-#endif
         }
 
         /// <summary>

src/ImageSharp/MetaData/Profiles/Exif/ExifValue.cs

@@ -11,15 +11,30 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
     /// <summary>
     /// Represent the value of the EXIF profile.
     /// </summary>
-    public sealed class ExifValue : IEquatable<ExifValue>
+    public sealed class ExifValue : IEquatable<ExifValue>, IDeepCloneable<ExifValue>
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ExifValue"/> class.
+        /// </summary>
+        /// <param name="tag">The tag.</param>
+        /// <param name="dataType">The data type.</param>
+        /// <param name="value">The value.</param>
+        /// <param name="isArray">Whether the value is an array.</param>
+        internal ExifValue(ExifTag tag, ExifDataType dataType, object value, bool isArray)
+        {
+            this.Tag = tag;
+            this.DataType = dataType;
+            this.IsArray = isArray && dataType != ExifDataType.Ascii;
+            this.Value = value;
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ExifValue"/> class
         /// by making a copy from another exif value.
         /// </summary>
         /// <param name="other">The other exif value, where the clone should be made from.</param>
-        /// <exception cref="System.ArgumentNullException"><paramref name="other"/> is null.</exception>
-        public ExifValue(ExifValue other)
+        /// <exception cref="ArgumentNullException"><paramref name="other"/> is null.</exception>
+        private ExifValue(ExifValue other)
         {
             Guard.NotNull(other, nameof(other));
 
@@ -29,30 +44,17 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
             if (!other.IsArray)
             {
+                // All types are value types except for string which is immutable so safe to simply assign.
                 this.Value = other.Value;
             }
             else
             {
+                // All array types are value types so Clone() is sufficient here.
                 var array = (Array)other.Value;
                 this.Value = array.Clone();
             }
         }
 
-        /// <summary>
-        /// Initializes a new instance of the <see cref="ExifValue"/> class.
-        /// </summary>
-        /// <param name="tag">The tag.</param>
-        /// <param name="dataType">The data type.</param>
-        /// <param name="value">The value.</param>
-        /// <param name="isArray">Whether the value is an array.</param>
-        internal ExifValue(ExifTag tag, ExifDataType dataType, object value, bool isArray)
-        {
-            this.Tag = tag;
-            this.DataType = dataType;
-            this.IsArray = isArray && dataType != ExifDataType.Ascii;
-            this.Value = value;
-        }
-
         /// <summary>
         /// Gets the data type of the exif value.
         /// </summary>
@@ -145,10 +147,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <returns>
         /// True if the <paramref name="left"/> parameter is equal to the <paramref name="right"/> parameter; otherwise, false.
         /// </returns>
-        public static bool operator ==(ExifValue left, ExifValue right)
-        {
-            return ReferenceEquals(left, right) || left.Equals(right);
-        }
+        public static bool operator ==(ExifValue left, ExifValue right) => ReferenceEquals(left, right) || left.Equals(right);
 
         /// <summary>
         /// Compares two <see cref="ExifValue"/> objects for equality.
@@ -162,16 +161,10 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <returns>
         /// True if the <paramref name="left"/> parameter is not equal to the <paramref name="right"/> parameter; otherwise, false.
         /// </returns>
-        public static bool operator !=(ExifValue left, ExifValue right)
-        {
-            return !(left == right);
-        }
+        public static bool operator !=(ExifValue left, ExifValue right) => !(left == right);
 
         /// <inheritdoc />
-        public override bool Equals(object obj)
-        {
-            return obj is ExifValue other && this.Equals(other);
-        }
+        public override bool Equals(object obj) => obj is ExifValue other && this.Equals(other);
 
         /// <inheritdoc />
         public bool Equals(ExifValue other)
@@ -187,9 +180,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             }
 
             return
-              this.Tag == other.Tag &&
-              this.DataType == other.DataType &&
-              object.Equals(this.Value, other.Value);
+              this.Tag == other.Tag
+              && this.DataType == other.DataType
+              && object.Equals(this.Value, other.Value);
         }
 
         /// <summary>
@@ -205,10 +198,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         }
 
         /// <inheritdoc/>
-        public override int GetHashCode()
-        {
-            return this.GetHashCode(this);
-        }
+        public override int GetHashCode() => this.GetHashCode(this);
 
         /// <inheritdoc/>
         public override string ToString()
@@ -238,6 +228,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return sb.ToString();
         }
 
+        /// <inheritdoc/>
+        public ExifValue DeepClone() => new ExifValue(this);
+
         /// <summary>
         /// Creates a new <see cref="ExifValue"/>
         /// </summary>
@@ -584,7 +577,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         private static ExifValue CreateNumber(ExifTag tag, object value, bool isArray)
         {
             Type type = value?.GetType();
-            if (type != null && type.IsArray)
+            if (type?.IsArray == true)
             {
                 type = type.GetElementType();
             }

src/ImageSharp/MetaData/Profiles/ICC/IccProfile.cs

@@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
     /// <summary>
     /// Represents an ICC profile
     /// </summary>
-    public sealed class IccProfile
+    public sealed class IccProfile : IDeepCloneable<IccProfile>
     {
         /// <summary>
         /// The byte array to read the ICC profile from
@@ -42,23 +42,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         /// Initializes a new instance of the <see cref="IccProfile"/> class.
         /// </summary>
         /// <param name="data">The raw ICC profile data</param>
-        public IccProfile(byte[] data)
-        {
-            this.data = data;
-        }
-
-        /// <summary>
-        /// Initializes a new instance of the <see cref="IccProfile"/> class
-        /// by making a copy from another ICC profile.
-        /// </summary>
-        /// <param name="other">The other ICC profile, where the clone should be made from.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="other"/> is null.</exception>>
-        public IccProfile(IccProfile other)
-        {
-            Guard.NotNull(other, nameof(other));
-
-            this.data = other.ToByteArray();
-        }
+        public IccProfile(byte[] data) => this.data = data;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IccProfile"/> class.
@@ -74,6 +58,19 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
             this.entries = new List<IccTagDataEntry>(entries);
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IccProfile"/> class
+        /// by making a copy from another ICC profile.
+        /// </summary>
+        /// <param name="other">The other ICC profile, where the clone should be made from.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="other"/> is null.</exception>>
+        private IccProfile(IccProfile other)
+        {
+            Guard.NotNull(other, nameof(other));
+
+            this.data = other.ToByteArray();
+        }
+
         /// <summary>
         /// Gets or sets the profile header
         /// </summary>
@@ -100,6 +97,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
             }
         }
 
+        /// <inheritdoc/>
+        public IccProfile DeepClone() => new IccProfile(this);
+
 #if !NETSTANDARD1_1
 
         /// <summary>

src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor.cs

@@ -2,10 +2,10 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Threading.Tasks;
+
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Processors;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Binarization
@@ -56,7 +56,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Binarization
         public TPixel LowerColor { get; set; }
 
         /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
+        protected override void OnFrameApply(
+            ImageFrame<TPixel> source,
+            Rectangle sourceRectangle,
+            Configuration configuration)
         {
             float threshold = this.Threshold * 255F;
             TPixel upper = this.UpperColor;
@@ -70,25 +73,29 @@ namespace SixLabors.ImageSharp.Processing.Processors.Binarization
 
             bool isAlphaOnly = typeof(TPixel) == typeof(Alpha8);
 
-            ParallelFor.WithConfiguration(
-                startY,
-                endY,
+            var workingRect = Rectangle.FromLTRB(startX, startY, endX, endY);
+
+            ParallelHelper.IterateRows(
+                workingRect,
                 configuration,
-                y =>
+                rows =>
                     {
-                        Span<TPixel> row = source.GetPixelRowSpan(y);
-                        Rgba32 rgba = default;
-
-                        for (int x = startX; x < endX; x++)
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            ref TPixel color = ref row[x];
-                            color.ToRgba32(ref rgba);
+                            Span<TPixel> row = source.GetPixelRowSpan(y);
+                            Rgba32 rgba = default;
+
+                            for (int x = startX; x < endX; x++)
+                            {
+                                ref TPixel color = ref row[x];
+                                color.ToRgba32(ref rgba);
 
-                            // Convert to grayscale using ITU-R Recommendation BT.709 if required
-                            float luminance = isAlphaOnly
-                                                  ? rgba.A
-                                                  : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B);
-                            color = luminance >= threshold ? upper : lower;
+                                // Convert to grayscale using ITU-R Recommendation BT.709 if required
+                                float luminance = isAlphaOnly
+                                                      ? rgba.A
+                                                      : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B);
+                                color = luminance >= threshold ? upper : lower;
+                            }
                         }
                     });
         }

src/ImageSharp/Processing/Processors/Convolution/Convolution2DProcessor.cs

@@ -3,12 +3,12 @@
 
 using System;
 using System.Numerics;
-using System.Threading.Tasks;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
-using SixLabors.Memory;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Convolution
@@ -42,7 +42,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
         public DenseMatrix<float> KernelY { get; }
 
         /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
+        protected override void OnFrameApply(
+            ImageFrame<TPixel> source,
+            Rectangle sourceRectangle,
+            Configuration configuration)
         {
             int kernelYHeight = this.KernelY.Rows;
             int kernelYWidth = this.KernelY.Columns;
@@ -58,71 +61,77 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
             int maxY = endY - 1;
             int maxX = endX - 1;
 
-            using (Buffer2D<TPixel> targetPixels = configuration.MemoryAllocator.Allocate2D<TPixel>(source.Width, source.Height))
+            using (Buffer2D<TPixel> targetPixels =
+                configuration.MemoryAllocator.Allocate2D<TPixel>(source.Width, source.Height))
             {
                 source.CopyTo(targetPixels);
 
-                ParallelFor.WithConfiguration(
-                    startY,
-                    endY,
-                    configuration,
-                    y =>
-                    {
-                        Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                        Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
+                var workingRectangle = Rectangle.FromLTRB(startX, startY, endX, endY);
 
-                        for (int x = startX; x < endX; x++)
+                ParallelHelper.IterateRows(
+                    workingRectangle,
+                    configuration,
+                    rows =>
                         {
-                            float rX = 0;
-                            float gX = 0;
-                            float bX = 0;
-                            float rY = 0;
-                            float gY = 0;
-                            float bY = 0;
-
-                            // Apply each matrix multiplier to the color components for each pixel.
-                            for (int fy = 0; fy < kernelYHeight; fy++)
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                int fyr = fy - radiusY;
-                                int offsetY = y + fyr;
+                                Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                                Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
 
-                                offsetY = offsetY.Clamp(0, maxY);
-                                Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
-
-                                for (int fx = 0; fx < kernelXWidth; fx++)
+                                for (int x = startX; x < endX; x++)
                                 {
-                                    int fxr = fx - radiusX;
-                                    int offsetX = x + fxr;
-
-                                    offsetX = offsetX.Clamp(0, maxX);
-                                    Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
-
-                                    if (fy < kernelXHeight)
+                                    float rX = 0;
+                                    float gX = 0;
+                                    float bX = 0;
+                                    float rY = 0;
+                                    float gY = 0;
+                                    float bY = 0;
+
+                                    // Apply each matrix multiplier to the color components for each pixel.
+                                    for (int fy = 0; fy < kernelYHeight; fy++)
                                     {
-                                        Vector4 kx = this.KernelX[fy, fx] * currentColor;
-                                        rX += kx.X;
-                                        gX += kx.Y;
-                                        bX += kx.Z;
+                                        int fyr = fy - radiusY;
+                                        int offsetY = y + fyr;
+
+                                        offsetY = offsetY.Clamp(0, maxY);
+                                        Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
+
+                                        for (int fx = 0; fx < kernelXWidth; fx++)
+                                        {
+                                            int fxr = fx - radiusX;
+                                            int offsetX = x + fxr;
+
+                                            offsetX = offsetX.Clamp(0, maxX);
+                                            Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
+
+                                            if (fy < kernelXHeight)
+                                            {
+                                                Vector4 kx = this.KernelX[fy, fx] * currentColor;
+                                                rX += kx.X;
+                                                gX += kx.Y;
+                                                bX += kx.Z;
+                                            }
+
+                                            if (fx < kernelYWidth)
+                                            {
+                                                Vector4 ky = this.KernelY[fy, fx] * currentColor;
+                                                rY += ky.X;
+                                                gY += ky.Y;
+                                                bY += ky.Z;
+                                            }
+                                        }
                                     }
 
-                                    if (fx < kernelYWidth)
-                                    {
-                                        Vector4 ky = this.KernelY[fy, fx] * currentColor;
-                                        rY += ky.X;
-                                        gY += ky.Y;
-                                        bY += ky.Z;
-                                    }
+                                    float red = MathF.Sqrt((rX * rX) + (rY * rY));
+                                    float green = MathF.Sqrt((gX * gX) + (gY * gY));
+                                    float blue = MathF.Sqrt((bX * bX) + (bY * bY));
+
+                                    ref TPixel pixel = ref targetRow[x];
+                                    pixel.PackFromVector4(
+                                        new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
                                 }
                             }
-
-                            float red = MathF.Sqrt((rX * rX) + (rY * rY));
-                            float green = MathF.Sqrt((gX * gX) + (gY * gY));
-                            float blue = MathF.Sqrt((bX * bX) + (bY * bY));
-
-                            ref TPixel pixel = ref targetRow[x];
-                            pixel.PackFromVector4(new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
-                        }
-                    });
+                        });
 
                 Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
             }

src/ImageSharp/Processing/Processors/Convolution/Convolution2PassProcessor.cs

@@ -6,6 +6,7 @@ using System.Numerics;
 using System.Threading.Tasks;
 
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.ImageSharp.Processing.Processors;
@@ -82,43 +83,47 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
             int maxY = endY - 1;
             int maxX = endX - 1;
 
-            ParallelFor.WithConfiguration(
-                startY,
-                endY,
-                configuration,
-                y =>
-                {
-                    Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
+            var workingRectangle = Rectangle.FromLTRB(startX, startY, endX, endY);
 
-                    for (int x = startX; x < endX; x++)
+            ParallelHelper.IterateRows(
+                workingRectangle,
+                configuration,
+                rows =>
                     {
-                        Vector4 destination = default;
-
-                        // Apply each matrix multiplier to the color components for each pixel.
-                        for (int fy = 0; fy < kernelHeight; fy++)
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            int fyr = fy - radiusY;
-                            int offsetY = y + fyr;
+                            Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
 
-                            offsetY = offsetY.Clamp(0, maxY);
-                            Span<TPixel> row = sourcePixels.GetRowSpan(offsetY);
-
-                            for (int fx = 0; fx < kernelWidth; fx++)
+                            for (int x = startX; x < endX; x++)
                             {
-                                int fxr = fx - radiusX;
-                                int offsetX = x + fxr;
+                                Vector4 destination = default;
+
+                                // Apply each matrix multiplier to the color components for each pixel.
+                                for (int fy = 0; fy < kernelHeight; fy++)
+                                {
+                                    int fyr = fy - radiusY;
+                                    int offsetY = y + fyr;
 
-                                offsetX = offsetX.Clamp(0, maxX);
+                                    offsetY = offsetY.Clamp(0, maxY);
+                                    Span<TPixel> row = sourcePixels.GetRowSpan(offsetY);
 
-                                Vector4 currentColor = row[offsetX].ToVector4().Premultiply();
-                                destination += kernel[fy, fx] * currentColor;
+                                    for (int fx = 0; fx < kernelWidth; fx++)
+                                    {
+                                        int fxr = fx - radiusX;
+                                        int offsetX = x + fxr;
+
+                                        offsetX = offsetX.Clamp(0, maxX);
+
+                                        Vector4 currentColor = row[offsetX].ToVector4().Premultiply();
+                                        destination += kernel[fy, fx] * currentColor;
+                                    }
+                                }
+
+                                ref TPixel pixel = ref targetRow[x];
+                                pixel.PackFromVector4(destination.UnPremultiply());
                             }
                         }
-
-                        ref TPixel pixel = ref targetRow[x];
-                        pixel.PackFromVector4(destination.UnPremultiply());
-                    }
-                });
+                    });
         }
     }
 }

src/ImageSharp/Processing/Processors/Convolution/ConvolutionProcessor.cs

@@ -6,6 +6,7 @@ using System.Numerics;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.ImageSharp.Processing.Processors;
@@ -52,50 +53,55 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
             {
                 source.CopyTo(targetPixels);
 
