Merge pull request #506 from carbon/master

Improve Code Quality

src/ImageSharp/ColorSpaces/CieLab.cs

@@ -23,7 +23,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         /// <summary>
         /// Represents a <see cref="CieLab"/> that has L, A, B values set to zero.
         /// </summary>
-        public static readonly CieLab Empty = default(CieLab);
+        public static readonly CieLab Empty = default;
 
         /// <summary>
         /// The backing vector for SIMD support.

src/ImageSharp/ColorSpaces/CieLch.cs

@@ -194,12 +194,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieLch)
+            return obj is CieLch other && this.Equals(other);
-            {
-                return this.Equals((CieLch)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/CieLchuv.cs

@@ -194,12 +194,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieLchuv)
+            return obj is CieLchuv other && this.Equals(other);
-            {
-                return this.Equals((CieLchuv)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/CieLuv.cs

@@ -196,12 +196,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieLuv)
+            return obj is CieLuv other && this.Equals(other);
-            {
-                return this.Equals((CieLuv)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/CieXyChromaticityCoordinates.cs

@@ -132,12 +132,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieXyChromaticityCoordinates)
+            return obj is CieXyChromaticityCoordinates other && this.Equals(other);
-            {
-                return this.Equals((CieXyChromaticityCoordinates)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/CieXyy.cs

@@ -148,12 +148,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieXyy)
+            return obj is CieXyy other && this.Equals(other);
-            {
-                return this.Equals((CieXyy)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/CieXyz.cs

@@ -148,12 +148,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is CieXyz)
+            return obj is CieXyz other && this.Equals(other);
-            {
-                return this.Equals((CieXyz)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Cmyk.cs

@@ -150,12 +150,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is Cmyk)
+            return obj is Cmyk other && this.Equals(other);
-            {
-                return this.Equals((Cmyk)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLab/CieLabToCieXyzConverter.cs

@@ -15,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLabColor
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieXyz Convert(CieLab input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here: http://www.brucelindbloom.com/index.html?Eqn_Lab_to_XYZ.html
             float l = input.L, a = input.A, b = input.B;
             float fy = (l + 16) / 116F;

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLab/CieXyzToCieLabConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLabColorSapce
 {
@@ -44,8 +43,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLabColor
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieLab Convert(CieXyz input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here: http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_Lab.html
             float wx = this.LabWhitePoint.X, wy = this.LabWhitePoint.Y, wz = this.LabWhitePoint.Z;
 

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLch/CIeLchToCieLabConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchColorSapce
 {
@@ -16,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchColor
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieLab Convert(CieLch input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here:
             // https://en.wikipedia.org/wiki/Lab_color_space#Cylindrical_representation:_CIELCh_or_CIEHLC
             float l = input.L, c = input.C, hDegrees = input.H;

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLch/CieLabToCieLchConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchColorSapce
 {
@@ -16,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchColor
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieLch Convert(CieLab input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here:
             // https://en.wikipedia.org/wiki/Lab_color_space#Cylindrical_representation:_CIELCh_or_CIEHLC
             float l = input.L, a = input.A, b = input.B;

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLchuv/CieLchuvToCieLuvConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchuvColorSapce
 {
@@ -16,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchuvCol
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieLuv Convert(CieLchuv input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here:
             // https://en.wikipedia.org/wiki/CIELUV#Cylindrical_representation_.28CIELCH.29
             float l = input.L, c = input.C, hDegrees = input.H;

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLchuv/CieLuvToCieLchuvConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchuvColorSapce
 {
@@ -16,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLchuvCol
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieLchuv Convert(CieLuv input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here:
             // https://en.wikipedia.org/wiki/CIELUV#Cylindrical_representation_.28CIELCH.29
             float l = input.L, a = input.U, b = input.V;

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLuv/CieLuvToCieXyzConverter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.ColorSpaces;
 
 namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLuvColorSapce
 {
@@ -16,8 +15,6 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.CieLuvColor
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public CieXyz Convert(CieLuv input)
         {
-            DebugGuard.NotNull(input, nameof(input));
-
             // Conversion algorithm described here: http://www.brucelindbloom.com/index.html?Eqn_Luv_to_XYZ.html
             float l = input.L, u = input.U, v = input.V;
 

src/ImageSharp/ColorSpaces/Conversion/Implementation/Rgb/RGBPrimariesChromaticityCoordinates.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.RgbColorSap
     /// Represents the chromaticity coordinates of RGB primaries.
     /// One of the specifiers of <see cref="IRgbWorkingSpace"/>.
     /// </summary>
-    internal struct RgbPrimariesChromaticityCoordinates : IEquatable<RgbPrimariesChromaticityCoordinates>
+    internal readonly struct RgbPrimariesChromaticityCoordinates : IEquatable<RgbPrimariesChromaticityCoordinates>
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="RgbPrimariesChromaticityCoordinates"/> struct.
@@ -76,12 +76,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.RgbColorSap
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (obj is RgbPrimariesChromaticityCoordinates)
+            return obj is RgbPrimariesChromaticityCoordinates other && this.Equals(other);
-            {
-                return this.Equals((RgbPrimariesChromaticityCoordinates)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Conversion/Implementation/Rgb/RgbWorkingSpace.cs

@@ -73,12 +73,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.RgbColorSap
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (obj is RgbWorkingSpace)
+            return obj is RgbWorkingSpace other && this.Equals(other);
-            {
-                return this.Equals((RgbWorkingSpace)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Hsl.cs

@@ -150,12 +150,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is Hsl)
+            return obj is Hsl other && this.Equals(other);
-            {
-                return this.Equals((Hsl)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Hsv.cs

@@ -202,12 +202,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is Hsv)
+            return obj is Hsv other && this.Equals(other);
-            {
-                return this.Equals((Hsv)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/HunterLab.cs

@@ -190,12 +190,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is HunterLab)
+            return obj is HunterLab other && this.Equals(other);
-            {
-                return this.Equals((HunterLab)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/LinearRgb.cs

@@ -182,12 +182,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is LinearRgb)
+            return obj is LinearRgb other && this.Equals(other);
-            {
-                return this.Equals((LinearRgb)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Lms.cs

@@ -149,12 +149,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is Lms)
+            return obj is Lms other && this.Equals(other);
-            {
-                return this.Equals((Lms)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/Rgb.cs

@@ -204,12 +204,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is Rgb)
+            return obj is Rgb other && this.Equals(other);
-            {
-                return this.Equals((Rgb)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/ColorSpaces/YCbCr.cs

@@ -152,12 +152,7 @@ namespace SixLabors.ImageSharp.ColorSpaces
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public override bool Equals(object obj)
         {
-            if (obj is YCbCr)
+            return obj is YCbCr other && this.Equals(other);
-            {
-                return this.Equals((YCbCr)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>

src/ImageSharp/Formats/Bmp/BmpBitsPerPixel.cs

@@ -16,6 +16,6 @@ namespace SixLabors.ImageSharp.Formats.Bmp
         /// <summary>
         /// 32 bits per pixel. Each pixel consists of 4 bytes.
         /// </summary>
-        Pixel32 = 4,
+        Pixel32 = 4
     }
 }

src/ImageSharp/Formats/Bmp/BmpDecoder.cs

@@ -28,7 +28,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
 
             where TPixel : struct, IPixel<TPixel>
         {
-            Guard.NotNull(stream, "stream");
+            Guard.NotNull(stream, nameof(stream));
 
             return new BmpDecoderCore(configuration, this).Decode<TPixel>(stream);
         }
@@ -36,7 +36,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
         /// <inheritdoc/>
         public IImageInfo Identify(Configuration configuration, Stream stream)
         {
-            Guard.NotNull(stream, "stream");
+            Guard.NotNull(stream, nameof(stream));
 
             return new BmpDecoderCore(configuration, this).Identify(stream);
         }

src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs

@@ -224,7 +224,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
             var color = default(TPixel);
             var rgba = new Rgba32(0, 0, 0, 255);
 
-            using (var buffer = this.memoryManager.AllocateClean2D<byte>(width, height))
+            using (Buffer2D<byte> buffer = this.memoryManager.AllocateClean2D<byte>(width, height))
             {
                 this.UncompressRle8(width, buffer.Span);
 
@@ -398,7 +398,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
             var color = default(TPixel);
             var rgba = new Rgba32(0, 0, 0, 255);
 
-            using (var buffer = this.memoryManager.AllocateManagedByteBuffer(stride))
+            using (IManagedByteBuffer buffer = this.memoryManager.AllocateManagedByteBuffer(stride))
             {
                 for (int y = 0; y < height; y++)
                 {
@@ -581,13 +581,11 @@ namespace SixLabors.ImageSharp.Formats.Bmp
 
             this.currentStream.Read(data, 0, BmpFileHeader.Size);
 
-            this.fileHeader = new BmpFileHeader
+            this.fileHeader = new BmpFileHeader(
-            {
+                type: BitConverter.ToInt16(data, 0),
-                Type = BitConverter.ToInt16(data, 0),
+                fileSize: BitConverter.ToInt32(data, 2),
-                FileSize = BitConverter.ToInt32(data, 2),
+                reserved: BitConverter.ToInt32(data, 6),
-                Reserved = BitConverter.ToInt32(data, 6),
+                offset: BitConverter.ToInt32(data, 10));
-                Offset = BitConverter.ToInt32(data, 10)
-            };
         }
 
         /// <summary>

src/ImageSharp/Formats/Bmp/BmpEncoder.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
-using System.Collections.Generic;
 using System.IO;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.PixelFormats;

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -55,9 +55,9 @@ namespace SixLabors.ImageSharp.Formats.Bmp
             this.padding = bytesPerLine - (image.Width * (int)this.bitsPerPixel);
 
             // Do not use IDisposable pattern here as we want to preserve the stream.
-            EndianBinaryWriter writer = new EndianBinaryWriter(Endianness.LittleEndian, stream);
+            var writer = new EndianBinaryWriter(Endianness.LittleEndian, stream);
 
-            BmpInfoHeader infoHeader = new BmpInfoHeader
+            var infoHeader = new BmpInfoHeader
             {
                 HeaderSize = BmpInfoHeader.BitmapInfoHeaderSize,
                 Height = image.Height,
@@ -69,12 +69,11 @@ namespace SixLabors.ImageSharp.Formats.Bmp
                 ClrImportant = 0
             };
 
-            BmpFileHeader fileHeader = new BmpFileHeader
+            var fileHeader = new BmpFileHeader(
-            {
+                type: 19778, // BM
-                Type = 19778, // BM
+                offset: 54,
-                Offset = 54,
+                reserved: 0,
-                FileSize = 54 + infoHeader.ImageSize
+                fileSize: 54 + infoHeader.ImageSize);
-            };
 
             WriteHeader(writer, fileHeader);
             this.WriteInfo(writer, infoHeader);
@@ -92,7 +91,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
         /// <param name="fileHeader">
         /// The <see cref="BmpFileHeader"/> containing the header data.
         /// </param>
-        private static void WriteHeader(EndianBinaryWriter writer, BmpFileHeader fileHeader)
+        private static void WriteHeader(EndianBinaryWriter writer, in BmpFileHeader fileHeader)
         {
             writer.Write(fileHeader.Type);
             writer.Write(fileHeader.FileSize);

src/ImageSharp/Formats/Bmp/BmpFileHeader.cs

@@ -13,35 +13,43 @@ namespace SixLabors.ImageSharp.Formats.Bmp
     /// All of the other integer values are stored in little-endian format
     /// (i.e. least-significant byte first).
     /// </remarks>
-    internal sealed class BmpFileHeader
+    internal readonly struct BmpFileHeader
     {
         /// <summary>
         /// Defines of the data structure in the bitmap file.
         /// </summary>
         public const int Size = 14;
 
+        public BmpFileHeader(short type, int fileSize, int reserved, int offset)
+        {
+            this.Type = type;
+            this.FileSize = fileSize;
+            this.Reserved = reserved;
+            this.Offset = offset;
+        }
+
         /// <summary>
-        /// Gets or sets the Bitmap identifier.
+        /// Gets the Bitmap identifier.
         /// The field used to identify the bitmap file: 0x42 0x4D
         /// (Hex code points for B and M)
         /// </summary>
-        public short Type { get; set; }
+        public short Type { get; }
 
         /// <summary>
-        /// Gets or sets the size of the bitmap file in bytes.
+        /// Gets the size of the bitmap file in bytes.
         /// </summary>
-        public int FileSize { get; set; }
+        public int FileSize { get; }
 
         /// <summary>
-        /// Gets or sets any reserved data; actual value depends on the application
+        /// Gets any reserved data; actual value depends on the application
         /// that creates the image.
         /// </summary>
-        public int Reserved { get; set; }
+        public int Reserved { get;  }
 
         /// <summary>
-        /// Gets or sets the offset, i.e. starting address, of the byte where
+        /// Gets the offset, i.e. starting address, of the byte where
         /// the bitmap data can be found.
         /// </summary>
-        public int Offset { get; set; }
+        public int Offset { get; }
     }
 }

src/ImageSharp/Formats/Gif/PackedField.cs

@@ -169,9 +169,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            PackedField? field = obj as PackedField?;
+            return obj is PackedField other && this.Equals(other);
-
-            return this.Byte == field?.Byte;
         }
 
         /// <inheritdoc/>

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

@@ -241,19 +241,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
         /// <inheritdoc />
         public override string ToString()
         {
-            var bld = new StringBuilder();
+            var sb = new StringBuilder();
-            bld.Append('[');
+            sb.Append('[');
             for (int i = 0; i < Size; i++)
             {
-                bld.Append(this[i]);
+                sb.Append(this[i]);
                 if (i < Size - 1)
                 {
-                    bld.Append(',');
+                    sb.Append(',');
                 }
             }
 
-            bld.Append(']');
+            sb.Append(']');
-            return bld.ToString();
+            return sb.ToString();
         }
 
         /// <inheritdoc />
@@ -273,12 +273,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj))
+            return obj is Block8x8 other && this.Equals(other);
-            {
-                return false;
-            }
-
-            return obj is Block8x8 && this.Equals((Block8x8)obj);
         }
 
         /// <inheritdoc />

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

@@ -496,19 +496,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
         /// <inheritdoc />
         public override string ToString()
         {
-            var bld = new StringBuilder();
+            var sb = new StringBuilder();
-            bld.Append('[');
+            sb.Append('[');
             for (int i = 0; i < Size; i++)
             {
-                bld.Append(this[i]);
+                sb.Append(this[i]);
                 if (i < Size - 1)
                 {
-                    bld.Append(',');
+                    sb.Append(',');
                 }
             }
 
-            bld.Append(']');
+            sb.Append(']');
-            return bld.ToString();
+            return sb.ToString();
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]

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

@@ -94,12 +94,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj))
+            return obj is AdobeMarker other && this.Equals(other);
-            {
-                return false;
-            }
-
-            return obj is AdobeMarker && this.Equals((AdobeMarker)obj);
         }
 
         /// <inheritdoc/>

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

@@ -87,7 +87,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
                 }
             }
 
-            marker = default(JFifMarker);
+            marker = default;
             return false;
         }
 
@@ -104,12 +104,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj))
+            return obj is JFifMarker other && this.Equals(other);
-            {
-                return false;
-            }
-
-            return obj is JFifMarker && this.Equals((JFifMarker)obj);
         }
 
         /// <inheritdoc/>

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

@@ -427,10 +427,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         {
             if (this.isExif)
             {
-                ExifValue horizontal = this.MetaData.ExifProfile.GetValue(ExifTag.XResolution);
+                double horizontalValue = this.MetaData.ExifProfile.TryGetValue(ExifTag.XResolution, out ExifValue horizonalTag)
-                ExifValue vertical = this.MetaData.ExifProfile.GetValue(ExifTag.YResolution);
+                    ? ((Rational)horizonalTag.Value).ToDouble()
-                double horizontalValue = horizontal != null ? ((Rational)horizontal.Value).ToDouble() : 0;
+                    : 0;
-                double verticalValue = vertical != null ? ((Rational)vertical.Value).ToDouble() : 0;
+
+                double verticalValue = this.MetaData.ExifProfile.TryGetValue(ExifTag.YResolution, out ExifValue verticalTag)
+                    ? ((Rational)verticalTag.Value).ToDouble()
+                    : 0;
 
                 if (horizontalValue > 0 && verticalValue > 0)
                 {

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

@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
     /// <summary>
     /// Represents a jpeg file marker
     /// </summary>
-    internal struct PdfJsFileMarker
+    internal readonly struct PdfJsFileMarker
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="PdfJsFileMarker"/> struct.
@@ -34,9 +34,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         }
 
         /// <summary>
-        /// Gets or sets a value indicating whether the current marker is invalid
+        /// Gets a value indicating whether the current marker is invalid
         /// </summary>
-        public bool Invalid { get; set; }
+        public bool Invalid { get; }
 
         /// <summary>
         /// Gets the position of the marker within a stream

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

@@ -380,10 +380,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         {
             if (this.isExif)
             {
-                ExifValue horizontal = image.MetaData.ExifProfile.GetValue(ExifTag.XResolution);
+                double horizontalValue = image.MetaData.ExifProfile.TryGetValue(ExifTag.XResolution, out ExifValue horizontalTag)
-                ExifValue vertical = image.MetaData.ExifProfile.GetValue(ExifTag.YResolution);
+                    ? ((Rational)horizontalTag.Value).ToDouble()
-                double horizontalValue = horizontal != null ? ((Rational)horizontal.Value).ToDouble() : 0;
+                    : 0;
-                double verticalValue = vertical != null ? ((Rational)vertical.Value).ToDouble() : 0;
+
+                double verticalValue = image.MetaData.ExifProfile.TryGetValue(ExifTag.YResolution, out ExifValue verticalTag)
+                    ? ((Rational)verticalTag.Value).ToDouble()
+                    : 0;
 
                 if (horizontalValue > 0 && verticalValue > 0)
                 {

src/ImageSharp/Formats/Png/PngChunk.cs

@@ -10,13 +10,18 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// </summary>
     internal sealed class PngChunk
     {
+        public PngChunk(int length)
+        {
+            this.Length = length;
+        }
+
         /// <summary>
-        /// Gets or sets the length.
+        /// Gets the length.
         /// An unsigned integer giving the number of bytes in the chunk's
         /// data field. The length counts only the data field, not itself,
         /// the chunk type code, or the CRC. Zero is a valid length
         /// </summary>
-        public int Length { get; set; }
+        public int Length { get; }
 
         /// <summary>
         /// Gets or sets the chunk type as string with 4 chars.

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -217,19 +217,18 @@ namespace SixLabors.ImageSharp.Formats.Png
             {
                 using (var deframeStream = new ZlibInflateStream(this.currentStream))
                 {
-                    PngChunk currentChunk;
+                    while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
-                    while (!this.isEndChunkReached && (currentChunk = this.ReadChunk()) != null)
                     {
                         try
                         {
-                            switch (currentChunk.Type)
+                            switch (chunk.Type)
                             {
                                 case PngChunkTypes.Header:
-                                    this.ReadHeaderChunk(currentChunk.Data.Array);
+                                    this.ReadHeaderChunk(chunk.Data.Array);
                                     this.ValidateHeader();
                                     break;
                                 case PngChunkTypes.Physical:
-                                    this.ReadPhysicalChunk(metadata, currentChunk.Data.Array);
+                                    this.ReadPhysicalChunk(metadata, chunk.Data.Array);
                                     break;
                                 case PngChunkTypes.Data:
                                     if (image == null)
@@ -237,23 +236,23 @@ namespace SixLabors.ImageSharp.Formats.Png
                                         this.InitializeImage(metadata, out image);
                                     }
 
-                                    deframeStream.AllocateNewBytes(currentChunk.Length);
+                                    deframeStream.AllocateNewBytes(chunk.Length);
                                     this.ReadScanlines(deframeStream.CompressedStream, image.Frames.RootFrame);
                                     this.currentStream.Read(this.crcBuffer, 0, 4);
                                     break;
                                 case PngChunkTypes.Palette:
-                                    byte[] pal = new byte[currentChunk.Length];
+                                    byte[] pal = new byte[chunk.Length];
-                                    Buffer.BlockCopy(currentChunk.Data.Array, 0, pal, 0, currentChunk.Length);
+                                    Buffer.BlockCopy(chunk.Data.Array, 0, pal, 0, chunk.Length);
                                     this.palette = pal;
                                     break;
                                 case PngChunkTypes.PaletteAlpha:
-                                    byte[] alpha = new byte[currentChunk.Length];
+                                    byte[] alpha = new byte[chunk.Length];
-                                    Buffer.BlockCopy(currentChunk.Data.Array, 0, alpha, 0, currentChunk.Length);
+                                    Buffer.BlockCopy(chunk.Data.Array, 0, alpha, 0, chunk.Length);
                                     this.paletteAlpha = alpha;
                                     this.AssignTransparentMarkers(alpha);
                                     break;
                                 case PngChunkTypes.Text:
-                                    this.ReadTextChunk(metadata, currentChunk.Data.Array, currentChunk.Length);
+                                    this.ReadTextChunk(metadata, chunk.Data.Array, chunk.Length);
                                     break;
                                 case PngChunkTypes.End:
                                     this.isEndChunkReached = true;
@@ -263,10 +262,10 @@ namespace SixLabors.ImageSharp.Formats.Png
                         finally
                         {
                             // Data is rented in ReadChunkData()
-                            if (currentChunk.Data != null)
+                            if (chunk.Data != null)
                             {
-                                currentChunk.Data.Dispose();
+                                chunk.Data.Dispose();
-                                currentChunk.Data = null;
+                                chunk.Data = null;
                             }
                         }
                     }
@@ -297,25 +296,24 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.currentStream.Skip(8);
             try
             {
-                PngChunk currentChunk;
+                while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
-                while (!this.isEndChunkReached && (currentChunk = this.ReadChunk()) != null)
                 {
                     try
                     {
-                        switch (currentChunk.Type)
+                        switch (chunk.Type)
                         {
                             case PngChunkTypes.Header:
-                                this.ReadHeaderChunk(currentChunk.Data.Array);
+                                this.ReadHeaderChunk(chunk.Data.Array);
                                 this.ValidateHeader();
                                 break;
                             case PngChunkTypes.Physical:
-                                this.ReadPhysicalChunk(metadata, currentChunk.Data.Array);
+                                this.ReadPhysicalChunk(metadata, chunk.Data.Array);
                                 break;
                             case PngChunkTypes.Data:
-                                this.SkipChunkDataAndCrc(currentChunk);
+                                this.SkipChunkDataAndCrc(chunk);
                                 break;
                             case PngChunkTypes.Text:
-                                this.ReadTextChunk(metadata, currentChunk.Data.Array, currentChunk.Length);
+                                this.ReadTextChunk(metadata, chunk.Data.Array, chunk.Length);
                                 break;
                             case PngChunkTypes.End:
                                 this.isEndChunkReached = true;
@@ -325,9 +323,9 @@ namespace SixLabors.ImageSharp.Formats.Png
                     finally
                     {
                         // Data is rented in ReadChunkData()
-                        if (currentChunk.Data != null)
+                        if (chunk.Data != null)
                         {
-                            ArrayPool<byte>.Shared.Return(currentChunk.Data.Array);
+                            ArrayPool<byte>.Shared.Return(chunk.Data.Array);
                         }
                     }
                 }
@@ -338,7 +336,7 @@ namespace SixLabors.ImageSharp.Formats.Png
                 this.previousScanline?.Dispose();
             }
 
-            if (this.header == null)
+            if (this.header.Width == 0 && this.header.Height == 0)
             {
                 throw new ImageFormatException("PNG Image does not contain a header chunk");
             }
@@ -1159,16 +1157,14 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <param name="data">The <see cref="T:ReadOnlySpan{byte}"/> containing data.</param>
         private void ReadHeaderChunk(ReadOnlySpan<byte> data)
         {
-            this.header = new PngHeader
+            this.header = new PngHeader(
-            {
+                width: BinaryPrimitives.ReadInt32BigEndian(data.Slice(0, 4)),
-                Width = BinaryPrimitives.ReadInt32BigEndian(data.Slice(0, 4)),
+                height: BinaryPrimitives.ReadInt32BigEndian(data.Slice(4, 4)),
-                Height = BinaryPrimitives.ReadInt32BigEndian(data.Slice(4, 4)),
+                bitDepth: data[8],
-                BitDepth = data[8],
+                colorType: (PngColorType)data[9],
-                ColorType = (PngColorType)data[9],
+                compressionMethod: data[10],
-                CompressionMethod = data[10],
+                filterMethod: data[11],
-                FilterMethod = data[11],
+                interlaceMethod: (PngInterlaceMode)data[12]);
-                InterlaceMethod = (PngInterlaceMode)data[12]
-            };
         }
 
         /// <summary>
@@ -1208,36 +1204,40 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <returns>
         /// The <see cref="PngChunk"/>.
         /// </returns>
-        private PngChunk ReadChunk()
+        private bool TryReadChunk(out PngChunk chunk)
         {
-            var chunk = new PngChunk();
+            int length = this.ReadChunkLength();
-            this.ReadChunkLength(chunk);
 