-                ParallelFor.WithConfiguration(
-                 startY,
-                 endY,
-                 configuration,
-                 y =>
-                 {
-                     Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                     Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
-
-                     for (int x = startX; x < endX; x++)
-                     {
-                         float red = 0;
-                         float green = 0;
-                         float blue = 0;
-
-                         // Apply each matrix multiplier to the color components for each pixel.
-                         for (int fy = 0; fy < kernelLength; fy++)
-                         {
-                             int fyr = fy - radius;
-                             int offsetY = y + fyr;
-
-                             offsetY = offsetY.Clamp(0, maxY);
-                             Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
-
-                             for (int fx = 0; fx < kernelLength; fx++)
-                             {
-                                 int fxr = fx - radius;
-                                 int offsetX = x + fxr;
-
-                                 offsetX = offsetX.Clamp(0, maxX);
-
-                                 Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
-                                 currentColor *= this.KernelXY[fy, fx];
-
-                                 red += currentColor.X;
-                                 green += currentColor.Y;
-                                 blue += currentColor.Z;
-                             }
-                         }
-
-                         ref TPixel pixel = ref targetRow[x];
-                         pixel.PackFromVector4(new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
-                     }
-                 });
+                var workingRect = Rectangle.FromLTRB(startX, startY, endX, endY);
+
+                ParallelHelper.IterateRows(
+                    workingRect,
+                    configuration,
+                    rows =>
+                        {
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                                Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
+
+                                for (int x = startX; x < endX; x++)
+                                {
+                                    float red = 0;
+                                    float green = 0;
+                                    float blue = 0;
+
+                                    // Apply each matrix multiplier to the color components for each pixel.
+                                    for (int fy = 0; fy < kernelLength; fy++)
+                                    {
+                                        int fyr = fy - radius;
+                                        int offsetY = y + fyr;
+
+                                        offsetY = offsetY.Clamp(0, maxY);
+                                        Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
+
+                                        for (int fx = 0; fx < kernelLength; fx++)
+                                        {
+                                            int fxr = fx - radius;
+                                            int offsetX = x + fxr;
+
+                                            offsetX = offsetX.Clamp(0, maxX);
+
+                                            Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
+                                            currentColor *= this.KernelXY[fy, fx];
+
+                                            red += currentColor.X;
+                                            green += currentColor.Y;
+                                            blue += currentColor.Z;
+                                        }
+                                    }
+
+                                    ref TPixel pixel = ref targetRow[x];
+                                    pixel.PackFromVector4(
+                                        new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
+                                }
+                            }
+                        });
 
                 Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
             }

src/ImageSharp/Processing/Processors/Convolution/EdgeDetectorCompassProcessor.cs

@@ -8,6 +8,7 @@ using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.ImageSharp.Processing.Processors.Filters;
@@ -124,6 +125,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
                     shiftY = 0;
                 }
 
+                var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
                 // Additional runs.
                 // ReSharper disable once ForCanBeConvertedToForeach
                 for (int i = 1; i < kernels.Length; i++)
@@ -135,30 +138,35 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
                         Buffer2D<TPixel> passPixels = pass.PixelBuffer;
                         Buffer2D<TPixel> targetPixels = source.PixelBuffer;
 
-                        ParallelFor.WithConfiguration(
-                            minY,
-                            maxY,
+                        ParallelHelper.IterateRows(
+                            workingRect,
                             configuration,
-                            y =>
+                            rows =>
                                 {
-                                    int offsetY = y - shiftY;
+                                    for (int y = rows.Min; y < rows.Max; y++)
+                                    {
+                                        int offsetY = y - shiftY;
 
-                                    ref TPixel passPixelsBase = ref MemoryMarshal.GetReference(passPixels.GetRowSpan(offsetY));
-                                    ref TPixel targetPixelsBase = ref MemoryMarshal.GetReference(targetPixels.GetRowSpan(offsetY));
+                                        ref TPixel passPixelsBase =
+                                            ref MemoryMarshal.GetReference(passPixels.GetRowSpan(offsetY));
+                                        ref TPixel targetPixelsBase =
+                                            ref MemoryMarshal.GetReference(targetPixels.GetRowSpan(offsetY));
 
-                                    for (int x = minX; x < maxX; x++)
-                                    {
-                                        int offsetX = x - shiftX;
+                                        for (int x = minX; x < maxX; x++)
+                                        {
+                                            int offsetX = x - shiftX;
 
-                                        // Grab the max components of the two pixels
-                                        ref TPixel currentPassPixel = ref Unsafe.Add(ref passPixelsBase, offsetX);
-                                        ref TPixel currentTargetPixel = ref Unsafe.Add(ref targetPixelsBase, offsetX);
+                                            // Grab the max components of the two pixels
+                                            ref TPixel currentPassPixel = ref Unsafe.Add(ref passPixelsBase, offsetX);
+                                            ref TPixel currentTargetPixel =
+                                                ref Unsafe.Add(ref targetPixelsBase, offsetX);
 
-                                        var pixelValue = Vector4.Max(
-                                            currentPassPixel.ToVector4(),
-                                            currentTargetPixel.ToVector4());
+                                            var pixelValue = Vector4.Max(
+                                                currentPassPixel.ToVector4(),
+                                                currentTargetPixel.ToVector4());
 
-                                        currentTargetPixel.PackFromVector4(pixelValue);
+                                            currentTargetPixel.PackFromVector4(pixelValue);
+                                        }
                                     }
                                 });
                     }

src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor.cs

@@ -3,11 +3,11 @@
 
 using System;
 using System.Numerics;
-using System.Threading.Tasks;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Memory;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Effects
@@ -49,7 +49,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         public int BrushSize { get; }
 
         /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
+        protected override void OnFrameApply(
+            ImageFrame<TPixel> source,
+            Rectangle sourceRectangle,
+            Configuration configuration)
         {
             if (this.BrushSize <= 0 || this.BrushSize > source.Height || this.BrushSize > source.Width)
             {
@@ -70,69 +73,74 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
             {
                 source.CopyTo(targetPixels);
 
-                ParallelFor.WithConfiguration(
-                    startY,
-                    maxY,
+                var workingRect = Rectangle.FromLTRB(startX, startY, endX, endY);
+                ParallelHelper.IterateRows(
+                    workingRect,
                     configuration,
-                    y =>
-                    {
-                        Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                        Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
-
-                        for (int x = startX; x < endX; x++)
+                    rows =>
                         {
-                            int maxIntensity = 0;
-                            int maxIndex = 0;
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                                Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
 
-                            int[] intensityBin = new int[levels];
-                            float[] redBin = new float[levels];
-                            float[] blueBin = new float[levels];
-                            float[] greenBin = new float[levels];
+                                for (int x = startX; x < endX; x++)
+                                {
+                                    int maxIntensity = 0;
+                                    int maxIndex = 0;
 
-                            for (int fy = 0; fy <= radius; fy++)
-                            {
-                                int fyr = fy - radius;
-                                int offsetY = y + fyr;
+                                    int[] intensityBin = new int[levels];
+                                    float[] redBin = new float[levels];
+                                    float[] blueBin = new float[levels];
+                                    float[] greenBin = new float[levels];
 
-                                offsetY = offsetY.Clamp(0, maxY);
+                                    for (int fy = 0; fy <= radius; fy++)
+                                    {
+                                        int fyr = fy - radius;
+                                        int offsetY = y + fyr;
 
-                                Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
+                                        offsetY = offsetY.Clamp(0, maxY);
 
-                                for (int fx = 0; fx <= radius; fx++)
-                                {
-                                    int fxr = fx - radius;
-                                    int offsetX = x + fxr;
-                                    offsetX = offsetX.Clamp(0, maxX);
+                                        Span<TPixel> sourceOffsetRow = source.GetPixelRowSpan(offsetY);
 
-                                    var vector = sourceOffsetRow[offsetX].ToVector4();
+                                        for (int fx = 0; fx <= radius; fx++)
+                                        {
+                                            int fxr = fx - radius;
+                                            int offsetX = x + fxr;
+                                            offsetX = offsetX.Clamp(0, maxX);
 
-                                    float sourceRed = vector.X;
-                                    float sourceBlue = vector.Z;
-                                    float sourceGreen = vector.Y;
+                                            var vector = sourceOffsetRow[offsetX].ToVector4();
 
-                                    int currentIntensity = (int)MathF.Round((sourceBlue + sourceGreen + sourceRed) / 3F * (levels - 1));
+                                            float sourceRed = vector.X;
+                                            float sourceBlue = vector.Z;
+                                            float sourceGreen = vector.Y;
 
-                                    intensityBin[currentIntensity]++;
-                                    blueBin[currentIntensity] += sourceBlue;
-                                    greenBin[currentIntensity] += sourceGreen;
-                                    redBin[currentIntensity] += sourceRed;
+                                            int currentIntensity = (int)MathF.Round(
+                                                (sourceBlue + sourceGreen + sourceRed) / 3F * (levels - 1));
 
-                                    if (intensityBin[currentIntensity] > maxIntensity)
-                                    {
-                                        maxIntensity = intensityBin[currentIntensity];
-                                        maxIndex = currentIntensity;
-                                    }
-                                }
+                                            intensityBin[currentIntensity]++;
+                                            blueBin[currentIntensity] += sourceBlue;
+                                            greenBin[currentIntensity] += sourceGreen;
+                                            redBin[currentIntensity] += sourceRed;
 
-                                float red = MathF.Abs(redBin[maxIndex] / maxIntensity);
-                                float green = MathF.Abs(greenBin[maxIndex] / maxIntensity);
-                                float blue = MathF.Abs(blueBin[maxIndex] / maxIntensity);
+                                            if (intensityBin[currentIntensity] > maxIntensity)
+                                            {
+                                                maxIntensity = intensityBin[currentIntensity];
+                                                maxIndex = currentIntensity;
+                                            }
+                                        }
 
-                                ref TPixel pixel = ref targetRow[x];
-                                pixel.PackFromVector4(new Vector4(red, green, blue, sourceRow[x].ToVector4().W));
+                                        float red = MathF.Abs(redBin[maxIndex] / maxIntensity);
+                                        float green = MathF.Abs(greenBin[maxIndex] / maxIntensity);
+                                        float blue = MathF.Abs(blueBin[maxIndex] / maxIntensity);
+
+                                        ref TPixel pixel = ref targetRow[x];
+                                        pixel.PackFromVector4(
+                                            new Vector4(red, green, blue, sourceRow[x].ToVector4().W));
+                                    }
+                                }
                             }
-                        }
-                    });
+                        });
 
                 Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
             }

src/ImageSharp/Processing/Processors/Filters/FilterProcessor.cs

@@ -5,6 +5,7 @@ using System;
 using System.Numerics;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
@@ -35,25 +36,24 @@ namespace SixLabors.ImageSharp.Processing.Processors.Filters
         protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
         {
             var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
-            int startY = interest.Y;
-            int endY = interest.Bottom;
-            int startX = interest.X;
-            int endX = interest.Right;
+
             Matrix4x4 matrix = this.Matrix;
 
-            ParallelFor.WithConfiguration(
-                startY,
-                endY,
+            ParallelHelper.IterateRows(
+                interest,
                 configuration,
-                y =>
+                rows =>
                     {
-                        Span<TPixel> row = source.GetPixelRowSpan(y);
-
-                        for (int x = startX; x < endX; x++)
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            ref TPixel pixel = ref row[x];
-                            var vector = Vector4.Transform(pixel.ToVector4(), matrix);
-                            pixel.PackFromVector4(vector);
+                            Span<TPixel> row = source.GetPixelRowSpan(y);
+
+                            for (int x = interest.X; x < interest.Right; x++)
+                            {
+                                ref TPixel pixel = ref row[x];
+                                var vector = Vector4.Transform(pixel.ToVector4(), matrix);
+                                pixel.PackFromVector4(vector);
+                            }
                         }
                     });
         }

src/ImageSharp/Processing/Processors/Overlays/BackgroundColorProcessor.cs

@@ -6,6 +6,7 @@ using System.Buffers;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -67,6 +68,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Overlays
 
             int width = maxX - minX;
 
+            var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
             using (IMemoryOwner<TPixel> colors = source.MemoryAllocator.Allocate<TPixel>(width))
             using (IMemoryOwner<float> amount = source.MemoryAllocator.Allocate<float>(width))
             {
@@ -74,25 +77,30 @@ namespace SixLabors.ImageSharp.Processing.Processors.Overlays
                 Span<TPixel> colorSpan = colors.GetSpan();
                 Span<float> amountSpan = amount.GetSpan();
 
-                // TODO: Use Span.Fill?
-                for (int i = 0; i < width; i++)
-                {
-                    colorSpan[i] = this.Color;
-                    amountSpan[i] = this.GraphicsOptions.BlendPercentage;
-                }
+                colorSpan.Fill(this.Color);
+                amountSpan.Fill(this.GraphicsOptions.BlendPercentage);
 
                 PixelBlender<TPixel> blender = PixelOperations<TPixel>.Instance.GetPixelBlender(this.GraphicsOptions);
-                ParallelFor.WithConfiguration(
-                    minY,
-                    maxY,
+
+                ParallelHelper.IterateRows(
+                    workingRect,
                     configuration,
-                    y =>
-                    {
-                        Span<TPixel> destination = source.GetPixelRowSpan(y - startY).Slice(minX - startX, width);
+                    rows =>
+                        {
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                Span<TPixel> destination =
+                                    source.GetPixelRowSpan(y - startY).Slice(minX - startX, width);
 
-                        // This switched color & destination in the 2nd and 3rd places because we are applying the target color under the current one
-                        blender.Blend(source.MemoryAllocator, destination, colors.GetSpan(), destination, amount.GetSpan());
-                    });
+                                // This switched color & destination in the 2nd and 3rd places because we are applying the target color under the current one
+                                blender.Blend(
+                                    source.MemoryAllocator,
+                                    destination,
+                                    colors.GetSpan(),
+                                    destination,
+                                    amount.GetSpan());
+                            }
+                        });
             }
         }
     }

src/ImageSharp/Processing/Processors/Overlays/GlowProcessor.cs

@@ -7,6 +7,7 @@ using System.Numerics;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Memory;
@@ -84,6 +85,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Overlays
         /// <inheritdoc/>
         protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration)
         {
+            // TODO: can we simplify the rectangle calculation?
             int startY = sourceRectangle.Y;
             int endY = sourceRectangle.Bottom;
             int startX = sourceRectangle.X;
@@ -113,36 +115,43 @@ namespace SixLabors.ImageSharp.Processing.Processors.Overlays
             }
 
             int width = maxX - minX;
+            int offsetX = minX - startX;
+
+            var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
             using (IMemoryOwner<TPixel> rowColors = source.MemoryAllocator.Allocate<TPixel>(width))
             {
-                // Be careful! Do not capture rowColorsSpan in the lambda below!
-                Span<TPixel> rowColorsSpan = rowColors.GetSpan();
-
-                for (int i = 0; i < width; i++)
-                {
-                    rowColorsSpan[i] = glowColor;
-                }
+                rowColors.GetSpan().Fill(glowColor);
 
-                ParallelFor.WithTemporaryBuffer<float>(
-                    minY,
-                    maxY,
+                ParallelHelper.IterateRowsWithTempBuffer<float>(
+                    workingRect,
                     configuration,
-                    width,
-                    (y, amounts) =>
-                    {
-                        Span<float> amountsSpan = amounts.GetSpan();
-                        int offsetY = y - startY;
-                        int offsetX = minX - startX;
-                        for (int i = 0; i < width; i++)
+                    (rows, amounts) =>
                         {
-                            float distance = Vector2.Distance(center, new Vector2(i + offsetX, offsetY));
-                            amountsSpan[i] = (this.GraphicsOptions.BlendPercentage * (1 - (.95F * (distance / maxDistance)))).Clamp(0, 1);
-                        }
-
-                        Span<TPixel> destination = source.GetPixelRowSpan(offsetY).Slice(offsetX, width);
-
-                        this.blender.Blend(source.MemoryAllocator, destination, destination, rowColors.GetSpan(), amountsSpan);
-                    });
+                            Span<float> amountsSpan = amounts.Span;
+
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                int offsetY = y - startY;
+
+                                for (int i = 0; i < width; i++)
+                                {
+                                    float distance = Vector2.Distance(center, new Vector2(i + offsetX, offsetY));
+                                    amountsSpan[i] =
+                                        (this.GraphicsOptions.BlendPercentage * (1 - (.95F * (distance / maxDistance))))
+                                        .Clamp(0, 1);
+                                }
+
+                                Span<TPixel> destination = source.GetPixelRowSpan(offsetY).Slice(offsetX, width);
+
+                                this.blender.Blend(
+                                    source.MemoryAllocator,
+                                    destination,
+                                    destination,
+                                    rowColors.GetSpan(),
+                                    amountsSpan);
+                            }
+                        });
             }
         }
     }

src/ImageSharp/Processing/Processors/Overlays/VignetteProcessor.cs

@@ -7,6 +7,7 @@ using System.Numerics;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Memory;
@@ -115,43 +116,43 @@ namespace SixLabors.ImageSharp.Processing.Processors.Overlays
             }
 
             int width = maxX - minX;
+            int offsetX = minX - startX;
+
+            var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
             using (IMemoryOwner<TPixel> rowColors = source.MemoryAllocator.Allocate<TPixel>(width))
             {
-                // Be careful! Do not capture rowColorsSpan in the lambda below!
-                Span<TPixel> rowColorsSpan = rowColors.GetSpan();
-
-                for (int i = 0; i < width; i++)
-                {
-                    rowColorsSpan[i] = vignetteColor;
-                }
+                rowColors.GetSpan().Fill(vignetteColor);
 
-                ParallelFor.WithTemporaryBuffer<float>(
-                    minY,
-                    maxY,
+                ParallelHelper.IterateRowsWithTempBuffer<float>(
+                    workingRect,
                     configuration,
-                    width,
-                    (y, amounts) =>
+                    (rows, amounts) =>
                         {
-                            Span<float> amountsSpan = amounts.GetSpan();
-                            int offsetY = y - startY;
-                            int offsetX = minX - startX;
-                            for (int i = 0; i < width; i++)
+                            Span<float> amountsSpan = amounts.Span;
+
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                float distance = Vector2.Distance(centre, new Vector2(i + offsetX, offsetY));
-                                amountsSpan[i] =
-                                    (this.GraphicsOptions.BlendPercentage * (.9F * (distance / maxDistance))).Clamp(
-                                        0,
-                                        1);
+                                int offsetY = y - startY;
+
+                                for (int i = 0; i < width; i++)
+                                {
+                                    float distance = Vector2.Distance(centre, new Vector2(i + offsetX, offsetY));
+                                    amountsSpan[i] =
+                                        (this.GraphicsOptions.BlendPercentage * (.9F * (distance / maxDistance))).Clamp(
+                                            0,
+                                            1);
+                                }
+
+                                Span<TPixel> destination = source.GetPixelRowSpan(offsetY).Slice(offsetX, width);
+
+                                this.blender.Blend(
+                                    source.MemoryAllocator,
+                                    destination,
+                                    destination,
+                                    rowColors.GetSpan(),
+                                    amountsSpan);
                             }
-
-                            Span<TPixel> destination = source.GetPixelRowSpan(offsetY).Slice(offsetX, width);
-
-                            this.blender.Blend(
-                                source.MemoryAllocator,
-                                destination,
-                                destination,
-                                rowColors.GetSpan(),
-                                amountsSpan);
                         });
             }
         }

src/ImageSharp/Processing/Processors/Quantization/QuantizedFrame{TPixel}.cs

@@ -3,7 +3,7 @@
 
 using System;
 using System.Buffers;
-
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
@@ -57,8 +57,18 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         /// Gets the pixels of this <see cref="QuantizedFrame{TPixel}"/>.
         /// </summary>
         /// <returns>The <see cref="Span{T}"/></returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
         public Span<byte> GetPixelSpan() => this.pixels.GetSpan();
 
+        /// <summary>
+        /// Gets the representation of the pixels as a <see cref="Span{T}"/> of contiguous memory
+        /// at row <paramref name="rowIndex"/> beginning from the the first pixel on that row.
+        /// </summary>
+        /// <param name="rowIndex">The row.</param>
+        /// <returns>The <see cref="Span{T}"/></returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public Span<byte> GetRowSpan(int rowIndex) => this.GetPixelSpan().Slice(rowIndex * this.Width, this.Width);
+
         /// <inheritdoc/>
         public void Dispose()
         {

src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor.cs

@@ -10,6 +10,7 @@ using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -51,10 +52,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
             IEnumerable<ImageFrame<TPixel>> frames =
-                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions, x.MetaData.Clone()));
+                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
-            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);
+            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.DeepClone(), frames);
         }
 
         /// <inheritdoc/>
@@ -78,23 +79,25 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
             if (this.Sampler is NearestNeighborResampler)
             {
-                ParallelFor.WithConfiguration(
-                    0,
-                    height,
+                ParallelHelper.IterateRows(
+                    targetBounds,
                     configuration,
-                    y =>
-                    {
-                        Span<TPixel> destRow = destination.GetPixelRowSpan(y);
-
-                        for (int x = 0; x < width; x++)
+                    rows =>
                         {
-                            var point = Point.Transform(new Point(x, y), matrix);
-                            if (sourceBounds.Contains(point.X, point.Y))
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                destRow[x] = source[point.X, point.Y];
+                                Span<TPixel> destRow = destination.GetPixelRowSpan(y);
+
+                                for (int x = 0; x < width; x++)
+                                {
+                                    var point = Point.Transform(new Point(x, y), matrix);
+                                    if (sourceBounds.Contains(point.X, point.Y))
+                                    {
+                                        destRow[x] = source[point.X, point.Y];
+                                    }
+                                }
                             }
-                        }
-                    });
+                        });
 
                 return;
             }
@@ -116,86 +119,107 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             using (Buffer2D<float> yBuffer = memoryAllocator.Allocate2D<float>(yLength, height))
             using (Buffer2D<float> xBuffer = memoryAllocator.Allocate2D<float>(xLength, height))
             {
-                ParallelFor.WithConfiguration(
-                    0,
-                    height,
+                ParallelHelper.IterateRows(
+                    targetBounds,
                     configuration,
-                    y =>
+                    rows =>
                         {
-                            ref TPixel destRowRef = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
-                            ref float ySpanRef = ref MemoryMarshal.GetReference(yBuffer.GetRowSpan(y));
-                            ref float xSpanRef = ref MemoryMarshal.GetReference(xBuffer.GetRowSpan(y));
-
-                            for (int x = 0; x < width; x++)
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                // Use the single precision position to calculate correct bounding pixels
-                                // otherwise we get rogue pixels outside of the bounds.
-                                var point = Vector2.Transform(new Vector2(x, y), matrix);
-
-                                // Clamp sampling pixel radial extents to the source image edges
-                                Vector2 maxXY = point + radius;
-                                Vector2 minXY = point - radius;
-
-                                // max, maxY, minX, minY
-                                var extents = new Vector4(
-                                    MathF.Floor(maxXY.X + .5F),
-                                    MathF.Floor(maxXY.Y + .5F),
-                                    MathF.Ceiling(minXY.X - .5F),
-                                    MathF.Ceiling(minXY.Y - .5F));
-
-                                int right = (int)extents.X;
-                                int bottom = (int)extents.Y;
-                                int left = (int)extents.Z;
-                                int top = (int)extents.W;
-
-                                extents = Vector4.Clamp(extents, Vector4.Zero, maxSource);
-
-                                int maxX = (int)extents.X;
-                                int maxY = (int)extents.Y;
-                                int minX = (int)extents.Z;
-                                int minY = (int)extents.W;
-
-                                if (minX == maxX || minY == maxY)
-                                {
-                                    continue;
-                                }
+                                ref TPixel destRowRef = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
+                                ref float ySpanRef = ref MemoryMarshal.GetReference(yBuffer.GetRowSpan(y));
+                                ref float xSpanRef = ref MemoryMarshal.GetReference(xBuffer.GetRowSpan(y));
 
-                                // It appears these have to be calculated on-the-fly.
-                                // Precalulating transformed weights would require prior knowledge of every transformed pixel location
-                                // since they can be at sub-pixel positions on both axis.
-                                // I've optimized where I can but am always open to suggestions.
-                                if (yScale > 1 && xScale > 1)
-                                {
-                                    CalculateWeightsDown(top, bottom, minY, maxY, point.Y, sampler, yScale, ref ySpanRef, yLength);
-                                    CalculateWeightsDown(left, right, minX, maxX, point.X, sampler, xScale, ref xSpanRef, xLength);
-                                }
-                                else
+                                for (int x = 0; x < width; x++)
                                 {
-                                    CalculateWeightsScaleUp(minY, maxY, point.Y, sampler, ref ySpanRef);
-                                    CalculateWeightsScaleUp(minX, maxX, point.X, sampler, ref xSpanRef);
-                                }
+                                    // Use the single precision position to calculate correct bounding pixels
+                                    // otherwise we get rogue pixels outside of the bounds.
+                                    var point = Vector2.Transform(new Vector2(x, y), matrix);
+
+                                    // Clamp sampling pixel radial extents to the source image edges
+                                    Vector2 maxXY = point + radius;
+                                    Vector2 minXY = point - radius;
+
+                                    // max, maxY, minX, minY
+                                    var extents = new Vector4(
+                                        MathF.Floor(maxXY.X + .5F),
+                                        MathF.Floor(maxXY.Y + .5F),
+                                        MathF.Ceiling(minXY.X - .5F),
+                                        MathF.Ceiling(minXY.Y - .5F));
+
+                                    int right = (int)extents.X;
+                                    int bottom = (int)extents.Y;
+                                    int left = (int)extents.Z;
+                                    int top = (int)extents.W;
+
+                                    extents = Vector4.Clamp(extents, Vector4.Zero, maxSource);
+
+                                    int maxX = (int)extents.X;
+                                    int maxY = (int)extents.Y;
+                                    int minX = (int)extents.Z;
+                                    int minY = (int)extents.W;
+
+                                    if (minX == maxX || minY == maxY)
+                                    {
+                                        continue;
+                                    }
 
-                                // Now multiply the results against the offsets
-                                Vector4 sum = Vector4.Zero;
-                                for (int yy = 0, j = minY; j <= maxY; j++, yy++)
-                                {
-                                    float yWeight = Unsafe.Add(ref ySpanRef, yy);
+                                    // It appears these have to be calculated on-the-fly.
+                                    // Precalculating transformed weights would require prior knowledge of every transformed pixel location
+                                    // since they can be at sub-pixel positions on both axis.
+                                    // I've optimized where I can but am always open to suggestions.
+                                    if (yScale > 1 && xScale > 1)
+                                    {
+                                        CalculateWeightsDown(
+                                            top,
+                                            bottom,
+                                            minY,
+                                            maxY,
+                                            point.Y,
+                                            sampler,
+                                            yScale,
+                                            ref ySpanRef,
+                                            yLength);
+
+                                        CalculateWeightsDown(
+                                            left,
+                                            right,
+                                            minX,
+                                            maxX,
+                                            point.X,
+                                            sampler,
+                                            xScale,
+                                            ref xSpanRef,
+                                            xLength);
+                                    }
+                                    else
+                                    {
+                                        CalculateWeightsScaleUp(minY, maxY, point.Y, sampler, ref ySpanRef);
+                                        CalculateWeightsScaleUp(minX, maxX, point.X, sampler, ref xSpanRef);
+                                    }
 
-                                    for (int xx = 0, i = minX; i <= maxX; i++, xx++)
+                                    // Now multiply the results against the offsets
+                                    Vector4 sum = Vector4.Zero;
+                                    for (int yy = 0, j = minY; j <= maxY; j++, yy++)
                                     {
-                                        float xWeight = Unsafe.Add(ref xSpanRef, xx);
-                                        var vector = source[i, j].ToVector4();
+                                        float yWeight = Unsafe.Add(ref ySpanRef, yy);
+
+                                        for (int xx = 0, i = minX; i <= maxX; i++, xx++)
+                                        {
+                                            float xWeight = Unsafe.Add(ref xSpanRef, xx);
+                                            var vector = source[i, j].ToVector4();
 
-                                        // Values are first premultiplied to prevent darkening of edge pixels
-                                        Vector4 multiplied = vector.Premultiply();
-                                        sum += multiplied * xWeight * yWeight;
+                                            // Values are first premultiplied to prevent darkening of edge pixels
+                                            Vector4 multiplied = vector.Premultiply();
+                                            sum += multiplied * xWeight * yWeight;
+                                        }
                                     }
-                                }
 
-                                ref TPixel dest = ref Unsafe.Add(ref destRowRef, x);
+                                    ref TPixel dest = ref Unsafe.Add(ref destRowRef, x);
 
-                                // Reverse the premultiplication
-                                dest.PackFromVector4(sum.UnPremultiply());
+                                    // Reverse the premultiplication
+                                    dest.PackFromVector4(sum.UnPremultiply());
+                                }
                             }
                         });
             }

src/ImageSharp/Processing/Processors/Transforms/CropProcessor.cs

@@ -4,8 +4,8 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
@@ -36,10 +36,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         protected override Image<TPixel> CreateDestination(Image<TPixel> source, Rectangle sourceRectangle)
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
-            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.CropRectangle.Width, this.CropRectangle.Height, x.MetaData.Clone()));
+            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.CropRectangle.Width, this.CropRectangle.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
-            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);
+            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.DeepClone(), frames);
         }
 
         /// <inheritdoc/>
@@ -53,21 +53,23 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 return;
             }
 
-            int minY = Math.Max(this.CropRectangle.Y, sourceRectangle.Y);
-            int maxY = Math.Min(this.CropRectangle.Bottom, sourceRectangle.Bottom);
-            int minX = Math.Max(this.CropRectangle.X, sourceRectangle.X);
-            int maxX = Math.Min(this.CropRectangle.Right, sourceRectangle.Right);
+            var rect = Rectangle.Intersect(this.CropRectangle, sourceRectangle);
 
-            ParallelFor.WithConfiguration(
-                minY,
-                maxY,
-                configuration,
-                y =>
-                {
-                    Span<TPixel> sourceRow = source.GetPixelRowSpan(y).Slice(minX);
-                    Span<TPixel> targetRow = destination.GetPixelRowSpan(y - minY);
-                    sourceRow.Slice(0, maxX - minX).CopyTo(targetRow);
-                });
+            // Copying is cheap, we should process more pixels per task:
+            ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings().MultiplyMinimumPixelsPerTask(4);
+
+            ParallelHelper.IterateRows(
+                rect,
+                parallelSettings,
+                rows =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y).Slice(rect.Left);
+                            Span<TPixel> targetRow = destination.GetPixelRowSpan(y - rect.Top);
+                            sourceRow.Slice(0, rect.Width).CopyTo(targetRow);
+                        }
+                    });
         }
     }
 }

src/ImageSharp/Processing/Processors/Transforms/FlipProcessor.cs

@@ -2,9 +2,11 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Buffers;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -55,27 +57,20 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         private void FlipX(ImageFrame<TPixel> source, Configuration configuration)
         {
             int height = source.Height;
-            int halfHeight = (int)Math.Ceiling(source.Height * .5F);
 
-            using (Buffer2D<TPixel> targetPixels = configuration.MemoryAllocator.Allocate2D<TPixel>(source.Size()))
+            using (IMemoryOwner<TPixel> tempBuffer = configuration.MemoryAllocator.Allocate<TPixel>(source.Width))
             {
-                ParallelFor.WithConfiguration(
-                    0,
-                    halfHeight,
-                    configuration,
-                    y =>
-                        {
-                            int newY = height - y - 1;
-                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                            Span<TPixel> altSourceRow = source.GetPixelRowSpan(newY);
-                            Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
-                            Span<TPixel> altTargetRow = targetPixels.GetRowSpan(newY);
-
-                            sourceRow.CopyTo(altTargetRow);
-                            altSourceRow.CopyTo(targetRow);
-                        });
+                Span<TPixel> temp = tempBuffer.Memory.Span;
 
-                Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
+                for (int yTop = 0; yTop < height / 2; yTop++)
+                {
+                    int yBottom = height - yTop - 1;
+                    Span<TPixel> topRow = source.GetPixelRowSpan(yBottom);
+                    Span<TPixel> bottomRow = source.GetPixelRowSpan(yTop);
+                    topRow.CopyTo(temp);
+                    bottomRow.CopyTo(topRow);
+                    temp.CopyTo(bottomRow);
+                }
             }
         }
 
@@ -86,31 +81,16 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         /// <param name="configuration">The configuration.</param>
         private void FlipY(ImageFrame<TPixel> source, Configuration configuration)
         {
-            int width = source.Width;
-            int height = source.Height;
-            int halfWidth = (int)Math.Ceiling(width * .5F);
-
-            using (Buffer2D<TPixel> targetPixels = configuration.MemoryAllocator.Allocate2D<TPixel>(source.Size()))
-            {
-                ParallelFor.WithConfiguration(
-                    0,
-                    height,
-                    configuration,
-                    y =>
+            ParallelHelper.IterateRows(
+                source.Bounds(),
+                configuration,
+                rows =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                            Span<TPixel> targetRow = targetPixels.GetRowSpan(y);
-
-                            for (int x = 0; x < halfWidth; x++)
-                            {
-                                int newX = width - x - 1;
-                                targetRow[x] = sourceRow[newX];
-                                targetRow[newX] = sourceRow[x];
-                            }
-                        });
-
-                Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
-            }
+                            source.GetPixelRowSpan(y).Reverse();
+                        }
+                    });
         }
     }
 }

src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor.cs

@@ -10,6 +10,7 @@ using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -51,10 +52,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
             IEnumerable<ImageFrame<TPixel>> frames =
-                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions.Width, this.TargetDimensions.Height, x.MetaData.Clone()));
+                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions.Width, this.TargetDimensions.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
-            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);
+            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.DeepClone(), frames);
         }
 