-            if (chunk.Length == -1)
+            if (length == -1)
             {
+                chunk = default;
+
                 // IEND
-                return null;
+                return false;
             }
 
+            chunk = new PngChunk(length);
+
             if (chunk.Length < 0 || chunk.Length > this.currentStream.Length - this.currentStream.Position)
             {
                 // Not a valid chunk so we skip back all but one of the four bytes we have just read.
                 // That lets us read one byte at a time until we reach a known chunk.
                 this.currentStream.Position -= 3;
-                return chunk;
+
+                return true;
             }
 
             this.ReadChunkType(chunk);
 
             if (chunk.Type == PngChunkTypes.Data)
             {
-                return chunk;
+                return true;
             }
 
             this.ReadChunkData(chunk);
             this.ReadChunkCrc(chunk);
 
-            return chunk;
+            return true;
         }
 
         /// <summary>
@@ -1314,21 +1314,19 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <summary>
         /// Calculates the length of the given chunk.
         /// </summary>
-        /// <param name="chunk">The chunk.</param>
         /// <exception cref="ImageFormatException">
         /// Thrown if the input stream is not valid.
         /// </exception>
-        private void ReadChunkLength(PngChunk chunk)
+        private int ReadChunkLength()
         {
             int numBytes = this.currentStream.Read(this.chunkLengthBuffer, 0, 4);
 
             if (numBytes < 4)
             {
-                chunk.Length = -1;
+                return -1;
-                return;
             }
 
-            chunk.Length = BinaryPrimitives.ReadInt32BigEndian(this.chunkLengthBuffer);
+            return BinaryPrimitives.ReadInt32BigEndian(this.chunkLengthBuffer);
         }
 
         /// <summary>

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -212,16 +212,14 @@ namespace SixLabors.ImageSharp.Formats.Png
 
             this.bytesPerPixel = this.CalculateBytesPerPixel();
 
-            var header = new PngHeader
+            var header = new PngHeader(
-            {
+                width: image.Width,
-                Width = image.Width,
+                height: image.Height,
-                Height = image.Height,
+                colorType: this.pngColorType,
-                ColorType = this.pngColorType,
+                bitDepth: this.bitDepth,
-                BitDepth = this.bitDepth,
+                filterMethod: 0, // None
-                FilterMethod = 0, // None
+                compressionMethod: 0,
-                CompressionMethod = 0,
+                interlaceMethod: 0);
-                InterlaceMethod = 0
-            };
 
             this.WriteHeaderChunk(stream, header);
 
@@ -415,7 +413,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// </summary>
         /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
         /// <param name="header">The <see cref="PngHeader"/>.</param>
-        private void WriteHeaderChunk(Stream stream, PngHeader header)
+        private void WriteHeaderChunk(Stream stream, in PngHeader header)
         {
             BinaryPrimitives.WriteInt32BigEndian(new Span<byte>(this.chunkDataBuffer, 0, 4), header.Width);
             BinaryPrimitives.WriteInt32BigEndian(new Span<byte>(this.chunkDataBuffer, 4, 4), header.Height);
@@ -436,7 +434,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
         /// <param name="header">The <see cref="PngHeader"/>.</param>
         /// <param name="quantized">The quantized frame.</param>
-        private void WritePaletteChunk<TPixel>(Stream stream, PngHeader header, QuantizedFrame<TPixel> quantized)
+        private void WritePaletteChunk<TPixel>(Stream stream, in PngHeader header, QuantizedFrame<TPixel> quantized)
             where TPixel : struct, IPixel<TPixel>
         {
             // Grab the palette and write it to the stream.

src/ImageSharp/Formats/Png/PngHeader.cs

@@ -6,55 +6,73 @@ namespace SixLabors.ImageSharp.Formats.Png
     /// <summary>
     /// Represents the png header chunk.
     /// </summary>
-    internal sealed class PngHeader
+    internal readonly struct PngHeader
     {
+        public PngHeader(
+            int width,
+            int height,
+            byte bitDepth,
+            PngColorType colorType,
+            byte compressionMethod,
+            byte filterMethod,
+            PngInterlaceMode interlaceMethod)
+        {
+            this.Width = width;
+            this.Height = height;
+            this.BitDepth = bitDepth;
+            this.ColorType = colorType;
+            this.CompressionMethod = compressionMethod;
+            this.FilterMethod = filterMethod;
+            this.InterlaceMethod = interlaceMethod;
+        }
+
         /// <summary>
-        /// Gets or sets the dimension in x-direction of the image in pixels.
+        /// Gets the dimension in x-direction of the image in pixels.
         /// </summary>
-        public int Width { get; set; }
+        public int Width { get; }
 
         /// <summary>
-        /// Gets or sets the dimension in y-direction of the image in pixels.
+        /// Gets the dimension in y-direction of the image in pixels.
         /// </summary>
-        public int Height { get; set; }
+        public int Height { get; }
 
         /// <summary>
-        /// Gets or sets the bit depth.
+        /// Gets the bit depth.
         /// Bit depth is a single-byte integer giving the number of bits per sample
         /// or per palette index (not per pixel). Valid values are 1, 2, 4, 8, and 16,
         /// although not all values are allowed for all color types.
         /// </summary>
-        public byte BitDepth { get; set; }
+        public byte BitDepth { get; }
 
         /// <summary>
-        /// Gets or sets the color type.
+        /// Gets the color type.
         /// Color type is a integer that describes the interpretation of the
         /// image data. Color type codes represent sums of the following values:
         /// 1 (palette used), 2 (color used), and 4 (alpha channel used).
         /// </summary>
-        public PngColorType ColorType { get; set; }
+        public PngColorType ColorType { get; }
 
         /// <summary>
-        /// Gets or sets the compression method.
+        /// Gets the compression method.
         /// Indicates the method used to compress the image data. At present,
         /// only compression method 0 (deflate/inflate compression with a sliding
         /// window of at most 32768 bytes) is defined.
         /// </summary>
-        public byte CompressionMethod { get; set; }
+        public byte CompressionMethod { get; }
 
         /// <summary>
-        /// Gets or sets the preprocessing method.
+        /// Gets the preprocessing method.
         /// Indicates the preprocessing method applied to the image
         /// data before compression. At present, only filter method 0
         /// (adaptive filtering with five basic filter types) is defined.
         /// </summary>
-        public byte FilterMethod { get; set; }
+        public byte FilterMethod { get; }
 
         /// <summary>
-        /// Gets or sets the  transmission order.
+        /// Gets the transmission order.
         /// Indicates the transmission order of the image data.
         /// Two values are currently defined: 0 (no interlace) or 1 (Adam7 interlace).
         /// </summary>
-        public PngInterlaceMode InterlaceMethod { get; set; }
+        public PngInterlaceMode InterlaceMethod { get; }
     }
 }

src/ImageSharp/IImageFrameCollection.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using SixLabors.ImageSharp.PixelFormats;

src/ImageSharp/Image.FromStream.cs

@@ -183,15 +183,15 @@ namespace SixLabors.ImageSharp
                 return data.img;
             }
 
-            var stringBuilder = new StringBuilder();
+            var sb = new StringBuilder();
-            stringBuilder.AppendLine("Image cannot be loaded. Available decoders:");
+            sb.AppendLine("Image cannot be loaded. Available decoders:");
 
             foreach (KeyValuePair<IImageFormat, IImageDecoder> val in config.ImageFormatsManager.ImageDecoders)
             {
-                stringBuilder.AppendLine($" - {val.Key.Name} : {val.Value.GetType().Name}");
+                sb.AppendLine($" - {val.Key.Name} : {val.Value.GetType().Name}");
             }
 
-            throw new NotSupportedException(stringBuilder.ToString());
+            throw new NotSupportedException(sb.ToString());
         }
 
         private static T WithSeekableStream<T>(Configuration config, Stream stream, Func<Stream, T> action)

src/ImageSharp/ImageExtensions.cs

@@ -35,28 +35,28 @@ namespace SixLabors.ImageSharp
             IImageFormat format = source.GetConfiguration().ImageFormatsManager.FindFormatByFileExtension(ext);
             if (format == null)
             {
-                var stringBuilder = new StringBuilder();
+                var sb = new StringBuilder();
-                stringBuilder.AppendLine($"Can't find a format that is associated with the file extention '{ext}'. Registered formats with there extensions include:");
+                sb.AppendLine($"Can't find a format that is associated with the file extention '{ext}'. Registered formats with there extensions include:");
                 foreach (IImageFormat fmt in source.GetConfiguration().ImageFormats)
                 {
-                    stringBuilder.AppendLine($" - {fmt.Name} : {string.Join(", ", fmt.FileExtensions)}");
+                    sb.AppendLine($" - {fmt.Name} : {string.Join(", ", fmt.FileExtensions)}");
                 }
 
-                throw new NotSupportedException(stringBuilder.ToString());
+                throw new NotSupportedException(sb.ToString());
             }
 
             IImageEncoder encoder = source.GetConfiguration().ImageFormatsManager.FindEncoder(format);
 
             if (encoder == null)
             {
-                var stringBuilder = new StringBuilder();
+                var sb = new StringBuilder();
-                stringBuilder.AppendLine($"Can't find encoder for file extention '{ext}' using image format '{format.Name}'. Registered encoders include:");
+                sb.AppendLine($"Can't find encoder for file extention '{ext}' using image format '{format.Name}'. Registered encoders include:");
                 foreach (KeyValuePair<IImageFormat, IImageEncoder> enc in source.GetConfiguration().ImageFormatsManager.ImageEncoders)
                 {
-                    stringBuilder.AppendLine($" - {enc.Key} : {enc.Value.GetType().Name}");
+                    sb.AppendLine($" - {enc.Key} : {enc.Value.GetType().Name}");
                 }
 
-                throw new NotSupportedException(stringBuilder.ToString());
+                throw new NotSupportedException(sb.ToString());
             }
 
             source.Save(filePath, encoder);
@@ -97,15 +97,15 @@ namespace SixLabors.ImageSharp
 
             if (encoder == null)
             {
-                var stringBuilder = new StringBuilder();
+                var sb = new StringBuilder();
-                stringBuilder.AppendLine("Can't find encoder for provided mime type. Available encoded:");
+                sb.AppendLine("Can't find encoder for provided mime type. Available encoded:");
 
                 foreach (KeyValuePair<IImageFormat, IImageEncoder> val in source.GetConfiguration().ImageFormatsManager.ImageEncoders)
                 {
-                    stringBuilder.AppendLine($" - {val.Key.Name} : {val.Value.GetType().Name}");
+                    sb.AppendLine($" - {val.Key.Name} : {val.Value.GetType().Name}");
                 }
 
-                throw new NotSupportedException(stringBuilder.ToString());
+                throw new NotSupportedException(sb.ToString());
             }
 
             source.Save(stream, encoder);

src/ImageSharp/Memory/SpanHelper.cs

@@ -11,20 +11,6 @@ namespace SixLabors.ImageSharp.Memory
     /// </summary>
     internal static class SpanHelper
     {
-        /// <summary>
-        /// Copy 'count' number of elements of the same type from 'source' to 'dest'
-        /// </summary>
-        /// <typeparam name="T">The element type.</typeparam>
-        /// <param name="source">The <see cref="Span{T}"/> to copy elements from.</param>
-        /// <param name="destination">The destination <see cref="Span{T}"/>.</param>
-        /// <param name="count">The number of elements to copy</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static unsafe void Copy<T>(ReadOnlySpan<T> source, Span<T> destination, int count)
-            where T : struct
-        {
-            source.Slice(0, count).CopyTo(destination);
-        }
-
         /// <summary>
         /// Copy all elements of 'source' into 'destination'.
         /// </summary>
@@ -35,7 +21,7 @@ namespace SixLabors.ImageSharp.Memory
         public static void Copy<T>(ReadOnlySpan<T> source, Span<T> destination)
             where T : struct
         {
-            Copy(source, destination, Math.Min(source.Length, destination.Length));
+            source.Slice(0, Math.Min(source.Length, destination.Length)).CopyTo(destination);
         }
 