         /// <inheritdoc/>
@@ -75,28 +76,30 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
             if (this.Sampler is NearestNeighborResampler)
             {
-                ParallelFor.WithConfiguration(
-                    0,
-                    height,
+                ParallelHelper.IterateRows(
+                    targetBounds,
                     configuration,
-                    y =>
-                    {
-                        Span<TPixel> destRow = destination.GetPixelRowSpan(y);
-
-                        for (int x = 0; x < width; x++)
+                    rows =>
                         {
-                            var v3 = Vector3.Transform(new Vector3(x, y, 1), matrix);
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                Span<TPixel> destRow = destination.GetPixelRowSpan(y);
 
-                            float z = MathF.Max(v3.Z, Epsilon);
-                            int px = (int)MathF.Round(v3.X / z);
-                            int py = (int)MathF.Round(v3.Y / z);
+                                for (int x = 0; x < width; x++)
+                                {
+                                    var v3 = Vector3.Transform(new Vector3(x, y, 1), matrix);
 
-                            if (sourceBounds.Contains(px, py))
-                            {
-                                destRow[x] = source[px, py];
+                                    float z = MathF.Max(v3.Z, Epsilon);
+                                    int px = (int)MathF.Round(v3.X / z);
+                                    int py = (int)MathF.Round(v3.Y / z);
+
+                                    if (sourceBounds.Contains(px, py))
+                                    {
+                                        destRow[x] = source[px, py];
+                                    }
+                                }
                             }
-                        }
-                    });
+                        });
 
                 return;
             }
@@ -121,92 +124,113 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             using (Buffer2D<float> yBuffer = memoryAllocator.Allocate2D<float>(yLength, height))
             using (Buffer2D<float> xBuffer = memoryAllocator.Allocate2D<float>(xLength, height))
             {
-                ParallelFor.WithConfiguration(
-                    0,
-                    height,
+                ParallelHelper.IterateRows(
+                    targetBounds,
                     configuration,
-                    y =>
-                    {
-                        ref TPixel destRowRef = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
-                        ref float ySpanRef = ref MemoryMarshal.GetReference(yBuffer.GetRowSpan(y));
-                        ref float xSpanRef = ref MemoryMarshal.GetReference(xBuffer.GetRowSpan(y));
-
-                        for (int x = 0; x < width; x++)
+                    rows =>
                         {
-                            // Use the single precision position to calculate correct bounding pixels
-                            // otherwise we get rogue pixels outside of the bounds.
-                            var v3 = Vector3.Transform(new Vector3(x, y, 1), matrix);
-                            float z = MathF.Max(v3.Z, Epsilon);
-
-                            // Using Vector4 with dummy 0-s, because Vector2 SIMD implementation is not reliable:
-                            Vector4 point = new Vector4(v3.X, v3.Y, 0, 0) / z;
-
-                            // Clamp sampling pixel radial extents to the source image edges
-                            Vector4 maxXY = point + radius;
-                            Vector4 minXY = point - radius;
-
-                            // max, maxY, minX, minY
-                            var extents = new Vector4(
-                                MathF.Floor(maxXY.X + .5F),
-                                MathF.Floor(maxXY.Y + .5F),
-                                MathF.Ceiling(minXY.X - .5F),
-                                MathF.Ceiling(minXY.Y - .5F));
-
-                            int right = (int)extents.X;
-                            int bottom = (int)extents.Y;
-                            int left = (int)extents.Z;
-                            int top = (int)extents.W;
-
-                            extents = Vector4.Clamp(extents, Vector4.Zero, maxSource);
-
-                            int maxX = (int)extents.X;
-                            int maxY = (int)extents.Y;
-                            int minX = (int)extents.Z;
-                            int minY = (int)extents.W;
-
-                            if (minX == maxX || minY == maxY)
-                            {
-                                continue;
-                            }
-
-                            // It appears these have to be calculated on-the-fly.
-                            // Precalulating transformed weights would require prior knowledge of every transformed pixel location
-                            // since they can be at sub-pixel positions on both axis.
-                            // I've optimized where I can but am always open to suggestions.
-                            if (yScale > 1 && xScale > 1)
-                            {
-                                CalculateWeightsDown(top, bottom, minY, maxY, point.Y, sampler, yScale, ref ySpanRef, yLength);
-                                CalculateWeightsDown(left, right, minX, maxX, point.X, sampler, xScale, ref xSpanRef, xLength);
-                            }
-                            else
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                CalculateWeightsScaleUp(minY, maxY, point.Y, sampler, ref ySpanRef);
-                                CalculateWeightsScaleUp(minX, maxX, point.X, sampler, ref xSpanRef);
-                            }
+                                ref TPixel destRowRef = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
+                                ref float ySpanRef = ref MemoryMarshal.GetReference(yBuffer.GetRowSpan(y));
+                                ref float xSpanRef = ref MemoryMarshal.GetReference(xBuffer.GetRowSpan(y));
 
-                            // Now multiply the results against the offsets
-                            Vector4 sum = Vector4.Zero;
-                            for (int yy = 0, j = minY; j <= maxY; j++, yy++)
-                            {
-                                float yWeight = Unsafe.Add(ref ySpanRef, yy);
-
-                                for (int xx = 0, i = minX; i <= maxX; i++, xx++)
+                                for (int x = 0; x < width; x++)
                                 {
-                                    float xWeight = Unsafe.Add(ref xSpanRef, xx);
-                                    var vector = source[i, j].ToVector4();
-
-                                    // Values are first premultiplied to prevent darkening of edge pixels
-                                    Vector4 multiplied = vector.Premultiply();
-                                    sum += multiplied * xWeight * yWeight;
+                                    // Use the single precision position to calculate correct bounding pixels
+                                    // otherwise we get rogue pixels outside of the bounds.
+                                    var v3 = Vector3.Transform(new Vector3(x, y, 1), matrix);
+                                    float z = MathF.Max(v3.Z, Epsilon);
+
+                                    // Using Vector4 with dummy 0-s, because Vector2 SIMD implementation is not reliable:
+                                    Vector4 point = new Vector4(v3.X, v3.Y, 0, 0) / z;
+
+                                    // Clamp sampling pixel radial extents to the source image edges
+                                    Vector4 maxXY = point + radius;
+                                    Vector4 minXY = point - radius;
+
+                                    // max, maxY, minX, minY
+                                    var extents = new Vector4(
+                                        MathF.Floor(maxXY.X + .5F),
+                                        MathF.Floor(maxXY.Y + .5F),
+                                        MathF.Ceiling(minXY.X - .5F),
+                                        MathF.Ceiling(minXY.Y - .5F));
+
+                                    int right = (int)extents.X;
+                                    int bottom = (int)extents.Y;
+                                    int left = (int)extents.Z;
+                                    int top = (int)extents.W;
+
+                                    extents = Vector4.Clamp(extents, Vector4.Zero, maxSource);
+
+                                    int maxX = (int)extents.X;
+                                    int maxY = (int)extents.Y;
+                                    int minX = (int)extents.Z;
+                                    int minY = (int)extents.W;
+
+                                    if (minX == maxX || minY == maxY)
+                                    {
+                                        continue;
+                                    }
+
+                                    // It appears these have to be calculated on-the-fly.
+                                    // Precalulating transformed weights would require prior knowledge of every transformed pixel location
+                                    // since they can be at sub-pixel positions on both axis.
+                                    // I've optimized where I can but am always open to suggestions.
+                                    if (yScale > 1 && xScale > 1)
+                                    {
+                                        CalculateWeightsDown(
+                                            top,
+                                            bottom,
+                                            minY,
+                                            maxY,
+                                            point.Y,
+                                            sampler,
+                                            yScale,
+                                            ref ySpanRef,
+                                            yLength);
+
+                                        CalculateWeightsDown(
+                                            left,
+                                            right,
+                                            minX,
+                                            maxX,
+                                            point.X,
+                                            sampler,
+                                            xScale,
+                                            ref xSpanRef,
+                                            xLength);
+                                    }
+                                    else
+                                    {
+                                        CalculateWeightsScaleUp(minY, maxY, point.Y, sampler, ref ySpanRef);
+                                        CalculateWeightsScaleUp(minX, maxX, point.X, sampler, ref xSpanRef);
+                                    }
+
+                                    // Now multiply the results against the offsets
+                                    Vector4 sum = Vector4.Zero;
+                                    for (int yy = 0, j = minY; j <= maxY; j++, yy++)
+                                    {
+                                        float yWeight = Unsafe.Add(ref ySpanRef, yy);
+
+                                        for (int xx = 0, i = minX; i <= maxX; i++, xx++)
+                                        {
+                                            float xWeight = Unsafe.Add(ref xSpanRef, xx);
+                                            var vector = source[i, j].ToVector4();
+
+                                            // Values are first premultiplied to prevent darkening of edge pixels
+                                            Vector4 multiplied = vector.Premultiply();
+                                            sum += multiplied * xWeight * yWeight;
+                                        }
+                                    }
+
+                                    ref TPixel dest = ref Unsafe.Add(ref destRowRef, x);
+
+                                    // Reverse the premultiplication
+                                    dest.PackFromVector4(sum.UnPremultiply());
                                 }
                             }
-
-                            ref TPixel dest = ref Unsafe.Add(ref destRowRef, x);
-
-                            // Reverse the premultiplication
-                            dest.PackFromVector4(sum.UnPremultiply());
-                        }
-                    });
+                        });
             }
         }
 

src/ImageSharp/Processing/Processors/Transforms/ResizeProcessor.cs

@@ -11,6 +11,7 @@ using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
@@ -215,10 +216,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         protected override Image<TPixel> CreateDestination(Image<TPixel> source, Rectangle sourceRectangle)
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
-            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.Width, this.Height, x.MetaData.Clone()));
+            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.Width, this.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
-            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);
+            return new Image<TPixel>(source.GetConfiguration(), source.MetaData.DeepClone(), frames);
         }
 
         /// <inheritdoc/>
@@ -267,26 +268,31 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
             if (this.Sampler is NearestNeighborResampler)
             {
+                var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+
                 // Scaling factors
                 float widthFactor = sourceRectangle.Width / (float)this.ResizeRectangle.Width;
                 float heightFactor = sourceRectangle.Height / (float)this.ResizeRectangle.Height;
 
-                ParallelFor.WithConfiguration(
-                    minY,
-                    maxY,
+                ParallelHelper.IterateRows(
+                    workingRect,
                     configuration,
-                    y =>
-                    {
-                        // Y coordinates of source points
-                        Span<TPixel> sourceRow = source.GetPixelRowSpan((int)(((y - startY) * heightFactor) + sourceY));
-                        Span<TPixel> targetRow = destination.GetPixelRowSpan(y);
-
-                        for (int x = minX; x < maxX; x++)
+                    rows =>
                         {
-                            // X coordinates of source points
-                            targetRow[x] = sourceRow[(int)(((x - startX) * widthFactor) + sourceX)];
-                        }
-                    });
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                // Y coordinates of source points
+                                Span<TPixel> sourceRow =
+                                    source.GetPixelRowSpan((int)(((y - startY) * heightFactor) + sourceY));
+                                Span<TPixel> targetRow = destination.GetPixelRowSpan(y);
+
+                                for (int x = minX; x < maxX; x++)
+                                {
+                                    // X coordinates of source points
+                                    targetRow[x] = sourceRow[(int)(((x - startX) * widthFactor) + sourceX)];
+                                }
+                            }
+                        });
 
                 return;
             }
@@ -300,72 +306,88 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             {
                 firstPassPixels.MemorySource.Clear();
 
-                ParallelFor.WithTemporaryBuffer(
-                    0,
-                    sourceRectangle.Bottom,
+                var processColsRect = new Rectangle(0, 0, source.Width, sourceRectangle.Bottom);
+
+                ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
+                    processColsRect,
                     configuration,
-                    source.Width,
-                    (int y, IMemoryOwner<Vector4> tempRowBuffer) =>
+                    (rows, tempRowBuffer) =>
                         {
-                            ref Vector4 firstPassRow = ref MemoryMarshal.GetReference(firstPassPixels.GetRowSpan(y));
-                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                            Span<Vector4> tempRowSpan = tempRowBuffer.GetSpan();
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                ref Vector4 firstPassRow =
+                                    ref MemoryMarshal.GetReference(firstPassPixels.GetRowSpan(y));
+                                Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                                Span<Vector4> tempRowSpan = tempRowBuffer.Span;
 
-                            PixelOperations<TPixel>.Instance.ToVector4(sourceRow, tempRowSpan, sourceRow.Length);
+                                PixelOperations<TPixel>.Instance.ToVector4(sourceRow, tempRowSpan, sourceRow.Length);
 
-                            if (this.Compand)
-                            {
-                                for (int x = minX; x < maxX; x++)
+                                if (this.Compand)
                                 {
-                                    WeightsWindow window = this.horizontalWeights.Weights[x - startX];
-                                    Unsafe.Add(ref firstPassRow, x) = window.ComputeExpandedWeightedRowSum(tempRowSpan, sourceX);
+                                    for (int x = minX; x < maxX; x++)
+                                    {
+                                        WeightsWindow window = this.horizontalWeights.Weights[x - startX];
+                                        Unsafe.Add(ref firstPassRow, x) =
+                                            window.ComputeExpandedWeightedRowSum(tempRowSpan, sourceX);
+                                    }
                                 }
-                            }
-                            else
-                            {
-                                for (int x = minX; x < maxX; x++)
+                                else
                                 {
-                                    WeightsWindow window = this.horizontalWeights.Weights[x - startX];
-                                    Unsafe.Add(ref firstPassRow, x) = window.ComputeWeightedRowSum(tempRowSpan, sourceX);
+                                    for (int x = minX; x < maxX; x++)
+                                    {
+                                        WeightsWindow window = this.horizontalWeights.Weights[x - startX];
+                                        Unsafe.Add(ref firstPassRow, x) =
+                                            window.ComputeWeightedRowSum(tempRowSpan, sourceX);
+                                    }
                                 }
                             }
                         });
 
+                var processRowsRect = Rectangle.FromLTRB(0, minY, width, maxY);
+
                 // Now process the rows.
-                ParallelFor.WithConfiguration(
-                    minY,
-                    maxY,
+                ParallelHelper.IterateRows(
+                    processRowsRect,
                     configuration,
-                    y =>
-                    {
-                        // Ensure offsets are normalized for cropping and padding.
-                        WeightsWindow window = this.verticalWeights.Weights[y - startY];
-                        ref TPixel targetRow = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
-
-                        if (this.Compand)
-                        {
-                            for (int x = 0; x < width; x++)
-                            {
-                                // Destination color components
-                                Vector4 destinationVector = window.ComputeWeightedColumnSum(firstPassPixels, x, sourceY);
-                                destinationVector = destinationVector.Compress();
-
-                                ref TPixel pixel = ref Unsafe.Add(ref targetRow, x);
-                                pixel.PackFromVector4(destinationVector);
-                            }
-                        }
-                        else
+                    rows =>
                         {
-                            for (int x = 0; x < width; x++)
+                            for (int y = rows.Min; y < rows.Max; y++)
                             {
-                                // Destination color components
-                                Vector4 destinationVector = window.ComputeWeightedColumnSum(firstPassPixels, x, sourceY);
+                                // Ensure offsets are normalized for cropping and padding.
+                                WeightsWindow window = this.verticalWeights.Weights[y - startY];
+                                ref TPixel targetRow = ref MemoryMarshal.GetReference(destination.GetPixelRowSpan(y));
 
-                                ref TPixel pixel = ref Unsafe.Add(ref targetRow, x);
-                                pixel.PackFromVector4(destinationVector);
+                                if (this.Compand)
+                                {
+                                    for (int x = 0; x < width; x++)
+                                    {
+                                        // Destination color components
+                                        Vector4 destinationVector = window.ComputeWeightedColumnSum(
+                                            firstPassPixels,
+                                            x,
+                                            sourceY);
+                                        destinationVector = destinationVector.Compress();
+
+                                        ref TPixel pixel = ref Unsafe.Add(ref targetRow, x);
+                                        pixel.PackFromVector4(destinationVector);
+                                    }
+                                }
+                                else
+                                {
+                                    for (int x = 0; x < width; x++)
+                                    {
+                                        // Destination color components
+                                        Vector4 destinationVector = window.ComputeWeightedColumnSum(
+                                            firstPassPixels,
+                                            x,
+                                            sourceY);
+
+                                        ref TPixel pixel = ref Unsafe.Add(ref targetRow, x);
+                                        pixel.PackFromVector4(destinationVector);
+                                    }
+                                }
                             }
-                        }
-                    });
+                        });
             }
         }
 

src/ImageSharp/Processing/Processors/Transforms/RotateProcessor.cs

@@ -5,6 +5,7 @@ using System;
 using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Processors.Transforms;
 using SixLabors.Primitives;
@@ -147,25 +148,27 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             int height = source.Height;
             Rectangle destinationBounds = destination.Bounds();
 