         /// <summary>

src/ImageSharp/MetaData/ImageProperty.cs

@@ -10,10 +10,10 @@ namespace SixLabors.ImageSharp.MetaData
     /// the copyright information, the date, where the image was created
     /// or some other information.
     /// </summary>
-    public class ImageProperty : IEquatable<ImageProperty>
+    public readonly struct ImageProperty : IEquatable<ImageProperty>
     {
         /// <summary>
-        /// Initializes a new instance of the <see cref="ImageProperty"/> class.
+        /// Initializes a new instance of the <see cref="ImageProperty"/> struct.
         /// </summary>
         /// <param name="name">The name of the property.</param>
         /// <param name="value">The value of the property.</param>
@@ -26,7 +26,7 @@ namespace SixLabors.ImageSharp.MetaData
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="ImageProperty"/> class
+        /// Initializes a new instance of the <see cref="ImageProperty"/> struct
         /// by making a copy from another property.
         /// </summary>
         /// <param name="other">
@@ -71,11 +71,6 @@ namespace SixLabors.ImageSharp.MetaData
         /// </returns>
         public static bool operator ==(ImageProperty left, ImageProperty right)
         {
-            if (ReferenceEquals(left, right))
-            {
-                return true;
-            }
-
             return left.Equals(right);
         }
 
@@ -110,9 +105,7 @@ namespace SixLabors.ImageSharp.MetaData
         /// </returns>
         public override bool Equals(object obj)
         {
-            ImageProperty other = obj as ImageProperty;
+            return obj is ImageProperty other && this.Equals(other);
-
-            return this.Equals(other);
         }
 
         /// <summary>
@@ -155,16 +148,6 @@ namespace SixLabors.ImageSharp.MetaData
         /// <param name="other">An object to compare with this object.</param>
         public bool Equals(ImageProperty other)
         {
-            if (ReferenceEquals(other, null))
-            {
-                return false;
-            }
-
-            if (ReferenceEquals(this, other))
-            {
-                return true;
-            }
-
             return this.Name.Equals(other.Name) && Equals(this.Value, other.Value);
         }
     }

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

@@ -11,66 +11,66 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <summary>
         /// Unknown
         /// </summary>
-        Unknown,
+        Unknown = 0,
 
         /// <summary>
-        /// Byte
+        /// An 8-bit unsigned integer.
         /// </summary>
-        Byte,
+        Byte = 1,
 
         /// <summary>
-        /// Ascii
+        /// An 8-bit byte containing one 7-bit ASCII code. The final byte is terminated with NULL.
         /// </summary>
-        Ascii,
+        Ascii = 2,
 
         /// <summary>
-        /// Short
+        /// A 16-bit (2-byte) unsigned integer.
         /// </summary>
-        Short,
+        Short = 3,
 
         /// <summary>
-        /// Long
+        /// A 32-bit (4-byte) unsigned integer.
         /// </summary>
-        Long,
+        Long = 4,
 
         /// <summary>
-        /// Rational
+        /// Two LONGs. The first LONG is the numerator and the second LONG expresses the denominator.
         /// </summary>
-        Rational,
+        Rational = 5,
 
         /// <summary>
-        /// SignedByte
+        /// An 8-bit signed integer.
         /// </summary>
-        SignedByte,
+        SignedByte = 6,
 
         /// <summary>
-        /// Undefined
+        /// An 8-bit byte that can take any value depending on the field definition.
         /// </summary>
-        Undefined,
+        Undefined = 7,
 
         /// <summary>
-        /// SignedShort
+        /// A 16-bit (2-byte) signed integer.
         /// </summary>
-        SignedShort,
+        SignedShort = 8,
 
         /// <summary>
-        /// SignedLong
+        /// A 32-bit (4-byte) signed integer (2's complement notation).
         /// </summary>
-        SignedLong,
+        SignedLong = 9,
 
         /// <summary>
-        /// SignedRational
+        /// Two SLONGs. The first SLONG is the numerator and the second SLONG is the denominator.
         /// </summary>
-        SignedRational,
+        SignedRational = 10,
 
         /// <summary>
-        /// SingleFloat
+        /// A 32-bit floating point value.
         /// </summary>
-        SingleFloat,
+        SingleFloat = 11,
 
         /// <summary>
-        /// DoubleFloat
+        /// A 64-bit floating point value.
         /// </summary>
-        DoubleFloat
+        DoubleFloat = 12
     }
 }

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

@@ -23,12 +23,12 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <summary>
         /// The collection of EXIF values
         /// </summary>
-        private Collection<ExifValue> values;
+        private List<ExifValue> values;
 
         /// <summary>
         /// The list of invalid EXIF tags
         /// </summary>
-        private List<ExifTag> invalidTags;
+        private IReadOnlyList<ExifTag> invalidTags;
 
         /// <summary>
         /// The thumbnail offset position in the byte stream
@@ -75,8 +75,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             this.invalidTags = new List<ExifTag>(other.invalidTags);
             if (other.values != null)
             {
-                this.values = new Collection<ExifValue>();
+                this.values = new List<ExifValue>(other.Values.Count);
-                foreach (ExifValue value in other.values)
+
+                foreach (ExifValue value in other.Values)
                 {
                     this.values.Add(new ExifValue(value));
                 }
@@ -92,21 +93,17 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <summary>
         /// Gets or sets which parts will be written when the profile is added to an image.
         /// </summary>
-        public ExifParts Parts
+        public ExifParts Parts { get; set; }
-        {
-            get;
-            set;
-        }
 
         /// <summary>
         /// Gets the tags that where found but contained an invalid value.
         /// </summary>
-        public IEnumerable<ExifTag> InvalidTags => this.invalidTags;
+        public IReadOnlyList<ExifTag> InvalidTags => this.invalidTags;
 
         /// <summary>
         /// Gets the values of this EXIF profile.
         /// </summary>
-        public IEnumerable<ExifValue> Values
+        public IReadOnlyList<ExifValue> Values
         {
             get
             {
@@ -163,6 +160,31 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return null;
         }
 
+        /// <summary>
+        /// Conditionally returns the value of the tag if it exists.
+        /// </summary>
+        /// <param name="tag">The tag of the EXIF value.</param>
+        /// <param name="value">The value of the tag, if found.</param>
+        /// <returns>
+        /// The <see cref="bool"/>.
+        /// </returns>
+        public bool TryGetValue(ExifTag tag, out ExifValue value)
+        {
+            foreach (ExifValue exifValue in this.Values)
+            {
+                if (exifValue.Tag == tag)
+                {
+                    value = exifValue;
+
+                    return true;
+                }
+            }
+
+            value = default;
+
+            return false;
+        }
+
         /// <summary>
         /// Removes the value with the specified tag.
         /// </summary>
@@ -193,16 +215,18 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <param name="value">The value.</param>
         public void SetValue(ExifTag tag, object value)
         {
-            foreach (ExifValue exifValue in this.Values)
+            for (int i = 0; i < this.Values.Count; i++)
             {
-                if (exifValue.Tag == tag)
+                if (this.values[i].Tag == tag)
                 {
-                    exifValue.Value = value;
+                    this.values[i] = this.values[i].WithValue(value);
+
                     return;
                 }
             }
 
             var newExifValue = ExifValue.Create(tag, value);
+
             this.values.Add(newExifValue);
         }
 
@@ -262,12 +286,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
             if (this.data == null)
             {
-                this.values = new Collection<ExifValue>();
+                this.values = new List<ExifValue>();
                 return;
             }
 
-            var reader = new ExifReader();
+            var reader = new ExifReader(this.data);
-            this.values = reader.Read(this.data);
+
+            this.values = reader.ReadValues();
+
             this.invalidTags = new List<ExifTag>(reader.InvalidTags);
             this.thumbnailOffset = (int)reader.ThumbnailOffset;
             this.thumbnailLength = (int)reader.ThumbnailLength;

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

@@ -2,10 +2,13 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Buffers.Binary;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
+using System.Runtime.InteropServices;
 using System.Text;
+using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Primitives;
 
 namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
@@ -15,38 +18,37 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
     /// </summary>
     internal sealed class ExifReader
     {
-        private readonly Collection<ExifTag> invalidTags = new Collection<ExifTag>();
+        private readonly List<ExifTag> invalidTags = new List<ExifTag>();
-        private byte[] exifData;
+        private readonly byte[] exifData;
-        private uint currentIndex;
+        private int position;
-        private bool isLittleEndian;
+        private Endianness endianness = Endianness.BigEndian;
         private uint exifOffset;
         private uint gpsOffset;
-        private uint startIndex;
+        private int startIndex;
 
-        private delegate TDataType ConverterMethod<TDataType>(byte[] data);
+        public ExifReader(byte[] exifData)
+        {
+            DebugGuard.NotNull(exifData, nameof(exifData));
+
+            this.exifData = exifData;
+        }
+
+        private delegate TDataType ConverterMethod<TDataType>(ReadOnlySpan<byte> data);
 
         /// <summary>
         /// Gets the invalid tags.
         /// </summary>
-        public IEnumerable<ExifTag> InvalidTags => this.invalidTags;
+        public IReadOnlyList<ExifTag> InvalidTags => this.invalidTags;
 
         /// <summary>
         /// Gets the thumbnail length in the byte stream
         /// </summary>
-        public uint ThumbnailLength
+        public uint ThumbnailLength { get; private set; }
-        {
-            get;
-            private set;
-        }
 
         /// <summary>
         /// Gets the thumbnail offset position in the byte stream
         /// </summary>
-        public uint ThumbnailOffset
+        public uint ThumbnailOffset { get; private set; }
-        {
-            get;
-            private set;
-        }
 
         /// <summary>
         /// Gets the remaining length.
@@ -55,81 +57,78 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         {
             get
             {
-                if (this.currentIndex >= this.exifData.Length)
+                if (this.position >= this.exifData.Length)
                 {
                     return 0;
                 }
 
-                return this.exifData.Length - (int)this.currentIndex;
+                return this.exifData.Length - this.position;
             }
         }
 
         /// <summary>
         /// Reads and returns the collection of EXIF values.
         /// </summary>
-        /// <param name="data">The data.</param>
         /// <returns>
         /// The <see cref="Collection{ExifValue}"/>.
         /// </returns>
-        public Collection<ExifValue> Read(byte[] data)
+        public List<ExifValue> ReadValues()
         {
-            DebugGuard.NotNull(data, nameof(data));
+            var values = new List<ExifValue>();
-
-            var result = new Collection<ExifValue>();
 
-            this.exifData = data;
+            if (this.ReadString(4) == "Exif")
-
-            if (this.GetString(4) == "Exif")
             {
-                if (this.GetShort() != 0)
+                if (this.ReadUInt16() != 0)
                 {
-                    return result;
+                    return values;
                 }
 
                 this.startIndex = 6;
             }
             else
             {
-                this.currentIndex = 0;
+                this.position = 0;
             }
 
-            this.isLittleEndian = this.GetString(2) == "II";
+            if (this.ReadString(2) == "II")
+            {
+                this.endianness = Endianness.LittleEndian;
+            }
 
-            if (this.GetShort() != 0x002A)
+            if (this.ReadUInt16() != 0x002A)
             {
-                return result;
+                return values;
             }
 
-            uint ifdOffset = this.GetLong();
+            uint ifdOffset = this.ReadUInt32();
-            this.AddValues(result, ifdOffset);
+            this.AddValues(values, (int)ifdOffset);
 
-            uint thumbnailOffset = this.GetLong();
+            uint thumbnailOffset = this.ReadUInt32();
-            this.GetThumbnail(thumbnailOffset);
+            this.GetThumbnail((int)thumbnailOffset);
 
             if (this.exifOffset != 0)
             {
-                this.AddValues(result, this.exifOffset);
+                this.AddValues(values, (int)this.exifOffset);
             }
 
             if (this.gpsOffset != 0)
             {
-                this.AddValues(result, this.gpsOffset);
+                this.AddValues(values, (int)this.gpsOffset);
             }
 
-            return result;
+            return values;
         }
 
-        private static TDataType[] ToArray<TDataType>(ExifDataType dataType, byte[] data, ConverterMethod<TDataType> converter)
+        private static TDataType[] ToArray<TDataType>(ExifDataType dataType, ReadOnlySpan<byte> data, ConverterMethod<TDataType> converter)
         {
             int dataTypeSize = (int)ExifValue.GetSize(dataType);
             int length = data.Length / dataTypeSize;
 
-            TDataType[] result = new TDataType[length];
+            var result = new TDataType[length];
-            byte[] buffer = new byte[dataTypeSize];
 
             for (int i = 0; i < length; i++)
             {
-                Array.Copy(data, i * dataTypeSize, buffer, 0, dataTypeSize);
+                ReadOnlySpan<byte> buffer = data.Slice(i * dataTypeSize, dataTypeSize);
 
                 result.SetValue(converter(buffer), i);
             }
@@ -137,14 +136,23 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return result;
         }
 
-        private static byte ToByte(byte[] data)
+        private byte ConvertToByte(ReadOnlySpan<byte> buffer) => buffer[0];
-        {
-            return data[0];
-        }
 
-        private static string ToString(byte[] data)
+        private unsafe string ConvertToString(ReadOnlySpan<byte> buffer)
         {
-            string result = Encoding.UTF8.GetString(data, 0, data.Length);
+#if NETSTANDARD1_1
+            byte[] bytes = buffer.ToArray();
+
+            string result = Encoding.UTF8.GetString(bytes, 0, buffer.Length);
+
+#else
+            string result;
+
+            fixed (byte* pointer = &MemoryMarshal.GetReference(buffer))
+            {
+                result = Encoding.UTF8.GetString(pointer, buffer.Length);
+            }
+#endif
             int nullCharIndex = result.IndexOf('\0');
             if (nullCharIndex != -1)
             {
@@ -159,15 +167,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// </summary>
         /// <param name="values">The values.</param>
         /// <param name="index">The index.</param>
-        private void AddValues(Collection<ExifValue> values, uint index)
+        private void AddValues(List<ExifValue> values, int index)
         {
-            this.currentIndex = this.startIndex + index;
+            this.position = this.startIndex + index;
-            ushort count = this.GetShort();
+            int count = this.ReadUInt16();
 
-            for (ushort i = 0; i < count; i++)
+            for (int i = 0; i < count; i++)
             {
-                ExifValue value = this.CreateValue();
+                if (!this.TryReadValue(out ExifValue value))
-                if (value == null)
                 {
                     continue;
                 }
@@ -208,9 +215,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             }
         }
 
-        private object ConvertValue(ExifDataType dataType, byte[] data, uint numberOfComponents)
+        private object ConvertValue(ExifDataType dataType, ReadOnlySpan<byte> buffer, uint numberOfComponents)
         {
-            if (data == null || data.Length == 0)
+            if (buffer == null || buffer.Length == 0)
             {
                 return null;
             }
@@ -220,106 +227,116 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifDataType.Unknown:
                     return null;
                 case ExifDataType.Ascii:
-                    return ToString(data);
+                    return this.ConvertToString(buffer);
                 case ExifDataType.Byte:
                     if (numberOfComponents == 1)
                     {
-                        return ToByte(data);
+                        return this.ConvertToByte(buffer);
                     }
 
-                    return data;
+                    return buffer.ToArray();
                 case ExifDataType.DoubleFloat:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToDouble(data);
+                        return this.ConvertToDouble(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToDouble);
+                    return ToArray(dataType, buffer, this.ConvertToDouble);
                 case ExifDataType.Long:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToLong(data);
+                        return this.ConvertToUInt32(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToLong);
+                    return ToArray(dataType, buffer, this.ConvertToUInt32);
                 case ExifDataType.Rational:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToRational(data);
+                        return this.ToRational(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToRational);
+                    return ToArray(dataType, buffer, this.ToRational);
                 case ExifDataType.Short:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToShort(data);
+                        return this.ConvertToShort(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToShort);
+                    return ToArray(dataType, buffer, this.ConvertToShort);
                 case ExifDataType.SignedByte:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToSignedByte(data);
+                        return this.ConvertToSignedByte(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToSignedByte);
+                    return ToArray(dataType, buffer, this.ConvertToSignedByte);
                 case ExifDataType.SignedLong:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToSignedLong(data);
+                        return this.ConvertToInt32(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToSignedLong);
+                    return ToArray(dataType, buffer, this.ConvertToInt32);
                 case ExifDataType.SignedRational:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToSignedRational(data);
+                        return this.ToSignedRational(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToSignedRational);
+                    return ToArray(dataType, buffer, this.ToSignedRational);
                 case ExifDataType.SignedShort:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToSignedShort(data);
+                        return this.ConvertToSignedShort(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToSignedShort);
+                    return ToArray(dataType, buffer, this.ConvertToSignedShort);
                 case ExifDataType.SingleFloat:
                     if (numberOfComponents == 1)
                     {
-                        return this.ToSingle(data);
+                        return this.ConvertToSingle(buffer);
                     }
 
-                    return ToArray(dataType, data, this.ToSingle);
+                    return ToArray(dataType, buffer, this.ConvertToSingle);
                 case ExifDataType.Undefined:
                     if (numberOfComponents == 1)
                     {
-                        return ToByte(data);
+                        return this.ConvertToByte(buffer);
                     }
 
-                    return data;
+                    return buffer.ToArray();
                 default:
                     throw new NotSupportedException();
             }
         }
 
-        private ExifValue CreateValue()
+        private bool TryReadValue(out ExifValue exifValue)
         {
+            // 2   | 2    | 4     | 4
+            // tag | type | count | value offset
             if (this.RemainingLength < 12)
             {
-                return null;
+                exifValue = default;
+
+                return false;
             }
 
-            ExifTag tag = this.ToEnum(this.GetShort(), ExifTag.Unknown);
+            ExifTag tag = this.ToEnum(this.ReadUInt16(), ExifTag.Unknown);
-            ExifDataType dataType = this.ToEnum(this.GetShort(), ExifDataType.Unknown);
+            uint type = this.ReadUInt16();
-            object value;
 
-            if (dataType == ExifDataType.Unknown)
+            // Ensure that the data type is valid
+            if (type == 0 || type > 12)
             {
-                return new ExifValue(tag, dataType, null, false);
+                exifValue = new ExifValue(tag, ExifDataType.Unknown, null, false);
+
+                return true;
             }
 
-            uint numberOfComponents = this.GetLong();
+            var dataType = (ExifDataType)type;
+
+            object value;
+
+            uint numberOfComponents = this.ReadUInt32();
 
             // Issue #132: ExifDataType == Undefined is treated like a byte array.
             // If numberOfComponents == 0 this value can only be handled as an inline value and must fallback to 4 (bytes)
@@ -329,29 +346,50 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             }
 
             uint size = numberOfComponents * ExifValue.GetSize(dataType);
-            byte[] data = this.GetBytes(4);
+
+            this.TryReadSpan(4, out ReadOnlySpan<byte> offsetBuffer);
 
             if (size > 4)
             {
-                uint oldIndex = this.currentIndex;
+                int oldIndex = this.position;
-                this.currentIndex = this.ToLong(data) + this.startIndex;
+
+                uint newIndex = this.ConvertToUInt32(offsetBuffer) + (uint)this.startIndex;
+
+                // Ensure that the new index does not overrun the data
+                if (newIndex > int.MaxValue)
+                {
+                    this.invalidTags.Add(tag);
+
+                    exifValue = default;
+
+                    return false;
+                }
+
+                this.position = (int)newIndex;
+
                 if (this.RemainingLength < size)
                 {
                     this.invalidTags.Add(tag);
-                    this.currentIndex = oldIndex;
+                    this.position = oldIndex;
-                    return null;
+
+                    exifValue = default;
+
+                    return false;
                 }
 
-                value = this.ConvertValue(dataType, this.GetBytes(size), numberOfComponents);
+                this.TryReadSpan((int)size, out ReadOnlySpan<byte> dataBuffer);
-                this.currentIndex = oldIndex;
+
+                value = this.ConvertValue(dataType, dataBuffer, numberOfComponents);
+                this.position = oldIndex;
             }
             else
             {
-                value = this.ConvertValue(dataType, data, numberOfComponents);
+                value = this.ConvertValue(dataType, offsetBuffer, numberOfComponents);
             }
 
-            bool isArray = value != null && numberOfComponents > 1;
+            exifValue = new ExifValue(tag, dataType, value, isArray: value != null && numberOfComponents > 1);
-            return new ExifValue(tag, dataType, value, isArray);
+
+            return true;
         }
 
         private TEnum ToEnum<TEnum>(int value, TEnum defaultValue)
@@ -366,51 +404,57 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return defaultValue;
         }
 
-        private byte[] GetBytes(uint length)
+        private bool TryReadSpan(int length, out ReadOnlySpan<byte> span)
         {
-            if (this.currentIndex + length > (uint)this.exifData.Length)
+            if (this.RemainingLength < length)
             {
-                return null;
+                span = default;
+
+                return false;
             }
 
-            byte[] data = new byte[length];
+            span = new ReadOnlySpan<byte>(this.exifData, this.position, length);
-            Array.Copy(this.exifData, (int)this.currentIndex, data, 0, (int)length);
-            this.currentIndex += length;
 
-            return data;
+            this.position += length;
+
+            return true;
         }
 
-        private uint GetLong()
+        private uint ReadUInt32()
         {
-            return this.ToLong(this.GetBytes(4));
+            // Known as Long in Exif Specification
+            return this.TryReadSpan(4, out ReadOnlySpan<byte> span)
+                ? this.ConvertToUInt32(span)
+                : default;
         }
 
-        private ushort GetShort()
+        private ushort ReadUInt16()
         {
-            return this.ToShort(this.GetBytes(2));
+            return this.TryReadSpan(2, out ReadOnlySpan<byte> span)
+                ? this.ConvertToShort(span)
+                : default;
         }
 
-        private string GetString(uint length)
+        private string ReadString(int length)
         {
-            byte[] data = this.GetBytes(length);
+            if (this.TryReadSpan(length, out ReadOnlySpan<byte> span) && span.Length != 0)
-            if (data == null || data.Length == 0)
             {
-                return null;
+                return this.ConvertToString(span);
             }
 
-            return ToString(data);
+            return null;
         }
 
-        private void GetThumbnail(uint offset)
+        private void GetThumbnail(int offset)
         {
-            var values = new Collection<ExifValue>();
+            var values = new List<ExifValue>();
             this.AddValues(values, offset);
 
             foreach (ExifValue value in values)
             {
                 if (value.Tag == ExifTag.JPEGInterchangeFormat && (value.DataType == ExifDataType.Long))
                 {
-                    this.ThumbnailOffset = (uint)value.Value + this.startIndex;
+                    this.ThumbnailOffset = (uint)value.Value + (uint)this.startIndex;
                 }
                 else if (value.Tag == ExifTag.JPEGInterchangeFormatLength && value.DataType == ExifDataType.Long)
                 {
@@ -419,120 +463,112 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             }
         }
 
-        private double ToDouble(byte[] data)
+        private unsafe double ConvertToDouble(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 8))
+            if (buffer.Length < 8)
             {
-                return default(double);
+                return default;
             }
 
-            return BitConverter.ToDouble(data, 0);
+            long intValue = this.endianness == Endianness.BigEndian
+                ? BinaryPrimitives.ReadInt64BigEndian(buffer)
+                : BinaryPrimitives.ReadInt64LittleEndian(buffer);
+
+            return *((double*)&intValue);
         }
 
-        private uint ToLong(byte[] data)
+        private uint ConvertToUInt32(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 4))
+            // Known as Long in Exif Specification
+            if (buffer.Length < 4)
             {
-                return default(uint);
+                return default;
             }
 
-            return BitConverter.ToUInt32(data, 0);
+            return this.endianness == Endianness.BigEndian
+                ? BinaryPrimitives.ReadUInt32BigEndian(buffer)
+                : BinaryPrimitives.ReadUInt32LittleEndian(buffer);
         }
 
-        private ushort ToShort(byte[] data)
+        private ushort ConvertToShort(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 2))
+            if (buffer.Length < 2)
             {
-                return default(ushort);
+                return default;
             }
 
-            return BitConverter.ToUInt16(data, 0);
+            return this.endianness == Endianness.BigEndian
+                ? BinaryPrimitives.ReadUInt16BigEndian(buffer)
+                : BinaryPrimitives.ReadUInt16LittleEndian(buffer);
         }
 
-        private float ToSingle(byte[] data)
+        private unsafe float ConvertToSingle(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 4))
+            if (buffer.Length < 4)
             {
-                return default(float);
+                return default;
             }
 
-            return BitConverter.ToSingle(data, 0);
+            int intValue = this.endianness == Endianness.BigEndian
+                ? BinaryPrimitives.ReadInt32BigEndian(buffer)
+                : BinaryPrimitives.ReadInt32LittleEndian(buffer);
+
+            return *((float*)&intValue);
         }
 
-        private Rational ToRational(byte[] data)
+        private Rational ToRational(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 8, 4))
+            if (buffer.Length < 8)
             {
-                return default(Rational);
+                return default;
             }
 
-            uint numerator = BitConverter.ToUInt32(data, 0);
+            uint numerator = this.ConvertToUInt32(buffer.Slice(0, 4));
-            uint denominator = BitConverter.ToUInt32(data, 4);
+            uint denominator = this.ConvertToUInt32(buffer.Slice(4, 4));
 
             return new Rational(numerator, denominator, false);
         }
 
-        private sbyte ToSignedByte(byte[] data)
+        private sbyte ConvertToSignedByte(ReadOnlySpan<byte> buffer)
         {
-            return unchecked((sbyte)data[0]);
+            return unchecked((sbyte)buffer[0]);
         }
 