-            ParallelFor.WithConfiguration(
-                0,
-                height,
+            ParallelHelper.IterateRows(
+                source.Bounds(),
                 configuration,
-                y =>
-                {
-                    Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                    for (int x = 0; x < width; x++)
+                rows =>
                     {
-                        int newX = height - y - 1;
-                        newX = height - newX - 1;
-                        int newY = width - x - 1;
-
-                        if (destinationBounds.Contains(newX, newY))
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            destination[newX, newY] = sourceRow[x];
+                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                            for (int x = 0; x < width; x++)
+                            {
+                                int newX = height - y - 1;
+                                newX = height - newX - 1;
+                                int newY = width - x - 1;
+
+                                if (destinationBounds.Contains(newX, newY))
+                                {
+                                    destination[newX, newY] = sourceRow[x];
+                                }
+                            }
                         }
-                    }
-                });
+                    });
         }
 
         /// <summary>
@@ -179,20 +182,22 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             int width = source.Width;
             int height = source.Height;
 
-            ParallelFor.WithConfiguration(
-                0,
-                height,
+            ParallelHelper.IterateRows(
+                source.Bounds(),
                 configuration,
-                y =>
-                {
-                    Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                    Span<TPixel> targetRow = destination.GetPixelRowSpan(height - y - 1);
-
-                    for (int x = 0; x < width; x++)
+                rows =>
                     {
-                        targetRow[width - x - 1] = sourceRow[x];
-                    }
-                });
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                            Span<TPixel> targetRow = destination.GetPixelRowSpan(height - y - 1);
+
+                            for (int x = 0; x < width; x++)
+                            {
+                                targetRow[width - x - 1] = sourceRow[x];
+                            }
+                        }
+                    });
         }
 
         /// <summary>
@@ -207,22 +212,25 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             int height = source.Height;
             Rectangle destinationBounds = destination.Bounds();
 
-            ParallelFor.WithConfiguration(
-                0,
-                height,
+            ParallelHelper.IterateRows(
+                source.Bounds(),
                 configuration,
-                y =>
-                {
-                    Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
-                    int newX = height - y - 1;
-                    for (int x = 0; x < width; x++)
+                rows =>
                     {
-                        if (destinationBounds.Contains(newX, x))
+                        for (int y = rows.Min; y < rows.Max; y++)
                         {
-                            destination[newX, x] = sourceRow[x];
+                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y);
+                            int newX = height - y - 1;
+                            for (int x = 0; x < width; x++)
+                            {
+                                // TODO: Optimize this:
+                                if (destinationBounds.Contains(newX, x))
+                                {
+                                    destination[newX, x] = sourceRow[x];
+                                }
+                            }
                         }
-                    }
-                });
+                    });
         }
     }
 }

tests/ImageSharp.Benchmarks/Codecs/CopyPixels.cs

@@ -1,115 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Threading.Tasks;
-
-using BenchmarkDotNet.Attributes;
-
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.PixelFormats;
-
-namespace SixLabors.ImageSharp.Benchmarks.Codecs
-{
-    public class CopyPixels : BenchmarkBase
-    {
-        [Benchmark(Baseline = true, Description = "PixelAccessor Copy by indexer")]
-        public Rgba32 CopyByPixelAccesor()
-        {
-            using (var source = new Image<Rgba32>(1024, 768))
-            using (var target = new Image<Rgba32>(1024, 768))
-            {
-                Buffer2D<Rgba32> sourcePixels = source.GetRootFramePixelBuffer();
-                Buffer2D<Rgba32> targetPixels = target.GetRootFramePixelBuffer();
-                ParallelFor.WithConfiguration(
-                    0,
-                    source.Height,
-                    Configuration.Default,
-                    y =>
-                        {
-                            for (int x = 0; x < source.Width; x++)
-                            {
-                                targetPixels[x, y] = sourcePixels[x, y];
-                            }
-                        });
-
-                return targetPixels[0, 0];
-            }
-        }
-
-        [Benchmark(Description = "PixelAccessor Copy by Span")]
-        public Rgba32 CopyByPixelAccesorSpan()
-        {
-            using (var source = new Image<Rgba32>(1024, 768))
-            using (var target = new Image<Rgba32>(1024, 768))
-            {
-                Buffer2D<Rgba32> sourcePixels = source.GetRootFramePixelBuffer();
-                Buffer2D<Rgba32> targetPixels = target.GetRootFramePixelBuffer();
-                ParallelFor.WithConfiguration(
-                    0,
-                    source.Height,
-                    Configuration.Default,
-                    y =>
-                        {
-                            Span<Rgba32> sourceRow = sourcePixels.GetRowSpan(y);
-                            Span<Rgba32> targetRow = targetPixels.GetRowSpan(y);
-
-                            for (int x = 0; x < source.Width; x++)
-                            {
-                                targetRow[x] = sourceRow[x];
-                            }
-                        });
-
-                return targetPixels[0, 0];
-            }
-        }
-
-        [Benchmark(Description = "Copy by indexer")]
-        public Rgba32 Copy()
-        {
-            using (var source = new Image<Rgba32>(1024, 768))
-            using (var target = new Image<Rgba32>(1024, 768))
-            {
-                ParallelFor.WithConfiguration(
-                    0,
-                    source.Height,
-                    Configuration.Default,
-                    y =>
-                        {
-                            for (int x = 0; x < source.Width; x++)
-                            {
-                                target[x, y] = source[x, y];
-                            }
-                        });
-
-                return target[0, 0];
-            }
-        }
-
-        [Benchmark(Description = "Copy by Span")]
-        public Rgba32 CopySpan()
-        {
-            using (var source = new Image<Rgba32>(1024, 768))
-            using (var target = new Image<Rgba32>(1024, 768))
-            {
-                ParallelFor.WithConfiguration(
-                    0,
-                    source.Height,
-                    Configuration.Default,
-                    y =>
-                        {
-                            Span<Rgba32> sourceRow = source.Frames.RootFrame.GetPixelRowSpan(y);
-                            Span<Rgba32> targetRow = target.Frames.RootFrame.GetPixelRowSpan(y);
-
-                            for (int x = 0; x < source.Width; x++)
-                            {
-                                targetRow[x] = sourceRow[x];
-                            }
-                        });
-
-                return target[0, 0];
-            }
-        }
-    }
-}

tests/ImageSharp.Benchmarks/Samplers/Glow.cs

@@ -9,6 +9,7 @@ using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;
 
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Processors;
 using SixLabors.ImageSharp.Processing.Processors.Overlays;
@@ -112,26 +113,29 @@ namespace SixLabors.ImageSharp.Benchmarks
                     Buffer2D<TPixel> sourcePixels = source.PixelBuffer;
                     rowColors.GetSpan().Fill(glowColor);
 
-                    ParallelFor.WithConfiguration(
-                        minY,
-                        maxY,
+                    var workingRect = Rectangle.FromLTRB(minX, minY, maxX, maxY);
+                    ParallelHelper.IterateRows(
+                        workingRect,
                         configuration,
-                        y =>
+                        rows =>
                             {
-                                int offsetY = y - startY;
-
-                                for (int x = minX; x < maxX; x++)
+                                for (int y = rows.Min; y < rows.Max; y++)
                                 {
-                                    int offsetX = x - startX;
-                                    float distance = Vector2.Distance(centre, new Vector2(offsetX, offsetY));
-                                    Vector4 sourceColor = sourcePixels[offsetX, offsetY].ToVector4();
-                                    TPixel packed = default(TPixel);
-                                    packed.PackFromVector4(
-                                        PremultipliedLerp(
-                                            sourceColor,
-                                            glowColor.ToVector4(),
-                                            1 - (.95F * (distance / maxDistance))));
-                                    sourcePixels[offsetX, offsetY] = packed;
+                                    int offsetY = y - startY;
+
+                                    for (int x = minX; x < maxX; x++)
+                                    {
+                                        int offsetX = x - startX;
+                                        float distance = Vector2.Distance(centre, new Vector2(offsetX, offsetY));
+                                        Vector4 sourceColor = sourcePixels[offsetX, offsetY].ToVector4();
+                                        TPixel packed = default(TPixel);
+                                        packed.PackFromVector4(
+                                            PremultipliedLerp(
+                                                sourceColor,
+                                                glowColor.ToVector4(),
+                                                1 - (.95F * (distance / maxDistance))));
+                                        sourcePixels[offsetX, offsetY] = packed;
+                                    }
                                 }
                             });
                 }

tests/ImageSharp.Tests/ConfigurationTests.cs

@@ -23,7 +23,7 @@ namespace SixLabors.ImageSharp.Tests
         {
             // the shallow copy of configuration should behave exactly like the default configuration,
             // so by using the copy, we test both the default and the copy.
-            this.DefaultConfiguration = Configuration.CreateDefaultInstance().ShallowCopy();
+            this.DefaultConfiguration = Configuration.CreateDefaultInstance().Clone();
             this.ConfigurationEmpty = new Configuration();
         }
 

tests/ImageSharp.Tests/Drawing/FillPatternTests.cs

@@ -54,172 +54,225 @@ namespace SixLabors.ImageSharp.Tests.Drawing
         [Fact]
         public void ImageShouldBeFloodFilledWithPercent10()
         {
-            this.Test("Percent10", Rgba32.Blue, Brushes.Percent10(Rgba32.HotPink, Rgba32.LimeGreen),
+            this.Test(
+                "Percent10",
+                Rgba32.Blue,
+                Brushes.Percent10(Rgba32.HotPink, Rgba32.LimeGreen),
                 new[,]
-                {
-                { Rgba32.HotPink , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink , Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen}
-            });
+                    {
+                        { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithPercent10Transparent()
         {
-            Test("Percent10_Transparent", Rgba32.Blue, Brushes.Percent10(Rgba32.HotPink),
-            new Rgba32[,] {
-                { Rgba32.HotPink , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink , Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue}
-            });
+            this.Test(
+                "Percent10_Transparent",
+                Rgba32.Blue,
+                Brushes.Percent10(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithPercent20()
         {
-            Test("Percent20", Rgba32.Blue, Brushes.Percent20(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.HotPink , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink , Rgba32.LimeGreen},
-                { Rgba32.HotPink , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink , Rgba32.LimeGreen}
-           });
+            this.Test(
+                "Percent20",
+                Rgba32.Blue,
+                Brushes.Percent20(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen },
+                        { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithPercent20_transparent()
         {
-            Test("Percent20_Transparent", Rgba32.Blue, Brushes.Percent20(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.HotPink , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink , Rgba32.Blue},
-                { Rgba32.HotPink , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink , Rgba32.Blue}
-           });
+            this.Test(
+                "Percent20_Transparent",
+                Rgba32.Blue,
+                Brushes.Percent20(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue },
+                        { Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithHorizontal()
         {
-            Test("Horizontal", Rgba32.Blue, Brushes.Horizontal(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.LimeGreen , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink , Rgba32.HotPink},
-                { Rgba32.LimeGreen , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen , Rgba32.LimeGreen}
-           });
+            this.Test(
+                "Horizontal",
+                Rgba32.Blue,
+                Brushes.Horizontal(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithHorizontal_transparent()
         {
-            Test("Horizontal_Transparent", Rgba32.Blue, Brushes.Horizontal(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.Blue , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink , Rgba32.HotPink},
-                { Rgba32.Blue , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue , Rgba32.Blue}
-           });
+            this.Test(
+                "Horizontal_Transparent",
+                Rgba32.Blue,
+                Brushes.Horizontal(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue }
+                    });
         }
 
-
-
         [Fact]
         public void ImageShouldBeFloodFilledWithMin()
         {
-            Test("Min", Rgba32.Blue, Brushes.Min(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.LimeGreen , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen , Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen , Rgba32.LimeGreen},
-                { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink , Rgba32.HotPink}
-           });
+            this.Test(
+                "Min",
+                Rgba32.Blue,
+                Brushes.Min(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithMin_transparent()
         {
-            Test("Min_Transparent", Rgba32.Blue, Brushes.Min(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.Blue , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue , Rgba32.Blue, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue , Rgba32.Blue},
-                { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink , Rgba32.HotPink},
-           });
+            this.Test(
+                "Min_Transparent",
+                Rgba32.Blue,
+                Brushes.Min(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink, Rgba32.HotPink },
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithVertical()
         {
-            Test("Vertical", Rgba32.Blue, Brushes.Vertical(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen}
-           });
+            this.Test(
+                "Vertical",
+                Rgba32.Blue,
+                Brushes.Vertical(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithVertical_transparent()
         {
-            Test("Vertical_Transparent", Rgba32.Blue, Brushes.Vertical(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue},
-                { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue}
-           });
+            this.Test(
+                "Vertical_Transparent",
+                Rgba32.Blue,
+                Brushes.Vertical(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithForwardDiagonal()
         {
-            Test("ForwardDiagonal", Rgba32.Blue, Brushes.ForwardDiagonal(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen}
-           });
+            this.Test(
+                "ForwardDiagonal",
+                Rgba32.Blue,
+                Brushes.ForwardDiagonal(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithForwardDiagonal_transparent()
         {
-            Test("ForwardDiagonal_Transparent", Rgba32.Blue, Brushes.ForwardDiagonal(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.Blue,    Rgba32.Blue,    Rgba32.Blue,    Rgba32.HotPink},
-                { Rgba32.Blue,    Rgba32.Blue,    Rgba32.HotPink, Rgba32.Blue},
-                { Rgba32.Blue,    Rgba32.HotPink, Rgba32.Blue,    Rgba32.Blue},
-                { Rgba32.HotPink, Rgba32.Blue,    Rgba32.Blue,    Rgba32.Blue}
-           });
+            this.Test(
+                "ForwardDiagonal_Transparent",
+                Rgba32.Blue,
+                Brushes.ForwardDiagonal(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithBackwardDiagonal()
         {
-            Test("BackwardDiagonal", Rgba32.Blue, Brushes.BackwardDiagonal(Rgba32.HotPink, Rgba32.LimeGreen),
-           new Rgba32[,] {
-                { Rgba32.HotPink,   Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.HotPink,   Rgba32.LimeGreen, Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink,   Rgba32.LimeGreen},
-                { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink}
-           });
+            this.Test(
+                "BackwardDiagonal",
+                Rgba32.Blue,
+                Brushes.BackwardDiagonal(Rgba32.HotPink, Rgba32.LimeGreen),
+                new Rgba32[,]
+                    {
+                        { Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink, Rgba32.LimeGreen },
+                        { Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.LimeGreen, Rgba32.HotPink }
+                    });
         }
 
         [Fact]
         public void ImageShouldBeFloodFilledWithBackwardDiagonal_transparent()
         {
-            Test("BackwardDiagonal_Transparent", Rgba32.Blue, Brushes.BackwardDiagonal(Rgba32.HotPink),
-           new Rgba32[,] {
-                { Rgba32.HotPink, Rgba32.Blue,    Rgba32.Blue,    Rgba32.Blue},
-                { Rgba32.Blue,    Rgba32.HotPink, Rgba32.Blue,    Rgba32.Blue},
-                { Rgba32.Blue,    Rgba32.Blue,    Rgba32.HotPink, Rgba32.Blue},
-                { Rgba32.Blue,    Rgba32.Blue,    Rgba32.Blue,    Rgba32.HotPink}
-           });
+            this.Test(
+                "BackwardDiagonal_Transparent",
+                Rgba32.Blue,
+                Brushes.BackwardDiagonal(Rgba32.HotPink),
+                new Rgba32[,]
+                    {
+                        { Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink, Rgba32.Blue },
+                        { Rgba32.Blue, Rgba32.Blue, Rgba32.Blue, Rgba32.HotPink }
+                    });
         }
     }
-}
+}

tests/ImageSharp.Tests/Drawing/FillSolidBrushTests.cs

@@ -1,20 +1,21 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
+
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Primitives;
+using SixLabors.ImageSharp.Processing;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
+using SixLabors.Primitives;
 using SixLabors.Shapes;
+
 using Xunit;
+
 // ReSharper disable InconsistentNaming
 
 namespace SixLabors.ImageSharp.Tests.Drawing
 {
-    using System;
-
-    using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
-    using SixLabors.Primitives;
-
     [GroupOutput("Drawing")]
     public class FillSolidBrushTests
     {
@@ -55,7 +56,9 @@ namespace SixLabors.ImageSharp.Tests.Drawing
         [Theory]
         [WithSolidFilledImages(16, 16, "Red", PixelTypes.Rgba32, "Blue")]
         [WithSolidFilledImages(16, 16, "Yellow", PixelTypes.Rgba32, "Khaki")]
-        public void WhenColorIsOpaque_OverridePreviousColor<TPixel>(TestImageProvider<TPixel> provider, string newColorName)
+        public void WhenColorIsOpaque_OverridePreviousColor<TPixel>(
+            TestImageProvider<TPixel> provider,
+            string newColorName)
             where TPixel : struct, IPixel<TPixel>
         {
             using (Image<TPixel> image = provider.GetImage())
@@ -63,7 +66,11 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                 TPixel color = TestUtils.GetPixelOfNamedColor<TPixel>(newColorName);
                 image.Mutate(c => c.Fill(color));
 