-        private int ToSignedLong(byte[] data)
+        private int ConvertToInt32(ReadOnlySpan<byte> buffer) // SignedLong in Exif Specification
         {
-            if (!this.ValidateArray(data, 4))
+            if (buffer.Length < 4)
             {
-                return default(int);
+                return default;
             }
 
-            return BitConverter.ToInt32(data, 0);
+            return this.endianness == Endianness.BigEndian
+                ? BinaryPrimitives.ReadInt32BigEndian(buffer)
+                : BinaryPrimitives.ReadInt32LittleEndian(buffer);
         }
 
-        private SignedRational ToSignedRational(byte[] data)
+        private SignedRational ToSignedRational(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 8, 4))
+            if (buffer.Length < 8)
             {
-                return default(SignedRational);
+                return default;
             }
 
-            int numerator = BitConverter.ToInt32(data, 0);
+            int numerator = this.ConvertToInt32(buffer.Slice(0, 4));
-            int denominator = BitConverter.ToInt32(data, 4);
+            int denominator = this.ConvertToInt32(buffer.Slice(4, 4));
 
             return new SignedRational(numerator, denominator, false);
         }
 
-        private short ToSignedShort(byte[] data)
+        private short ConvertToSignedShort(ReadOnlySpan<byte> buffer)
         {
-            if (!this.ValidateArray(data, 2))
+            if (buffer.Length < 2)
             {
-                return default(short);
+                return default;
             }
 
-            return BitConverter.ToInt16(data, 0);
+            return this.endianness == Endianness.BigEndian
-        }
+                ? BinaryPrimitives.ReadInt16BigEndian(buffer)
-
+                : BinaryPrimitives.ReadInt16LittleEndian(buffer);
-        private bool ValidateArray(byte[] data, int size)
-        {
-            return this.ValidateArray(data, size, size);
-        }
-
-        private bool ValidateArray(byte[] data, int size, int stepSize)
-        {
-            if (data == null || data.Length < size)
-            {
-                return false;
-            }
-
-            if (this.isLittleEndian == BitConverter.IsLittleEndian)
-            {
-                return true;
-            }
-
-            for (int i = 0; i < data.Length; i += stepSize)
-            {
-                Array.Reverse(data, i, stepSize);
-            }
-
-            return true;
         }
     }
 }

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

@@ -0,0 +1,281 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using static SixLabors.ImageSharp.MetaData.Profiles.Exif.ExifTag;
+
+namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
+{
+    internal static class ExifTags
+    {
+        /// <summary>
+        /// The collection if Image File Directory tags
+        /// </summary>
+        public static readonly ExifTag[] Ifd =
+        {
+            SubfileType,
+            OldSubfileType,
+            ImageWidth,
+            ImageLength,
+            BitsPerSample,
+            Compression,
+            PhotometricInterpretation,
+            Thresholding,
+            CellWidth,
+            CellLength,
+            FillOrder,
+            DocumentName,
+            ImageDescription,
+            Make,
+            Model,
+            StripOffsets,
+            Orientation,
+            SamplesPerPixel,
+            RowsPerStrip,
+            StripByteCounts,
+            MinSampleValue,
+            MaxSampleValue,
+            XResolution,
+            YResolution,
+            PlanarConfiguration,
+            PageName,
+            XPosition,
+            YPosition,
+            FreeOffsets,
+            FreeByteCounts,
+            GrayResponseUnit,
+            GrayResponseCurve,
+            T4Options,
+            T6Options,
+            ResolutionUnit,
+            PageNumber,
+            ColorResponseUnit,
+            TransferFunction,
+            Software,
+            DateTime,
+            Artist,
+            HostComputer,
+            Predictor,
+            WhitePoint,
+            PrimaryChromaticities,
+            ColorMap,
+            HalftoneHints,
+            TileWidth,
+            TileLength,
+            TileOffsets,
+            TileByteCounts,
+            BadFaxLines,
+            CleanFaxData,
+            ConsecutiveBadFaxLines,
+            InkSet,
+            InkNames,
+            NumberOfInks,
+            DotRange,
+            TargetPrinter,
+            ExtraSamples,
+            SampleFormat,
+            SMinSampleValue,
+            SMaxSampleValue,
+            TransferRange,
+            ClipPath,
+            XClipPathUnits,
+            YClipPathUnits,
+            Indexed,
+            JPEGTables,
+            OPIProxy,
+            ProfileType,
+            FaxProfile,
+            CodingMethods,
+            VersionYear,
+            ModeNumber,
+            Decode,
+            DefaultImageColor,
+            T82ptions,
+            JPEGProc,
+            JPEGInterchangeFormat,
+            JPEGInterchangeFormatLength,
+            JPEGRestartInterval,
+            JPEGLosslessPredictors,
+            JPEGPointTransforms,
+            JPEGQTables,
+            JPEGDCTables,
+            JPEGACTables,
+            YCbCrCoefficients,
+            YCbCrSubsampling,
+            YCbCrSubsampling,
+            YCbCrPositioning,
+            ReferenceBlackWhite,
+            StripRowCounts,
+            XMP,
+            Rating,
+            RatingPercent,
+            ImageID,
+            CFARepeatPatternDim,
+            CFAPattern2,
+            BatteryLevel,
+            Copyright,
+            MDFileTag,
+            MDScalePixel,
+            MDLabName,
+            MDSampleInfo,
+            MDPrepDate,
+            MDPrepTime,
+            MDFileUnits,
+            PixelScale,
+            IntergraphPacketData,
+            IntergraphRegisters,
+            IntergraphMatrix,
+            ModelTiePoint,
+            SEMInfo,
+            ModelTransform,
+            ImageLayer,
+            FaxRecvParams,
+            FaxSubaddress,
+            FaxRecvTime,
+            ImageSourceData,
+            XPTitle,
+            XPComment,
+            XPAuthor,
+            XPKeywords,
+            XPSubject,
+            GDALMetadata,
+            GDALNoData
+        };
+
+        /// <summary>
+        /// The collection of Exif tags
+        /// </summary>
+        public static readonly ExifTag[] Exif =
+        {
+            ExposureTime,
+            FNumber,
+            ExposureProgram,
+            SpectralSensitivity,
+            ISOSpeedRatings,
+            OECF,
+            Interlace,
+            TimeZoneOffset,
+            SelfTimerMode,
+            SensitivityType,
+            StandardOutputSensitivity,
+            RecommendedExposureIndex,
+            ISOSpeed,
+            ISOSpeedLatitudeyyy,
+            ISOSpeedLatitudezzz,
+            ExifVersion,
+            DateTimeOriginal,
+            DateTimeDigitized,
+            OffsetTime,
+            OffsetTimeOriginal,
+            OffsetTimeDigitized,
+            ComponentsConfiguration,
+            CompressedBitsPerPixel,
+            ShutterSpeedValue,
+            ApertureValue,
+            BrightnessValue,
+            ExposureBiasValue,
+            MaxApertureValue,
+            SubjectDistance,
+            MeteringMode,
+            LightSource,
+            Flash,
+            FocalLength,
+            FlashEnergy2,
+            SpatialFrequencyResponse2,
+            Noise,
+            FocalPlaneXResolution2,
+            FocalPlaneYResolution2,
+            FocalPlaneResolutionUnit2,
+            ImageNumber,
+            SecurityClassification,
+            ImageHistory,
+            SubjectArea,
+            ExposureIndex2,
+            TIFFEPStandardID,
+            SensingMethod2,
+            MakerNote,
+            UserComment,
+            SubsecTime,
+            SubsecTimeOriginal,
+            SubsecTimeDigitized,
+            AmbientTemperature,
+            Humidity,
+            Pressure,
+            WaterDepth,
+            Acceleration,
+            CameraElevationAngle,
+            FlashpixVersion,
+            ColorSpace,
+            PixelXDimension,
+            PixelYDimension,
+            RelatedSoundFile,
+            FlashEnergy,
+            SpatialFrequencyResponse,
+            FocalPlaneXResolution,
+            FocalPlaneYResolution,
+            FocalPlaneResolutionUnit,
+            SubjectLocation,
+            ExposureIndex,
+            SensingMethod,
+            FileSource,
+            SceneType,
+            CFAPattern,
+            CustomRendered,
+            ExposureMode,
+            WhiteBalance,
+            DigitalZoomRatio,
+            FocalLengthIn35mmFilm,
+            SceneCaptureType,
+            GainControl,
+            Contrast,
+            Saturation,
+            Sharpness,
+            DeviceSettingDescription,
+            SubjectDistanceRange,
+            ImageUniqueID,
+            OwnerName,
+            SerialNumber,
+            LensInfo,
+            LensMake,
+            LensModel,
+            LensSerialNumber
+          };
+
+        /// <summary>
+        /// The collection of GPS tags
+        /// </summary>
+        public static readonly ExifTag[] Gps =
+        {
+            GPSVersionID,
+            GPSLatitudeRef,
+            GPSLatitude,
+            GPSLongitudeRef,
+            GPSLongitude,
+            GPSAltitudeRef,
+            GPSAltitude,
+            GPSTimestamp,
+            GPSSatellites,
+            GPSStatus,
+            GPSMeasureMode,
+            GPSDOP,
+            GPSSpeedRef,
+            GPSSpeed,
+            GPSTrackRef,
+            GPSTrack,
+            GPSImgDirectionRef,
+            GPSImgDirection,
+            GPSMapDatum,
+            GPSDestLatitudeRef,
+            GPSDestLatitude,
+            GPSDestLongitudeRef,
+            GPSDestLongitude,
+            GPSDestBearingRef,
+            GPSDestBearing,
+            GPSDestDistanceRef,
+            GPSDestDistance,
+            GPSProcessingMethod,
+            GPSAreaInformation,
+            GPSDateStamp,
+            GPSDifferential
+        };
+    }
+}

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

@@ -13,11 +13,6 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
     /// </summary>
     public sealed class ExifValue : IEquatable<ExifValue>
     {
-        /// <summary>
-        /// The exif value.
-        /// </summary>
-        private object exifValue;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="ExifValue"/> class
         /// by making a copy from another exif value.
@@ -34,30 +29,12 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
             if (!other.IsArray)
             {
-                this.exifValue = other.exifValue;
+                this.Value = other.Value;
             }
             else
             {
-                var array = (Array)other.exifValue;
+                var array = (Array)other.Value;
-                this.exifValue = array.Clone();
+                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="isArray">Whether the value is an array.</param>
-        internal ExifValue(ExifTag tag, ExifDataType dataType, bool isArray)
-        {
-            this.Tag = tag;
-            this.DataType = dataType;
-            this.IsArray = isArray;
-
-            if (dataType == ExifDataType.Ascii)
-            {
-                this.IsArray = false;
             }
         }
 
@@ -69,51 +46,32 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <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, dataType, isArray)
         {
-            this.exifValue = value;
+            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>
-        public ExifDataType DataType
+        public ExifDataType DataType { get; }
-        {
-            get;
-        }
 
         /// <summary>
         /// Gets a value indicating whether the value is an array.
         /// </summary>
-        public bool IsArray
+        public bool IsArray { get; }
-        {
-            get;
-        }
 
         /// <summary>
         /// Gets the tag of the exif value.
         /// </summary>
-        public ExifTag Tag
+        public ExifTag Tag { get; }
-        {
-            get;
-        }
 
         /// <summary>
-        /// Gets or sets the value.
+        /// Gets the value.
         /// </summary>
-        public object Value
+        public object Value { get; }
-        {
-            get
-            {
-                return this.exifValue;
-            }
-
-            set
-            {
-                this.CheckValue(value);
-                this.exifValue = value;
-            }
-        }
 
         /// <summary>
         /// Gets a value indicating whether the EXIF value has a value.
@@ -122,14 +80,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         {
             get
             {
-                if (this.exifValue == null)
+                if (this.Value == null)
                 {
                     return false;
                 }
 
                 if (this.DataType == ExifDataType.Ascii)
                 {
-                    return ((string)this.exifValue).Length > 0;
+                    return ((string)this.Value).Length > 0;
                 }
 
                 return true;
@@ -143,7 +101,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         {
             get
             {
-                if (this.exifValue == null)
+                if (this.Value == null)
                 {
                     return 4;
                 }
@@ -163,12 +121,12 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             {
                 if (this.DataType == ExifDataType.Ascii)
                 {
-                    return Encoding.UTF8.GetBytes((string)this.exifValue).Length;
+                    return Encoding.UTF8.GetBytes((string)this.Value).Length;
                 }
 
                 if (this.IsArray)
                 {
-                    return ((Array)this.exifValue).Length;
+                    return ((Array)this.Value).Length;
                 }
 
                 return 1;
@@ -217,12 +175,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(this, obj))
+            return obj is ExifValue other && this.Equals(other);
-            {
-                return true;
-            }
-
-            return this.Equals(obj as ExifValue);
         }
 