-                image.DebugSave(provider, newColorName, appendPixelTypeToFileName: false, appendSourceFileOrDescription: false);
+                image.DebugSave(
+                    provider,
+                    newColorName,
+                    appendPixelTypeToFileName: false,
+                    appendSourceFileOrDescription: false);
                 image.ComparePixelBufferTo(color);
             }
         }
@@ -84,7 +91,12 @@ namespace SixLabors.ImageSharp.Tests.Drawing
         [Theory]
         [WithSolidFilledImages(16, 16, "Red", PixelTypes.Rgba32, 5, 7, 3, 8)]
         [WithSolidFilledImages(16, 16, "Red", PixelTypes.Rgba32, 8, 5, 6, 4)]
-        public void FillRegion_WorksOnWrappedMemoryImage<TPixel>(TestImageProvider<TPixel> provider, int x0, int y0, int w, int h)
+        public void FillRegion_WorksOnWrappedMemoryImage<TPixel>(
+            TestImageProvider<TPixel> provider,
+            int x0,
+            int y0,
+            int w,
+            int h)
             where TPixel : struct, IPixel<TPixel>
         {
             FormattableString testDetails = $"(x{x0},y{y0},w{w},h{h})";
@@ -105,27 +117,22 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                     { false, "Blue", 1.0f, PixelColorBlendingMode.Normal, 0.5f },
                     { false, "Green", 0.5f, PixelColorBlendingMode.Normal, 0.3f },
                     { false, "HotPink", 0.8f, PixelColorBlendingMode.Normal, 0.8f },
-
                     { false, "Blue", 0.5f, PixelColorBlendingMode.Multiply, 1.0f },
                     { false, "Blue", 1.0f, PixelColorBlendingMode.Multiply, 0.5f },
                     { false, "Green", 0.5f, PixelColorBlendingMode.Multiply, 0.3f },
                     { false, "HotPink", 0.8f, PixelColorBlendingMode.Multiply, 0.8f },
-
                     { false, "Blue", 0.5f, PixelColorBlendingMode.Add, 1.0f },
                     { false, "Blue", 1.0f, PixelColorBlendingMode.Add, 0.5f },
                     { false, "Green", 0.5f, PixelColorBlendingMode.Add, 0.3f },
                     { false, "HotPink", 0.8f, PixelColorBlendingMode.Add, 0.8f },
-
                     { true, "Blue", 0.5f, PixelColorBlendingMode.Normal, 1.0f },
                     { true, "Blue", 1.0f, PixelColorBlendingMode.Normal, 0.5f },
                     { true, "Green", 0.5f, PixelColorBlendingMode.Normal, 0.3f },
                     { true, "HotPink", 0.8f, PixelColorBlendingMode.Normal, 0.8f },
-
                     { true, "Blue", 0.5f, PixelColorBlendingMode.Multiply, 1.0f },
                     { true, "Blue", 1.0f, PixelColorBlendingMode.Multiply, 0.5f },
                     { true, "Green", 0.5f, PixelColorBlendingMode.Multiply, 0.3f },
                     { true, "HotPink", 0.8f, PixelColorBlendingMode.Multiply, 0.8f },
-
                     { true, "Blue", 0.5f, PixelColorBlendingMode.Add, 1.0f },
                     { true, "Blue", 1.0f, PixelColorBlendingMode.Add, 0.5f },
                     { true, "Green", 0.5f, PixelColorBlendingMode.Add, 0.3f },
@@ -155,8 +162,7 @@ namespace SixLabors.ImageSharp.Tests.Drawing
 
                 var options = new GraphicsOptions(false)
                                   {
-                                      ColorBlendingMode = blenderMode,
-                                      BlendPercentage = blendPercentage
+                                      ColorBlendingMode = blenderMode, BlendPercentage = blendPercentage
                                   };
 
                 if (triggerFillRegion)
@@ -185,11 +191,13 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                     appendPixelTypeToFileName: false,
                     appendSourceFileOrDescription: false);
 
-                PixelBlender<TPixel> blender = PixelOperations<TPixel>.Instance.GetPixelBlender(blenderMode, PixelAlphaCompositionMode.SrcOver);
+                PixelBlender<TPixel> blender = PixelOperations<TPixel>.Instance.GetPixelBlender(
+                    blenderMode,
+                    PixelAlphaCompositionMode.SrcOver);
                 TPixel expectedPixel = blender.Blend(bgColor, fillColor, blendPercentage);
 
                 image.ComparePixelBufferTo(expectedPixel);
             }
         }
     }
-}
+}

tests/ImageSharp.Tests/Formats/Bmp/BmpMetaDataTests.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Bmp;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Bmp
+{
+    public class BmpMetaDataTests
+    {
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var meta = new BmpMetaData() { BitsPerPixel = BmpBitsPerPixel.Pixel24 };
+            var clone = (BmpMetaData)meta.DeepClone();
+
+            clone.BitsPerPixel = BmpBitsPerPixel.Pixel32;
+
+            Assert.False(meta.BitsPerPixel.Equals(clone.BitsPerPixel));
+        }
+    }
+}

tests/ImageSharp.Tests/Formats/Gif/GifFrameMetaDataTests.cs

@@ -0,0 +1,32 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Gif;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Gif
+{
+    public class GifFrameMetaDataTests
+    {
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var meta = new GifFrameMetaData()
+            {
+                FrameDelay = 1,
+                DisposalMethod = GifDisposalMethod.RestoreToBackground,
+                ColorTableLength = 2
+            };
+
+            var clone = (GifFrameMetaData)meta.DeepClone();
+
+            clone.FrameDelay = 2;
+            clone.DisposalMethod = GifDisposalMethod.RestoreToPrevious;
+            clone.ColorTableLength = 1;
+
+            Assert.False(meta.FrameDelay.Equals(clone.FrameDelay));
+            Assert.False(meta.DisposalMethod.Equals(clone.DisposalMethod));
+            Assert.False(meta.ColorTableLength.Equals(clone.ColorTableLength));
+        }
+    }
+}

tests/ImageSharp.Tests/Formats/Gif/GifMetaDataTests.cs

@@ -0,0 +1,32 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Gif;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Gif
+{
+    public class GifMetaDataTests
+    {
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var meta = new GifMetaData()
+            {
+                RepeatCount = 1,
+                ColorTableMode = GifColorTableMode.Global,
+                GlobalColorTableLength = 2
+            };
+
+            var clone = (GifMetaData)meta.DeepClone();
+
+            clone.RepeatCount = 2;
+            clone.ColorTableMode = GifColorTableMode.Local;
+            clone.GlobalColorTableLength = 1;
+
+            Assert.False(meta.RepeatCount.Equals(clone.RepeatCount));
+            Assert.False(meta.ColorTableMode.Equals(clone.ColorTableMode));
+            Assert.False(meta.GlobalColorTableLength.Equals(clone.GlobalColorTableLength));
+        }
+    }
+}

tests/ImageSharp.Tests/Formats/ImageFormatManagerTests.cs

@@ -2,17 +2,15 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using Moq;
 using SixLabors.ImageSharp.Formats;
-using SixLabors.ImageSharp.IO;
-using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.Formats.Bmp;
-using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Gif;
-using Moq;
+using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.PixelFormats;
 using Xunit;
 
 
@@ -27,7 +25,7 @@ namespace SixLabors.ImageSharp.Tests
         {
             this.DefaultFormatsManager = Configuration.CreateDefaultInstance().ImageFormatsManager;
             this.FormatsManagerEmpty = new ImageFormatManager();
-        }        
+        }
 
         [Fact]
         public void IfAutoloadWellKnownFormatsIsTrueAllFormatsAreLoaded()
@@ -114,7 +112,7 @@ namespace SixLabors.ImageSharp.Tests
             IImageDecoder found2 = this.FormatsManagerEmpty.FindDecoder(TestFormat.GlobalTestFormat);
             Assert.Equal(decoder2, found2);
             Assert.NotEqual(found, found2);
-        }        
+        }
 
         [Fact]
         public void AddFormatCallsConfig()
@@ -125,5 +123,24 @@ namespace SixLabors.ImageSharp.Tests
 
             provider.Verify(x => x.Configure(config));
         }
+
+        [Fact]
+        public void DetectFormatAllocatesCleanBuffer()
+        {
+            byte[] jpegImage;
+            using (var buffer = new MemoryStream())
+            {
+                using (var image = new Image<Rgba32>(100, 100))
+                {
+                    image.SaveAsJpeg(buffer);
+                    jpegImage = buffer.ToArray();
+                }
+            }
+
+            byte[] invalidImage = { 1, 2, 3 };
+
+            Assert.Equal(Image.DetectFormat(jpegImage), JpegFormat.Instance);
+            Assert.True(Image.DetectFormat(invalidImage) is null);
+        }
     }
 }

tests/ImageSharp.Tests/Formats/Jpg/JpegMetaDataTests.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Jpeg;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Jpg
+{
+    public class JpegMetaDataTests
+    {
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var meta = new JpegMetaData() { Quality = 50 };
+            var clone = (JpegMetaData)meta.DeepClone();
+
+            clone.Quality = 99;
+
+            Assert.False(meta.Quality.Equals(clone.Quality));
+        }
+    }
+}

tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs

@@ -9,7 +9,6 @@ using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Quantization;
 using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 
@@ -19,10 +18,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
 {
     public class PngEncoderTests
     {
-        // This is bull. Failing online for no good reason. 
-        // The images are an exact match. Maybe the submodule isn't updating?
-        private const float ToleranceThresholdForPaletteEncoder = 1.3F / 100;
-
         public static readonly TheoryData<string, PngBitDepth> PngBitDepthFiles =
         new TheoryData<string, PngBitDepth>
         {
@@ -137,19 +132,32 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
         }
 
         [Theory]
-        [WithTestPatternImages(24, 24, PixelTypes.Rgba64, PngColorType.Rgb)]
-        [WithTestPatternImages(24, 24, PixelTypes.Rgba64, PngColorType.RgbWithAlpha)]
-        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.RgbWithAlpha)]
-        public void WorksWithBitDepth16<TPixel>(TestImageProvider<TPixel> provider, PngColorType pngColorType)
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.Rgb, PngBitDepth.Bit8)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba64, PngColorType.Rgb, PngBitDepth.Bit16)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.RgbWithAlpha, PngBitDepth.Bit8)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba64, PngColorType.RgbWithAlpha, PngBitDepth.Bit16)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.Palette, PngBitDepth.Bit1)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.Palette, PngBitDepth.Bit2)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.Palette, PngBitDepth.Bit4)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.Palette, PngBitDepth.Bit8)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgb24, PngColorType.Grayscale, PngBitDepth.Bit1)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgb24, PngColorType.Grayscale, PngBitDepth.Bit2)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgb24, PngColorType.Grayscale, PngBitDepth.Bit4)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgb24, PngColorType.Grayscale, PngBitDepth.Bit8)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgb48, PngColorType.Grayscale, PngBitDepth.Bit16)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba32, PngColorType.GrayscaleWithAlpha, PngBitDepth.Bit8)]
+        [WithTestPatternImages(24, 24, PixelTypes.Rgba64, PngColorType.GrayscaleWithAlpha, PngBitDepth.Bit16)]
+        public void WorksWithAllBitDepths<TPixel>(TestImageProvider<TPixel> provider, PngColorType pngColorType, PngBitDepth pngBitDepth)
             where TPixel : struct, IPixel<TPixel>
         {
             TestPngEncoderCore(
                 provider,
                 pngColorType,
                 PngFilterMethod.Adaptive,
-                PngBitDepth.Bit16,
+                pngBitDepth,
                 appendPngColorType: true,
-                appendPixelType: true);
+                appendPixelType: true,
+                appendPngBitDepth: true);
         }
 
         [Theory]
@@ -166,87 +174,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
                 appendPaletteSize: true);
         }
 
-        private static bool HasAlpha(PngColorType pngColorType) =>
-            pngColorType == PngColorType.GrayscaleWithAlpha || pngColorType == PngColorType.RgbWithAlpha;
-
-        private static void TestPngEncoderCore<TPixel>(
-            TestImageProvider<TPixel> provider,
-            PngColorType pngColorType,
-            PngFilterMethod pngFilterMethod,
-            PngBitDepth bitDepth,
-            int compressionLevel = 6,
-            int paletteSize = 255,
-            bool appendPngColorType = false,
-            bool appendPngFilterMethod = false,
-            bool appendPixelType = false,
-            bool appendCompressionLevel = false,
-            bool appendPaletteSize = false)
-            where TPixel : struct, IPixel<TPixel>
-        {
-            using (Image<TPixel> image = provider.GetImage())
-            {
-                if (!HasAlpha(pngColorType))
-                {
-                    image.Mutate(c => c.MakeOpaque());
-                }
-
-                var encoder = new PngEncoder
-                {
-                    ColorType = pngColorType,
-                    FilterMethod = pngFilterMethod,
-                    CompressionLevel = compressionLevel,
-                    BitDepth = bitDepth,
-                    Quantizer = new WuQuantizer(paletteSize)
-                };
-
-                string pngColorTypeInfo = appendPngColorType ? pngColorType.ToString() : string.Empty;
-                string pngFilterMethodInfo = appendPngFilterMethod ? pngFilterMethod.ToString() : string.Empty;
-                string compressionLevelInfo = appendCompressionLevel ? $"_C{compressionLevel}" : string.Empty;
-                string paletteSizeInfo = appendPaletteSize ? $"_PaletteSize-{paletteSize}" : string.Empty;
-                string debugInfo = $"{pngColorTypeInfo}{pngFilterMethodInfo}{compressionLevelInfo}{paletteSizeInfo}";
-                //string referenceInfo = $"{pngColorTypeInfo}";
-
-                // Does DebugSave & load reference CompareToReferenceInput():
-                string actualOutputFile = ((ITestImageProvider)provider).Utility.SaveTestOutputFile(image, "png", encoder, debugInfo, appendPixelType);
-
-                if (TestEnvironment.IsMono)
-                {
-                    // There are bugs in mono's System.Drawing implementation, reference decoders are not always reliable!
-                    return;
-                }
-
-                IImageDecoder referenceDecoder = TestEnvironment.GetReferenceDecoder(actualOutputFile);
-                string referenceOutputFile = ((ITestImageProvider)provider).Utility.GetReferenceOutputFileName("png", debugInfo, appendPixelType, true);
-
-                bool referenceOutputFileExists = File.Exists(referenceOutputFile);
-
-                using (var actualImage = Image.Load<TPixel>(actualOutputFile, referenceDecoder))
-                {
-                    // TODO: Do we still need the reference output files?
-                    Image<TPixel> referenceImage = referenceOutputFileExists
-                                               ? Image.Load<TPixel>(referenceOutputFile, referenceDecoder)
-                                               : image;
-
-                    float paletteToleranceHack = 80f / paletteSize;
-                    paletteToleranceHack *= paletteToleranceHack;
-                    ImageComparer comparer = pngColorType == PngColorType.Palette
-                                                 ? ImageComparer.Tolerant(ToleranceThresholdForPaletteEncoder * paletteToleranceHack)
-                                                 : ImageComparer.Exact;
-                    try
-                    {
-                        comparer.VerifySimilarity(referenceImage, actualImage);
-                    }
-                    finally
-                    {
-                        if (referenceOutputFileExists)
-                        {
-                            referenceImage.Dispose();
-                        }
-                    }
-                }
-            }
-        }
-
         [Theory]
         [WithBlankImages(1, 1, PixelTypes.Rgba32)]
         public void WritesFileMarker<TPixel>(TestImageProvider<TPixel> provider)
@@ -321,5 +248,54 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
                 }
             }
         }
+
+        private static void TestPngEncoderCore<TPixel>(
+            TestImageProvider<TPixel> provider,
+            PngColorType pngColorType,
+            PngFilterMethod pngFilterMethod,
+            PngBitDepth bitDepth,
+            int compressionLevel = 6,
+            int paletteSize = 255,
+            bool appendPngColorType = false,
+            bool appendPngFilterMethod = false,
+            bool appendPixelType = false,
+            bool appendCompressionLevel = false,
+            bool appendPaletteSize = false,
+            bool appendPngBitDepth = false)
+        where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                var encoder = new PngEncoder
+                {
+                    ColorType = pngColorType,
+                    FilterMethod = pngFilterMethod,
+                    CompressionLevel = compressionLevel,
+                    BitDepth = bitDepth,
+                    Quantizer = new WuQuantizer(paletteSize)
+                };
+
+                string pngColorTypeInfo = appendPngColorType ? pngColorType.ToString() : string.Empty;
+                string pngFilterMethodInfo = appendPngFilterMethod ? pngFilterMethod.ToString() : string.Empty;
+                string compressionLevelInfo = appendCompressionLevel ? $"_C{compressionLevel}" : string.Empty;
+                string paletteSizeInfo = appendPaletteSize ? $"_PaletteSize-{paletteSize}" : string.Empty;
+                string pngBitDepthInfo = appendPngBitDepth ? bitDepth.ToString() : string.Empty;
+                string debugInfo = $"{pngColorTypeInfo}{pngFilterMethodInfo}{compressionLevelInfo}{paletteSizeInfo}{pngBitDepthInfo}";
+
+                string actualOutputFile = provider.Utility.SaveTestOutputFile(image, "png", encoder, debugInfo, appendPixelType);
+
+                // Compare to the Magick reference decoder.
+                IImageDecoder referenceDecoder = TestEnvironment.GetReferenceDecoder(actualOutputFile);
+
+                // We compare using both our decoder and the reference decoder as pixel transformation
+                // occurrs within the encoder itself leaving the input image unaffected.
+                // This means we are benefiting from testing our decoder also.
+                using (var imageSharpImage = Image.Load<TPixel>(actualOutputFile, new PngDecoder()))
+                using (var referenceImage = Image.Load<TPixel>(actualOutputFile, referenceDecoder))
+                {
+                    ImageComparer.Exact.VerifySimilarity(referenceImage, imageSharpImage);
+                }
+            }
+        }
     }
 }

tests/ImageSharp.Tests/Formats/Png/PngMetaDataTests.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Png;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Png
+{
+    public class PngMetaDataTests
+    {
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var meta = new PngMetaData()
+            {
+                BitDepth = PngBitDepth.Bit16,
+                ColorType = PngColorType.GrayscaleWithAlpha,
+                Gamma = 2
+            };
+            var clone = (PngMetaData)meta.DeepClone();
+
+            clone.BitDepth = PngBitDepth.Bit2;
+            clone.ColorType = PngColorType.Palette;
+            clone.Gamma = 1;
+
+            Assert.False(meta.BitDepth.Equals(clone.BitDepth));
+            Assert.False(meta.ColorType.Equals(clone.ColorType));
+            Assert.False(meta.Gamma.Equals(clone.Gamma));
+        }
+    }
+}

tests/ImageSharp.Tests/Helpers/ParallelHelperTests.cs

@@ -0,0 +1,338 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Collections.Concurrent;
+using System.Linq;
+using System.Numerics;
+using System.Threading;
+
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.Memory;
+using SixLabors.Primitives;
+
+using Xunit;
+using Xunit.Abstractions;
+
+namespace SixLabors.ImageSharp.Tests.Helpers
+{
+    public class ParallelHelperTests
+    {
+        private readonly ITestOutputHelper Output;
+        
+        public ParallelHelperTests(ITestOutputHelper output)
+        {
+            this.Output = output;
+        }
+
+        /// <summary>
+        /// maxDegreeOfParallelism, minY, maxY, expectedStepLength, expectedLastStepLength
+        /// </summary>
+        public static TheoryData<int, int, int, int, int> IterateRows_OverMinimumPixelsLimit_Data =
+            new TheoryData<int, int, int, int, int>()
+                {
+                    { 1, 0, 100, -1, 100 },
+                    { 2, 0, 9, 5, 4 },
+                    { 4, 0, 19, 5, 4 },
+                    { 2, 10, 19, 5, 4 },
+                    { 4, 0, 200, 50, 50 },
+                    { 4, 123, 323, 50, 50 },
+                    { 4, 0, 1201, 301, 298 },
+                    { 8, 10, 236, 29, 23 }
+                };
+
+        [Theory]
+        [MemberData(nameof(IterateRows_OverMinimumPixelsLimit_Data))]
+        public void IterateRows_OverMinimumPixelsLimit_IntervalsAreCorrect(
+            int maxDegreeOfParallelism,
+            int minY,
+            int maxY,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                1,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, minY, 10, maxY - minY);
+
+            int actualNumberOfSteps = 0;
+            
+            ParallelHelper.IterateRows(
+                rectangle,
+                parallelSettings,
+                rows =>
+                    {
+                        Assert.True(rows.Min >= minY);
+                        Assert.True(rows.Max <= maxY);
+
+                        int step = rows.Max - rows.Min;
+                        int expected = rows.Max < maxY ? expectedStepLength : expectedLastStepLength;
+
+                        Interlocked.Increment(ref actualNumberOfSteps);
+                        Assert.Equal(expected, step);
+                    });
+
+            Assert.Equal(maxDegreeOfParallelism, actualNumberOfSteps);
+        }
+
+        [Theory]
+        [MemberData(nameof(IterateRows_OverMinimumPixelsLimit_Data))]
+        public void IterateRows_OverMinimumPixelsLimit_ShouldVisitAllRows(
+            int maxDegreeOfParallelism,
+            int minY,
+            int maxY,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                1,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, minY, 10, maxY - minY);
+
+
+            int[] expectedData = Enumerable.Repeat(0, minY).Concat(Enumerable.Range(minY, maxY - minY)).ToArray();
+            int[] actualData = new int[maxY];
+
+            ParallelHelper.IterateRows(
+                rectangle,
+                parallelSettings,
+                rows =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            actualData[y] = y;
+                        }
+                    });
+            
+            Assert.Equal(expectedData, actualData);
+        }
+
+        [Theory]
+        [MemberData(nameof(IterateRows_OverMinimumPixelsLimit_Data))]
+        public void IterateRowsWithTempBuffer_OverMinimumPixelsLimit(
+            int maxDegreeOfParallelism,
+            int minY,
+            int maxY,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                1,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, minY, 10, maxY - minY);
+
+            var bufferHashes = new ConcurrentBag<int>();
+
+            int actualNumberOfSteps = 0;
+            ParallelHelper.IterateRowsWithTempBuffer(
+                rectangle,
+                parallelSettings,
+                (RowInterval rows, Memory<Vector4> buffer) =>
+                    {
+                        Assert.True(rows.Min >= minY);
+                        Assert.True(rows.Max <= maxY);
+
+                        bufferHashes.Add(buffer.GetHashCode());
+
+                        int step = rows.Max - rows.Min;
+                        int expected = rows.Max < maxY ? expectedStepLength : expectedLastStepLength;
+                        
+                        Interlocked.Increment(ref actualNumberOfSteps);
+                        Assert.Equal(expected, step);
+                    });
+
+            Assert.Equal(maxDegreeOfParallelism, actualNumberOfSteps);
+
+            int numberOfDifferentBuffers = bufferHashes.Distinct().Count();
+            Assert.Equal(actualNumberOfSteps, numberOfDifferentBuffers);
+        }
+
+        [Theory]
+        [MemberData(nameof(IterateRows_OverMinimumPixelsLimit_Data))]
+        public void IterateRowsWithTempBuffer_OverMinimumPixelsLimit_ShouldVisitAllRows(
+            int maxDegreeOfParallelism,
+            int minY,
+            int maxY,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                1,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, minY, 10, maxY - minY);
+
+            int[] expectedData = Enumerable.Repeat(0, minY).Concat(Enumerable.Range(minY, maxY - minY)).ToArray();
+            int[] actualData = new int[maxY];
+
+            ParallelHelper.IterateRowsWithTempBuffer(
+                rectangle,
+                parallelSettings,
+                (RowInterval rows, Memory<Vector4> buffer) =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            actualData[y] = y;
+                        }
+                    });
+
+            Assert.Equal(expectedData, actualData);
+
+        }
+
+        public static TheoryData<int, int, int, int, int, int, int> IterateRows_WithEffectiveMinimumPixelsLimit_Data =
+            new TheoryData<int, int, int, int, int, int, int>()
+                {
+                    { 2, 200, 50, 2, 1, -1, 2 },
+                    { 2, 200, 200, 1, 1, -1, 1 },
+                    { 4, 200, 100, 4, 2, 2, 2 },
+                    { 4, 300, 100, 8, 3, 3, 2 },
+                    { 2, 5000, 1, 4500, 1, -1, 4500 },
+                    { 2, 5000, 1, 5000, 1, -1, 5000 },
+                    { 2, 5000, 1, 5001, 2, 2501, 2500 },
+                };
+
+        [Theory]
+        [MemberData(nameof(IterateRows_WithEffectiveMinimumPixelsLimit_Data))]
+        public void IterateRows_WithEffectiveMinimumPixelsLimit(
+            int maxDegreeOfParallelism,
+            int minimumPixelsProcessedPerTask,
+            int width,
+            int height,
+            int expectedNumberOfSteps,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                minimumPixelsProcessedPerTask,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, 0, width, height);
+
+            int actualNumberOfSteps = 0;
+
+            ParallelHelper.IterateRows(
+                rectangle,
+                parallelSettings,
+                rows =>
+                    {
+                        Assert.True(rows.Min >= 0);
+                        Assert.True(rows.Max <= height);
+
+                        int step = rows.Max - rows.Min;
+                        int expected = rows.Max < height ? expectedStepLength : expectedLastStepLength;
+
+                        Interlocked.Increment(ref actualNumberOfSteps);
+                        Assert.Equal(expected, step);
+                    });
+
+            Assert.Equal(expectedNumberOfSteps, actualNumberOfSteps);
+        }
+
+        [Theory]
+        [MemberData(nameof(IterateRows_WithEffectiveMinimumPixelsLimit_Data))]
+        public void IterateRowsWithTempBuffer_WithEffectiveMinimumPixelsLimit(
+            int maxDegreeOfParallelism,
+            int minimumPixelsProcessedPerTask,
+            int width,
+            int height,
+            int expectedNumberOfSteps,
+            int expectedStepLength,
+            int expectedLastStepLength)
+        {
+            var parallelSettings = new ParallelExecutionSettings(
+                maxDegreeOfParallelism,
+                minimumPixelsProcessedPerTask,
+                Configuration.Default.MemoryAllocator);
+
+            var rectangle = new Rectangle(0, 0, width, height);
+            
+            int actualNumberOfSteps = 0;
+            ParallelHelper.IterateRowsWithTempBuffer(
+                rectangle,
+                parallelSettings,
+                (RowInterval rows, Memory<Vector4> buffer) =>
+                    {
+                        Assert.True(rows.Min >= 0);
+                        Assert.True(rows.Max <= height);
+
+                        int step = rows.Max - rows.Min;
+                        int expected = rows.Max < height ? expectedStepLength : expectedLastStepLength;
+
+                        Interlocked.Increment(ref actualNumberOfSteps);
+                        Assert.Equal(expected, step);
+                    });
+
+            Assert.Equal(expectedNumberOfSteps, actualNumberOfSteps);
+        }
+
+        public static readonly TheoryData<int, int, int, int, int, int, int> IterateRectangularBuffer_Data =
+            new TheoryData<int, int, int, int, int, int, int>()
+                {
+                    { 8, 582, 453, 10, 10, 291, 226 }, // boundary data from DetectEdgesTest.DetectEdges_InBox
+                    { 2, 582, 453, 10, 10, 291, 226 },
+                    { 16, 582, 453, 10, 10, 291, 226 },
+                    { 16, 582, 453, 10, 10, 1, 226 },
+                    { 16, 1, 453, 0, 10, 1, 226 },
+                };
+
+        [Theory]
+        [MemberData(nameof(IterateRectangularBuffer_Data))]
+        public void IterateRectangularBuffer(
+            int maxDegreeOfParallelism,
+            int bufferWidth,
+            int bufferHeight,
+            int rectX,
+            int rectY,
+            int rectWidth,
+            int rectHeight)
+        {
+            MemoryAllocator memoryAllocator = Configuration.Default.MemoryAllocator;
+
+            using (Buffer2D<Point> expected = memoryAllocator.Allocate2D<Point>(bufferWidth, bufferHeight, AllocationOptions.Clean))
+            using (Buffer2D<Point> actual = memoryAllocator.Allocate2D<Point>(bufferWidth, bufferHeight, AllocationOptions.Clean))
+            {
+                var rect = new Rectangle(rectX, rectY, rectWidth, rectHeight);
+                
+                void FillRow(int y, Buffer2D<Point> buffer)
+                {
+                    for (int x = rect.Left; x < rect.Right; x++)
+                    {
+                        buffer[x, y] = new Point(x, y);
+                    }
+                }
+
+                // Fill Expected data:
+                for (int y = rectY; y < rect.Bottom; y++)
+                {
+                    FillRow(y, expected);
+                }
+
+                // Fill actual data using IterateRows:
+                var settings = new ParallelExecutionSettings(maxDegreeOfParallelism, memoryAllocator);
+
+                ParallelHelper.IterateRows(rect, settings,
+                    rows =>
+                        {
+                            this.Output.WriteLine(rows.ToString());
+                            for (int y = rows.Min; y < rows.Max; y++)
+                            {
+                                FillRow(y, actual);
+                            }
+                        });
+
+                // Assert:
+                TestImageExtensions.CompareBuffers(expected.Span, actual.Span);
+            }
+        }
+    }
+}

tests/ImageSharp.Tests/Helpers/RowIntervalTests.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Runtime.CompilerServices;
+
+using SixLabors.ImageSharp.Memory;
+using SixLabors.Memory;
+
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Helpers
+{
+    public class RowIntervalTests
+    {
+        [Theory]
+        [InlineData(10, 20, 5, 10)]
+        [InlineData(1, 10, 0, 10)]
+        [InlineData(1, 10, 5, 8)]
+        [InlineData(1, 1, 0, 1)]
+        [InlineData(10, 20, 9, 10)]
+        [InlineData(10, 20, 0, 1)]
+        public void GetMultiRowSpan(int width, int height, int min, int max)
+        {
+            using (Buffer2D<int> buffer = Configuration.Default.MemoryAllocator.Allocate2D<int>(width, height))
+            {
+                var rows = new RowInterval(min, max);
+
+                Span<int> span = buffer.GetMultiRowSpan(rows);
+                
+                ref int expected0 = ref buffer.Span[min * width];
+                int expectedLength = (max - min) * width;
+
+                ref int actual0 = ref span[0];
+
+                Assert.Equal(span.Length, expectedLength);
+                Assert.True(Unsafe.AreSame(ref expected0, ref actual0));
+            }
+        }
+    }
+}

tests/ImageSharp.Tests/Image/ImageTests.WrapMemory.cs

@@ -84,7 +84,7 @@ namespace SixLabors.ImageSharp.Tests
             [Fact]
             public void WrapMemory_CreatedImageIsCorrect()
             {
-                Configuration cfg = Configuration.Default.ShallowCopy();
+                Configuration cfg = Configuration.Default.Clone();
                 var metaData = new ImageMetaData();
 
                 var array = new Rgba32[25];

tests/ImageSharp.Tests/Image/ImageTests.cs

@@ -32,7 +32,7 @@ namespace SixLabors.ImageSharp.Tests
             [Fact]
             public void Configuration_Width_Height()
             {
-                Configuration configuration = Configuration.Default.ShallowCopy();
+                Configuration configuration = Configuration.Default.Clone();
 
                 using (var image = new Image<Rgba32>(configuration, 11, 23))
                 {
@@ -48,7 +48,7 @@ namespace SixLabors.ImageSharp.Tests
             [Fact]
             public void Configuration_Width_Height_BackroundColor()
             {
-                Configuration configuration = Configuration.Default.ShallowCopy();
+                Configuration configuration = Configuration.Default.Clone();
                 Rgba32 color = Rgba32.Aquamarine;
 
                 using (var image = new Image<Rgba32>(configuration, 11, 23, color))

tests/ImageSharp.Tests/MetaData/ImageFrameMetaDataTests.cs

@@ -32,5 +32,13 @@ namespace SixLabors.ImageSharp.Tests
             Assert.Equal(colorTableLength, cloneGifFrameMetaData.ColorTableLength);
             Assert.Equal(disposalMethod, cloneGifFrameMetaData.DisposalMethod);
         }
+
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var metaData = new ImageFrameMetaData();
+            ImageFrameMetaData clone = metaData.DeepClone();
+            Assert.False(metaData.GetFormatMetaData(GifFormat.Instance).Equals(clone.GetFormatMetaData(GifFormat.Instance)));
+        }
     }
 }

tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
+using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
 using SixLabors.ImageSharp.PixelFormats;
@@ -29,7 +29,7 @@ namespace SixLabors.ImageSharp.Tests
             metaData.VerticalResolution = 2;
             metaData.Properties.Add(imageProperty);
 