         /// <inheritdoc />
@@ -241,7 +194,19 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return
               this.Tag == other.Tag &&
               this.DataType == other.DataType &&
-              object.Equals(this.exifValue, other.exifValue);
+              object.Equals(this.Value, other.Value);
+        }
+
+        /// <summary>
+        /// Clones the current value, overwriting the value.
+        /// </summary>
+        /// <param name="value">The value to overwrite.</param>
+        /// <returns><see cref="ExifValue"/></returns>
+        public ExifValue WithValue(object value)
+        {
+            this.CheckValue(value);
+
+            return new ExifValue(this.Tag, this.DataType, value, this.IsArray);
         }
 
         /// <inheritdoc/>
@@ -253,26 +218,26 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <inheritdoc/>
         public override string ToString()
         {
-            if (this.exifValue == null)
+            if (this.Value == null)
             {
                 return null;
             }
 
             if (this.DataType == ExifDataType.Ascii)
             {
-                return (string)this.exifValue;
+                return (string)this.Value;
             }
 
             if (!this.IsArray)
             {
-                return this.ToString(this.exifValue);
+                return this.ToString(this.Value);
             }
 
             var sb = new StringBuilder();
-            foreach (object value in (Array)this.exifValue)
+            foreach (object value in (Array)this.Value)
             {
                 sb.Append(this.ToString(value));
-                sb.Append(" ");
+                sb.Append(' ');
             }
 
             return sb.ToString();
@@ -293,13 +258,6 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         {
             Guard.IsFalse(tag == ExifTag.Unknown, nameof(tag), "Invalid Tag");
 
-            ExifValue exifValue;
-            Type type = value?.GetType();
-            if (type != null && type.IsArray)
-            {
-                type = type.GetElementType();
-            }
-
             switch (tag)
             {
                 case ExifTag.ImageDescription:
@@ -355,8 +313,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.GPSDestBearingRef:
                 case ExifTag.GPSDestDistanceRef:
                 case ExifTag.GPSDateStamp:
-                    exifValue = new ExifValue(tag, ExifDataType.Ascii, true);
+                    return new ExifValue(tag, ExifDataType.Ascii, value, true);
-                    break;
 
                 case ExifTag.ClipPath:
                 case ExifTag.VersionYear:
@@ -369,13 +326,12 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.XPKeywords:
                 case ExifTag.XPSubject:
                 case ExifTag.GPSVersionID:
-                    exifValue = new ExifValue(tag, ExifDataType.Byte, true);
+                    return new ExifValue(tag, ExifDataType.Byte, value, true);
-                    break;
+
                 case ExifTag.FaxProfile:
                 case ExifTag.ModeNumber:
                 case ExifTag.GPSAltitudeRef:
-                    exifValue = new ExifValue(tag, ExifDataType.Byte, false);
+                    return new ExifValue(tag, ExifDataType.Byte, value, false);
-                    break;
 
                 case ExifTag.FreeOffsets:
                 case ExifTag.FreeByteCounts:
@@ -389,8 +345,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.StripRowCounts:
                 case ExifTag.IntergraphRegisters:
                 case ExifTag.TimeZoneOffset:
-                    exifValue = new ExifValue(tag, ExifDataType.Long, true);
+                    return new ExifValue(tag, ExifDataType.Long, value, true);
-                    break;
                 case ExifTag.SubfileType:
                 case ExifTag.SubIFDOffset:
                 case ExifTag.GPSIFDOffset:
@@ -412,8 +367,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.FaxRecvParams:
                 case ExifTag.FaxRecvTime:
                 case ExifTag.ImageNumber:
-                    exifValue = new ExifValue(tag, ExifDataType.Long, false);
+                    return new ExifValue(tag, ExifDataType.Long, value, false);
-                    break;
 
                 case ExifTag.WhitePoint:
                 case ExifTag.PrimaryChromaticities:
@@ -428,8 +382,8 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.GPSTimestamp:
                 case ExifTag.GPSDestLatitude:
                 case ExifTag.GPSDestLongitude:
-                    exifValue = new ExifValue(tag, ExifDataType.Rational, true);
+                    return new ExifValue(tag, ExifDataType.Rational, value, true);
-                    break;
+
                 case ExifTag.XPosition:
                 case ExifTag.YPosition:
                 case ExifTag.XResolution:
@@ -463,8 +417,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.GPSImgDirection:
                 case ExifTag.GPSDestBearing:
                 case ExifTag.GPSDestDistance:
-                    exifValue = new ExifValue(tag, ExifDataType.Rational, false);
+                    return new ExifValue(tag, ExifDataType.Rational, value, false);
-                    break;
 
                 case ExifTag.BitsPerSample:
                 case ExifTag.MinSampleValue:
@@ -487,8 +440,8 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.ISOSpeedRatings:
                 case ExifTag.SubjectArea:
                 case ExifTag.SubjectLocation:
-                    exifValue = new ExifValue(tag, ExifDataType.Short, true);
+                    return new ExifValue(tag, ExifDataType.Short, value, true);
-                    break;
+
                 case ExifTag.OldSubfileType:
                 case ExifTag.Compression:
                 case ExifTag.PhotometricInterpretation:
@@ -535,20 +488,18 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.Sharpness:
                 case ExifTag.SubjectDistanceRange:
                 case ExifTag.GPSDifferential:
-                    exifValue = new ExifValue(tag, ExifDataType.Short, false);
+                    return new ExifValue(tag, ExifDataType.Short, value, false);
-                    break;
 
                 case ExifTag.Decode:
-                    exifValue = new ExifValue(tag, ExifDataType.SignedRational, true);
+                    return new ExifValue(tag, ExifDataType.SignedRational, value, true);
-                    break;
+
                 case ExifTag.ShutterSpeedValue:
                 case ExifTag.BrightnessValue:
                 case ExifTag.ExposureBiasValue:
                 case ExifTag.AmbientTemperature:
                 case ExifTag.WaterDepth:
                 case ExifTag.CameraElevationAngle:
-                    exifValue = new ExifValue(tag, ExifDataType.SignedRational, false);
+                    return new ExifValue(tag, ExifDataType.SignedRational, value, false);
-                    break;
 
                 case ExifTag.JPEGTables:
                 case ExifTag.OECF:
@@ -565,18 +516,17 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.ImageSourceData:
                 case ExifTag.GPSProcessingMethod:
                 case ExifTag.GPSAreaInformation:
-                    exifValue = new ExifValue(tag, ExifDataType.Undefined, true);
+                    return new ExifValue(tag, ExifDataType.Undefined, value, true);
-                    break;
+
                 case ExifTag.FileSource:
                 case ExifTag.SceneType:
-                    exifValue = new ExifValue(tag, ExifDataType.Undefined, false);
+                    return new ExifValue(tag, ExifDataType.Undefined, value, false);
-                    break;
 
                 case ExifTag.StripOffsets:
                 case ExifTag.TileByteCounts:
                 case ExifTag.ImageLayer:
-                    exifValue = CreateNumber(tag, type, true);
+                    return CreateNumber(tag, value, true);
-                    break;
+
                 case ExifTag.ImageWidth:
                 case ExifTag.ImageLength:
                 case ExifTag.TileWidth:
@@ -585,15 +535,11 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 case ExifTag.ConsecutiveBadFaxLines:
                 case ExifTag.PixelXDimension:
                 case ExifTag.PixelYDimension:
-                    exifValue = CreateNumber(tag, type, false);
+                    return CreateNumber(tag, value, false);
-                    break;
 
                 default:
                     throw new NotSupportedException();
             }
-
-            exifValue.Value = value;
-            return exifValue;
         }
 
         /// <summary>
@@ -635,29 +581,35 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// Returns an EXIF value with a numeric type for the given tag.
         /// </summary>
         /// <param name="tag">The tag.</param>
-        /// <param name="type">The numeric type.</param>
+        /// <param name="value">The value.</param>
         /// <param name="isArray">Whether the value is an array.</param>
         /// <returns>
         /// The <see cref="ExifValue"/>.
         /// </returns>
-        private static ExifValue CreateNumber(ExifTag tag, Type type, bool isArray)
+        private static ExifValue CreateNumber(ExifTag tag, object value, bool isArray)
         {
+            Type type = value?.GetType();
+            if (type != null && type.IsArray)
+            {
+                type = type.GetElementType();
+            }
+
             if (type == null || type == typeof(ushort))
             {
-                return new ExifValue(tag, ExifDataType.Short, isArray);
+                return new ExifValue(tag, ExifDataType.Short, value, isArray);
             }
 
             if (type == typeof(short))
             {
-                return new ExifValue(tag, ExifDataType.SignedShort, isArray);
+                return new ExifValue(tag, ExifDataType.SignedShort, value, isArray);
             }
 
             if (type == typeof(uint))
             {
-                return new ExifValue(tag, ExifDataType.Long, isArray);
+                return new ExifValue(tag, ExifDataType.Long, value, isArray);
             }
 
-            return new ExifValue(tag, ExifDataType.SignedLong, isArray);
+            return new ExifValue(tag, ExifDataType.SignedLong, value, isArray);
         }
 
         /// <summary>
@@ -739,8 +691,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// <returns>The <see cref="string"/></returns>
         private string ToString(object value)
         {
-            string description = ExifTagDescriptionAttribute.GetDescription(this.Tag, value);
+            if (ExifTagDescriptionAttribute.GetDescription(this.Tag, value) is string description)
-            if (description != null)
             {
                 return description;
             }
@@ -788,7 +739,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         private int GetHashCode(ExifValue exif)
         {
             int hashCode = exif.Tag.GetHashCode() ^ exif.DataType.GetHashCode();
-            return hashCode ^ exif.exifValue?.GetHashCode() ?? hashCode;
+            return hashCode ^ exif.Value?.GetHashCode() ?? hashCode;
         }
     }
 }

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

@@ -2,8 +2,8 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Buffers.Binary;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Text;
 using SixLabors.ImageSharp.Primitives;
 
@@ -19,299 +19,28 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
         /// </summary>
         private const int StartIndex = 6;
 