-            ImageMetaData clone = metaData.Clone();
+            ImageMetaData clone = metaData.DeepClone();
 
             Assert.Equal(exifProfile.ToByteArray(), clone.ExifProfile.ToByteArray());
             Assert.Equal(4, clone.HorizontalResolution);
@@ -37,19 +37,43 @@ namespace SixLabors.ImageSharp.Tests
             Assert.Equal(imageProperty, clone.Properties[0]);
         }
 
+        [Fact]
+        public void CloneIsDeep()
+        {
+            var metaData = new ImageMetaData();
+
+            var exifProfile = new ExifProfile();
+            var imageProperty = new ImageProperty("name", "value");
+
+            metaData.ExifProfile = exifProfile;
+            metaData.HorizontalResolution = 4;
+            metaData.VerticalResolution = 2;
+            metaData.Properties.Add(imageProperty);
+
+            ImageMetaData clone = metaData.DeepClone();
+            clone.HorizontalResolution = 2;
+            clone.VerticalResolution = 4;
+
+            Assert.False(metaData.ExifProfile.Equals(clone.ExifProfile));
+            Assert.False(metaData.HorizontalResolution.Equals(clone.HorizontalResolution));
+            Assert.False(metaData.VerticalResolution.Equals(clone.VerticalResolution));
+            Assert.False(metaData.Properties.Equals(clone.Properties));
+            Assert.False(metaData.GetFormatMetaData(GifFormat.Instance).Equals(clone.GetFormatMetaData(GifFormat.Instance)));
+        }
+
         [Fact]
         public void HorizontalResolution()
         {
             var metaData = new ImageMetaData();
             Assert.Equal(96, metaData.HorizontalResolution);
 
-            metaData.HorizontalResolution=0;
+            metaData.HorizontalResolution = 0;
             Assert.Equal(96, metaData.HorizontalResolution);
 
-            metaData.HorizontalResolution=-1;
+            metaData.HorizontalResolution = -1;
             Assert.Equal(96, metaData.HorizontalResolution);
 
-            metaData.HorizontalResolution=1;
+            metaData.HorizontalResolution = 1;
             Assert.Equal(1, metaData.HorizontalResolution);
         }
 

tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs

@@ -67,16 +67,16 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void ConstructorCopy()
         {
-            Assert.Throws<ArgumentNullException>(() => { new ExifProfile((ExifProfile)null); });
+            Assert.Throws<NullReferenceException>(() => ((ExifProfile)null).DeepClone());
 
             ExifProfile profile = GetExifProfile();
 
-            var clone = new ExifProfile(profile);
+            ExifProfile clone = profile.DeepClone();
             TestProfile(clone);
 
             profile.SetValue(ExifTag.ColorSpace, (ushort)2);
 
-            clone = new ExifProfile(profile);
+            clone = profile.DeepClone();
             TestProfile(clone);
         }
 
@@ -234,10 +234,12 @@ namespace SixLabors.ImageSharp.Tests
             exifProfile.SetValue(ExifTag.XResolution, new Rational(200));
             exifProfile.SetValue(ExifTag.YResolution, new Rational(300));
 
-            var metaData = new ImageMetaData();
-            metaData.ExifProfile = exifProfile;
-            metaData.HorizontalResolution = 200;
-            metaData.VerticalResolution = 300;
+            var metaData = new ImageMetaData
+            {
+                ExifProfile = exifProfile,
+                HorizontalResolution = 200,
+                VerticalResolution = 300
+            };
 
             metaData.HorizontalResolution = 100;
 
@@ -355,11 +357,11 @@ namespace SixLabors.ImageSharp.Tests
 
             // act
             Image<Rgba32> reloadedImage = WriteAndRead(image, imageFormat);
-            
+
             // assert
             ExifProfile actual = reloadedImage.MetaData.ExifProfile;
             Assert.NotNull(actual);
-            foreach(KeyValuePair<ExifTag, object> expectedProfileValue in TestProfileValues)
+            foreach (KeyValuePair<ExifTag, object> expectedProfileValue in TestProfileValues)
             {
                 ExifValue actualProfileValue = actual.GetValue(expectedProfileValue.Key);
                 Assert.NotNull(actualProfileValue);
@@ -371,7 +373,7 @@ namespace SixLabors.ImageSharp.Tests
         public void ProfileToByteArray()
         {
             // arrange
-            byte[] exifBytesWithExifCode = ProfileResolver.ExifMarker.Concat(ExifConstants.LittleEndianByteOrderMarker).ToArray(); 
+            byte[] exifBytesWithExifCode = ProfileResolver.ExifMarker.Concat(ExifConstants.LittleEndianByteOrderMarker).ToArray();
             byte[] exifBytesWithoutExifCode = ExifConstants.LittleEndianByteOrderMarker;
             ExifProfile expectedProfile = CreateExifProfile();
             var expectedProfileTags = expectedProfile.Values.Select(x => x.Tag).ToList();
@@ -384,7 +386,7 @@ namespace SixLabors.ImageSharp.Tests
             Assert.NotNull(actualBytes);
             Assert.NotEmpty(actualBytes);
             Assert.Equal(exifBytesWithoutExifCode, actualBytes.Take(exifBytesWithoutExifCode.Length).ToArray());
-            foreach(ExifTag expectedProfileTag in expectedProfileTags)
+            foreach (ExifTag expectedProfileTag in expectedProfileTags)
             {
                 ExifValue actualProfileValue = actualProfile.GetValue(expectedProfileTag);
                 ExifValue expectedProfileValue = expectedProfile.GetValue(expectedProfileTag);
@@ -396,7 +398,7 @@ namespace SixLabors.ImageSharp.Tests
         {
             var profile = new ExifProfile();
 
-            foreach(KeyValuePair<ExifTag, object> exifProfileValue in TestProfileValues)
+            foreach (KeyValuePair<ExifTag, object> exifProfileValue in TestProfileValues)
             {
                 profile.SetValue(exifProfileValue.Key, exifProfileValue.Value);
             }
@@ -416,7 +418,7 @@ namespace SixLabors.ImageSharp.Tests
 
         private static Image<Rgba32> WriteAndRead(Image<Rgba32> image, TestImageWriteFormat imageFormat)
         {
-            switch(imageFormat)
+            switch (imageFormat)
             {
                 case TestImageWriteFormat.Jpeg:
                     return WriteAndReadJpeg(image);

tests/ImageSharp.Tests/Processing/Processors/Convolution/DetectEdgesTest.cs

@@ -10,8 +10,6 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Convolution
 {
-    using SixLabors.ImageSharp.Advanced;
-
     public class DetectEdgesTest : FileTestBase
     {
         private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.0456F);

tests/ImageSharp.Tests/Processing/Processors/Transforms/CropTest.cs

@@ -1,24 +1,34 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
+
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
+using SixLabors.Primitives;
+
 using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 {
+    [GroupOutput("Transforms")]
     public class CropTest : FileTestBase
     {
         [Theory]
-        [WithFileCollection(nameof(DefaultFiles), DefaultPixelType)]
-        public void ImageShouldCrop<TPixel>(TestImageProvider<TPixel> provider)
+        [WithTestPatternImages(70, 30, PixelTypes.Rgba32, 0, 0, 70, 30)]
+        [WithTestPatternImages(50, 50, PixelTypes.Rgba32, -1, -1, 100, 200)]
+        [WithTestPatternImages(30, 70, PixelTypes.Rgba32, 7, 13, 20, 50)]
+        public void Crop<TPixel>(TestImageProvider<TPixel> provider, int x, int y, int w, int h)
             where TPixel : struct, IPixel<TPixel>
         {
-            using (Image<TPixel> image = provider.GetImage())
-            {
-                image.Mutate(x => x.Crop(image.Width / 2, image.Height / 2));
-                image.DebugSave(provider);
-            }
+            var rect = new Rectangle(x, y, w, h);
+            FormattableString info = $"X{x}Y{y}.W{w}H{h}";
+            provider.RunValidatingProcessorTest(
+                ctx => ctx.Crop(rect),
+                info,
+                appendPixelTypeToFileName: false,
+                comparer: ImageComparer.Exact);
         }
     }
 }

tests/ImageSharp.Tests/Processing/Processors/Transforms/FlipTests.cs

@@ -5,23 +5,24 @@ using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 
 using Xunit;
+
 // ReSharper disable InconsistentNaming
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 {
-    using SixLabors.ImageSharp.Processing;
-
+    [GroupOutput("Transforms")]
     public class FlipTests
     {
-        public static readonly TheoryData<FlipMode> FlipValues
-            = new TheoryData<FlipMode>
-        {
-            { FlipMode.None },
-            { FlipMode.Vertical },
-            { FlipMode.Horizontal },
-        };
+        public static readonly TheoryData<FlipMode> FlipValues =
+            new TheoryData<FlipMode>
+                {
+                    FlipMode.None,
+                    FlipMode.Vertical,
+                    FlipMode.Horizontal,
+                };
 
         [Theory]
+        [WithTestPatternImages(nameof(FlipValues), 20, 37, PixelTypes.Rgba32)]
         [WithTestPatternImages(nameof(FlipValues), 53, 37, PixelTypes.Rgba32)]
         [WithTestPatternImages(nameof(FlipValues), 17, 32, PixelTypes.Rgba32)]
         public void Flip<TPixel>(TestImageProvider<TPixel> provider, FlipMode flipMode)

tests/ImageSharp.Tests/Processing/Processors/Transforms/RotateTests.cs

@@ -7,7 +7,8 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 {
-    public class RotateTests : FileTestBase
+    [GroupOutput("Transforms")]
+    public class RotateTests
     {
         public static readonly TheoryData<float> RotateAngles
             = new TheoryData<float>
@@ -25,29 +26,21 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
         };
 
         [Theory]
-        [WithTestPatternImages(nameof(RotateAngles), 100, 50, DefaultPixelType)]
-        [WithTestPatternImages(nameof(RotateAngles), 50, 100, DefaultPixelType)]
+        [WithTestPatternImages(nameof(RotateAngles), 100, 50, PixelTypes.Rgba32)]
+        [WithTestPatternImages(nameof(RotateAngles), 50, 100, PixelTypes.Rgba32)]
         public void Rotate_WithAngle<TPixel>(TestImageProvider<TPixel> provider, float value)
             where TPixel : struct, IPixel<TPixel>
         {
-            using (Image<TPixel> image = provider.GetImage())
-            {
-                image.Mutate(x => x.Rotate(value));
-                image.DebugSave(provider, value);
-            }
+            provider.RunValidatingProcessorTest(ctx => ctx.Rotate(value), value, appendPixelTypeToFileName: false);
         }
 
         [Theory]
-        [WithTestPatternImages(nameof(RotateEnumValues), 100, 50, DefaultPixelType)]
-        [WithTestPatternImages(nameof(RotateEnumValues), 50, 100, DefaultPixelType)]
+        [WithTestPatternImages(nameof(RotateEnumValues), 100, 50, PixelTypes.Rgba32)]
+        [WithTestPatternImages(nameof(RotateEnumValues), 50, 100, PixelTypes.Rgba32)]
         public void Rotate_WithRotateTypeEnum<TPixel>(TestImageProvider<TPixel> provider, RotateMode value)
             where TPixel : struct, IPixel<TPixel>
         {
-            using (Image<TPixel> image = provider.GetImage())
-            {
-                image.Mutate(x => x.Rotate(value));
-                image.DebugSave(provider, value);
-            }
+            provider.RunValidatingProcessorTest(ctx => ctx.Rotate(value), value, appendPixelTypeToFileName: false);
         }
     }
 }

tests/ImageSharp.Tests/Processing/Transforms/ProjectiveTransformTests.cs

@@ -20,7 +20,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         private static readonly ImageComparer TolerantComparer = ImageComparer.TolerantPercentage(0.5f, 3);
 
         private ITestOutputHelper Output { get; }
-
+        
         public static readonly TheoryData<string> ResamplerNames = new TheoryData<string>
         {
             nameof(KnownResamplers.Bicubic),

tests/ImageSharp.Tests/TestUtilities/ImageProviders/TestImageProvider.cs

@@ -33,7 +33,7 @@ namespace SixLabors.ImageSharp.Tests
 
         public virtual string SourceFileOrDescription => "";
 
-        public Configuration Configuration { get; set; } = Configuration.Default.ShallowCopy();
+        public Configuration Configuration { get; set; } = Configuration.Default.Clone();
 
         /// <summary>
         /// Utility instance to provide informations about the test image & manage input/output

tests/ImageSharp.Tests/TestUtilities/ReferenceCodecs/MagickReferenceDecoder.cs

@@ -29,13 +29,13 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs
                 {
                     if (magickImage.Depth == 8)
                     {
-                        byte[] data = pixels.ToByteArray("RGBA");
-                        
+                        byte[] data = pixels.ToByteArray(PixelMapping.RGBA);
+
                         PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(data, resultPixels, resultPixels.Length);
                     }
                     else if (magickImage.Depth == 16)
                     {
-                        ushort[] data = pixels.ToShortArray("RGBA");
+                        ushort[] data = pixels.ToShortArray(PixelMapping.RGBA);
                         Span<byte> bytes = MemoryMarshal.Cast<ushort, byte>(data.AsSpan());
 
                         PixelOperations<TPixel>.Instance.PackFromRgba64Bytes(bytes, resultPixels, resultPixels.Length);

tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs

@@ -441,14 +441,23 @@ namespace SixLabors.ImageSharp.Tests
         {
             Span<TPixel> actualPixels = image.GetPixelSpan();
 
-            Assert.True(expectedPixels.Length == actualPixels.Length, "Buffer sizes are not equal!");
+            CompareBuffers(expectedPixels, actualPixels);
 
-            for (int i = 0; i < expectedPixels.Length; i++)
+            return image;
+        }
+
+        public static void CompareBuffers<T>(Span<T> expected, Span<T> actual)
+            where T : struct, IEquatable<T>
+        {
+            Assert.True(expected.Length == actual.Length, "Buffer sizes are not equal!");
+
+            for (int i = 0; i < expected.Length; i++)
             {
-                Assert.True(expectedPixels[i].Equals(actualPixels[i]), $"Pixels are different on position {i}!");
-            }
+                T x = expected[i];
+                T a = actual[i];
 
-            return image;
+                Assert.True(x.Equals(a), $"Buffers differ at position {i}! Expected: {x} | Actual: {a}");
+            }
         }
 
         /// <summary>

tests/ImageSharp.Tests/TestUtilities/Tests/MagickReferenceCodecTests.cs

@@ -14,10 +14,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.Tests
 
     public class MagickReferenceCodecTests
     {
-        public MagickReferenceCodecTests(ITestOutputHelper output)
-        {
-            this.Output = output;
-        }
+        public MagickReferenceCodecTests(ITestOutputHelper output) => this.Output = output;
 
         private ITestOutputHelper Output { get; }
 
@@ -61,6 +58,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.Tests
         [WithBlankImages(1, 1, PixelTypesToTest48, TestImages.Png.Rgb48Bpp)]
         [WithBlankImages(1, 1, PixelTypesToTest48, TestImages.Png.Rgb48BppInterlaced)]
         [WithBlankImages(1, 1, PixelTypesToTest48, TestImages.Png.Rgb48BppTrans)]
+        [WithBlankImages(1, 1, PixelTypesToTest48, TestImages.Png.Gray16Bit)]
         public void MagickDecode_16BitDepthImage_IsApproximatelyEquivalentTo_SystemDrawingResult<TPixel>(TestImageProvider<TPixel> dummyProvider, string testImage)
             where TPixel : struct, IPixel<TPixel>
         {
@@ -71,7 +69,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.Tests
 
             // 1020 == 4 * 255 (Equivalent to manhattan distance of 1+1+1+1=4 in Rgba32 space)
             var comparer = ImageComparer.TolerantPercentage(1, 1020);
-            
+
             using (var mImage = Image.Load<TPixel>(path, magickDecoder))
             using (var sdImage = Image.Load<TPixel>(path, sdDecoder))
             {

tests/ImageSharp.Tests/TestUtilities/Tests/ReferenceDecoderBenchmarks.cs

@@ -17,7 +17,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.Tests
         private ITestOutputHelper Output { get; }
 
         public const string SkipBenchmarks =
-#if false
+#if true
             "Benchmark, enable manually!";
 #else
             null;

tests/Images/External

@@ -1 +1 @@
-Subproject commit 6abc3bc0ac253a24c9e88e68d7b7d853350a85da
+Subproject commit 7f4d2d64c6b820ca2b6827e6a8540a1013305ccf