-        /// <summary>
-        /// The collection if Image File Directory tags
-        /// </summary>
-        private static readonly ExifTag[] IfdTags =
-        {
-            ExifTag.SubfileType,
-            ExifTag.OldSubfileType,
-            ExifTag.ImageWidth,
-            ExifTag.ImageLength,
-            ExifTag.BitsPerSample,
-            ExifTag.Compression,
-            ExifTag.PhotometricInterpretation,
-            ExifTag.Thresholding,
-            ExifTag.CellWidth,
-            ExifTag.CellLength,
-            ExifTag.FillOrder,
-            ExifTag.DocumentName,
-            ExifTag.ImageDescription,
-            ExifTag.Make,
-            ExifTag.Model,
-            ExifTag.StripOffsets,
-            ExifTag.Orientation,
-            ExifTag.SamplesPerPixel,
-            ExifTag.RowsPerStrip,
-            ExifTag.StripByteCounts,
-            ExifTag.MinSampleValue,
-            ExifTag.MaxSampleValue,
-            ExifTag.XResolution,
-            ExifTag.YResolution,
-            ExifTag.PlanarConfiguration,
-            ExifTag.PageName,
-            ExifTag.XPosition,
-            ExifTag.YPosition,
-            ExifTag.FreeOffsets,
-            ExifTag.FreeByteCounts,
-            ExifTag.GrayResponseUnit,
-            ExifTag.GrayResponseCurve,
-            ExifTag.T4Options,
-            ExifTag.T6Options,
-            ExifTag.ResolutionUnit,
-            ExifTag.PageNumber,
-            ExifTag.ColorResponseUnit,
-            ExifTag.TransferFunction,
-            ExifTag.Software,
-            ExifTag.DateTime,
-            ExifTag.Artist,
-            ExifTag.HostComputer,
-            ExifTag.Predictor,
-            ExifTag.WhitePoint,
-            ExifTag.PrimaryChromaticities,
-            ExifTag.ColorMap,
-            ExifTag.HalftoneHints,
-            ExifTag.TileWidth,
-            ExifTag.TileLength,
-            ExifTag.TileOffsets,
-            ExifTag.TileByteCounts,
-            ExifTag.BadFaxLines,
-            ExifTag.CleanFaxData,
-            ExifTag.ConsecutiveBadFaxLines,
-            ExifTag.InkSet,
-            ExifTag.InkNames,
-            ExifTag.NumberOfInks,
-            ExifTag.DotRange,
-            ExifTag.TargetPrinter,
-            ExifTag.ExtraSamples,
-            ExifTag.SampleFormat,
-            ExifTag.SMinSampleValue,
-            ExifTag.SMaxSampleValue,
-            ExifTag.TransferRange,
-            ExifTag.ClipPath,
-            ExifTag.XClipPathUnits,
-            ExifTag.YClipPathUnits,
-            ExifTag.Indexed,
-            ExifTag.JPEGTables,
-            ExifTag.OPIProxy,
-            ExifTag.ProfileType,
-            ExifTag.FaxProfile,
-            ExifTag.CodingMethods,
-            ExifTag.VersionYear,
-            ExifTag.ModeNumber,
-            ExifTag.Decode,
-            ExifTag.DefaultImageColor,
-            ExifTag.T82ptions,
-            ExifTag.JPEGProc,
-            ExifTag.JPEGInterchangeFormat,
-            ExifTag.JPEGInterchangeFormatLength,
-            ExifTag.JPEGRestartInterval,
-            ExifTag.JPEGLosslessPredictors,
-            ExifTag.JPEGPointTransforms,
-            ExifTag.JPEGQTables,
-            ExifTag.JPEGDCTables,
-            ExifTag.JPEGACTables,
-            ExifTag.YCbCrCoefficients,
-            ExifTag.YCbCrSubsampling,
-            ExifTag.YCbCrSubsampling,
-            ExifTag.YCbCrPositioning,
-            ExifTag.ReferenceBlackWhite,
-            ExifTag.StripRowCounts,
-            ExifTag.XMP,
-            ExifTag.Rating,
-            ExifTag.RatingPercent,
-            ExifTag.ImageID,
-            ExifTag.CFARepeatPatternDim,
-            ExifTag.CFAPattern2,
-            ExifTag.BatteryLevel,
-            ExifTag.Copyright,
-            ExifTag.MDFileTag,
-            ExifTag.MDScalePixel,
-            ExifTag.MDLabName,
-            ExifTag.MDSampleInfo,
-            ExifTag.MDPrepDate,
-            ExifTag.MDPrepTime,
-            ExifTag.MDFileUnits,
-            ExifTag.PixelScale,
-            ExifTag.IntergraphPacketData,
-            ExifTag.IntergraphRegisters,
-            ExifTag.IntergraphMatrix,
-            ExifTag.ModelTiePoint,
-            ExifTag.SEMInfo,
-            ExifTag.ModelTransform,
-            ExifTag.ImageLayer,
-            ExifTag.FaxRecvParams,
-            ExifTag.FaxSubaddress,
-            ExifTag.FaxRecvTime,
-            ExifTag.ImageSourceData,
-            ExifTag.XPTitle,
-            ExifTag.XPComment,
-            ExifTag.XPAuthor,
-            ExifTag.XPKeywords,
-            ExifTag.XPSubject,
-            ExifTag.GDALMetadata,
-            ExifTag.GDALNoData
-        };
-
-        /// <summary>
-        /// The collection of Exif tags
-        /// </summary>
-        private static readonly ExifTag[] ExifTags =
-        {
-            ExifTag.ExposureTime,
-            ExifTag.FNumber,
-            ExifTag.ExposureProgram,
-            ExifTag.SpectralSensitivity,
-            ExifTag.ISOSpeedRatings,
-            ExifTag.OECF,
-            ExifTag.Interlace,
-            ExifTag.TimeZoneOffset,
-            ExifTag.SelfTimerMode,
-            ExifTag.SensitivityType,
-            ExifTag.StandardOutputSensitivity,
-            ExifTag.RecommendedExposureIndex,
-            ExifTag.ISOSpeed,
-            ExifTag.ISOSpeedLatitudeyyy,
-            ExifTag.ISOSpeedLatitudezzz,
-            ExifTag.ExifVersion,
-            ExifTag.DateTimeOriginal,
-            ExifTag.DateTimeDigitized,
-            ExifTag.OffsetTime,
-            ExifTag.OffsetTimeOriginal,
-            ExifTag.OffsetTimeDigitized,
-            ExifTag.ComponentsConfiguration,
-            ExifTag.CompressedBitsPerPixel,
-            ExifTag.ShutterSpeedValue,
-            ExifTag.ApertureValue,
-            ExifTag.BrightnessValue,
-            ExifTag.ExposureBiasValue,
-            ExifTag.MaxApertureValue,
-            ExifTag.SubjectDistance,
-            ExifTag.MeteringMode,
-            ExifTag.LightSource,
-            ExifTag.Flash,
-            ExifTag.FocalLength,
-            ExifTag.FlashEnergy2,
-            ExifTag.SpatialFrequencyResponse2,
-            ExifTag.Noise,
-            ExifTag.FocalPlaneXResolution2,
-            ExifTag.FocalPlaneYResolution2,
-            ExifTag.FocalPlaneResolutionUnit2,
-            ExifTag.ImageNumber,
-            ExifTag.SecurityClassification,
-            ExifTag.ImageHistory,
-            ExifTag.SubjectArea,
-            ExifTag.ExposureIndex2,
-            ExifTag.TIFFEPStandardID,
-            ExifTag.SensingMethod2,
-            ExifTag.MakerNote,
-            ExifTag.UserComment,
-            ExifTag.SubsecTime,
-            ExifTag.SubsecTimeOriginal,
-            ExifTag.SubsecTimeDigitized,
-            ExifTag.AmbientTemperature,
-            ExifTag.Humidity,
-            ExifTag.Pressure,
-            ExifTag.WaterDepth,
-            ExifTag.Acceleration,
-            ExifTag.CameraElevationAngle,
-            ExifTag.FlashpixVersion,
-            ExifTag.ColorSpace,
-            ExifTag.PixelXDimension,
-            ExifTag.PixelYDimension,
-            ExifTag.RelatedSoundFile,
-            ExifTag.FlashEnergy,
-            ExifTag.SpatialFrequencyResponse,
-            ExifTag.FocalPlaneXResolution,
-            ExifTag.FocalPlaneYResolution,
-            ExifTag.FocalPlaneResolutionUnit,
-            ExifTag.SubjectLocation,
-            ExifTag.ExposureIndex,
-            ExifTag.SensingMethod,
-            ExifTag.FileSource,
-            ExifTag.SceneType,
-            ExifTag.CFAPattern,
-            ExifTag.CustomRendered,
-            ExifTag.ExposureMode,
-            ExifTag.WhiteBalance,
-            ExifTag.DigitalZoomRatio,
-            ExifTag.FocalLengthIn35mmFilm,
-            ExifTag.SceneCaptureType,
-            ExifTag.GainControl,
-            ExifTag.Contrast,
-            ExifTag.Saturation,
-            ExifTag.Sharpness,
-            ExifTag.DeviceSettingDescription,
-            ExifTag.SubjectDistanceRange,
-            ExifTag.ImageUniqueID,
-            ExifTag.OwnerName,
-            ExifTag.SerialNumber,
-            ExifTag.LensInfo,
-            ExifTag.LensMake,
-            ExifTag.LensModel,
-            ExifTag.LensSerialNumber
-          };
-
-        /// <summary>
-        /// The collection of GPS tags
-        /// </summary>
-        private static readonly ExifTag[] GPSTags =
-        {
-            ExifTag.GPSVersionID,
-            ExifTag.GPSLatitudeRef,
-            ExifTag.GPSLatitude,
-            ExifTag.GPSLongitudeRef,
-            ExifTag.GPSLongitude,
-            ExifTag.GPSAltitudeRef,
-            ExifTag.GPSAltitude,
-            ExifTag.GPSTimestamp,
-            ExifTag.GPSSatellites,
-            ExifTag.GPSStatus,
-            ExifTag.GPSMeasureMode,
-            ExifTag.GPSDOP,
-            ExifTag.GPSSpeedRef,
-            ExifTag.GPSSpeed,
-            ExifTag.GPSTrackRef,
-            ExifTag.GPSTrack,
-            ExifTag.GPSImgDirectionRef,
-            ExifTag.GPSImgDirection,
-            ExifTag.GPSMapDatum,
-            ExifTag.GPSDestLatitudeRef,
-            ExifTag.GPSDestLatitude,
-            ExifTag.GPSDestLongitudeRef,
-            ExifTag.GPSDestLongitude,
-            ExifTag.GPSDestBearingRef,
-            ExifTag.GPSDestBearing,
-            ExifTag.GPSDestDistanceRef,
-            ExifTag.GPSDestDistance,
-            ExifTag.GPSProcessingMethod,
-            ExifTag.GPSAreaInformation,
-            ExifTag.GPSDateStamp,
-            ExifTag.GPSDifferential
-        };
-
         /// <summary>
         /// Which parts will be written.
         /// </summary>
         private ExifParts allowedParts;
-        private Collection<ExifValue> values;
+        private IList<ExifValue> values;
-        private Collection<int> dataOffsets;
+        private List<int> dataOffsets;
-        private Collection<int> ifdIndexes;
+        private List<int> ifdIndexes;
-        private Collection<int> exifIndexes;
+        private List<int> exifIndexes;
-        private Collection<int> gpsIndexes;
+        private List<int> gpsIndexes;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ExifWriter"/> class.
         /// </summary>
         /// <param name="values">The values.</param>
         /// <param name="allowedParts">The allowed parts.</param>
-        public ExifWriter(Collection<ExifValue> values, ExifParts allowedParts)
+        public ExifWriter(IList<ExifValue> values, ExifParts allowedParts)
         {
             this.values = values;
             this.allowedParts = allowedParts;
-            this.ifdIndexes = this.GetIndexes(ExifParts.IfdTags, IfdTags);
+            this.ifdIndexes = this.GetIndexes(ExifParts.IfdTags, ExifTags.Ifd);
-            this.exifIndexes = this.GetIndexes(ExifParts.ExifTags, ExifTags);
+            this.exifIndexes = this.GetIndexes(ExifParts.ExifTags, ExifTags.Exif);
-            this.gpsIndexes = this.GetIndexes(ExifParts.GPSTags, GPSTags);
+            this.gpsIndexes = this.GetIndexes(ExifParts.GPSTags, ExifTags.Gps);
         }
 
         /// <summary>
@@ -360,6 +89,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             length += 10 + 4 + 2;
 
             byte[] result = new byte[length];
+
             result[0] = (byte)'E';
             result[1] = (byte)'x';
             result[2] = (byte)'i';
@@ -377,17 +107,17 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
 
             if (exifLength > 0)
             {
-                this.values[exifIndex].Value = ifdOffset + ifdLength;
+                this.values[exifIndex] = this.values[exifIndex].WithValue(ifdOffset + ifdLength);
             }
 
             if (gpsLength > 0)
             {
-                this.values[gpsIndex].Value = ifdOffset + ifdLength + exifLength;
+                this.values[gpsIndex] = this.values[gpsIndex].WithValue(ifdOffset + ifdLength + exifLength);
             }
 
-            i = Write(BitConverter.GetBytes(ifdOffset), result, i);
+            i = WriteUInt32(ifdOffset, result, i);
             i = this.WriteHeaders(this.ifdIndexes, result, i);
-            i = Write(BitConverter.GetBytes(thumbnailOffset), result, i);
+            i = WriteUInt32(thumbnailOffset, result, i);
             i = this.WriteData(this.ifdIndexes, result, i);
 
             if (exifLength > 0)
@@ -402,19 +132,61 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 i = this.WriteData(this.gpsIndexes, result, i);
             }
 
-            Write(BitConverter.GetBytes((ushort)0), result, i);
+            WriteUInt16((ushort)0, result, i);
 
             return result;
         }
 
-        private static int Write(byte[] source, byte[] destination, int offset)
+        private static unsafe int WriteSingle(float value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(offset, 4), *((int*)&value));
+
+            return offset + 4;
+        }
+
+        private static unsafe int WriteDouble(double value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteInt64LittleEndian(destination.Slice(offset, 8), *((long*)&value));
+
+            return offset + 8;
+        }
+
+        private static int Write(ReadOnlySpan<byte> source, Span<byte> destination, int offset)
         {
-            Buffer.BlockCopy(source, 0, destination, offset, source.Length);
+            source.CopyTo(destination.Slice(offset, source.Length));
 
             return offset + source.Length;
         }
 
-        private int GetIndex(Collection<int> indexes, ExifTag tag)
+        private static int WriteInt16(short value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteInt16LittleEndian(destination.Slice(offset, 2), value);
+
+            return offset + 2;
+        }
+
+        private static int WriteUInt16(ushort value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteUInt16LittleEndian(destination.Slice(offset, 2), value);
+
+            return offset + 2;
+        }
+
+        private static int WriteUInt32(uint value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(offset, 4), value);
+
+            return offset + 4;
+        }
+
+        private static int WriteInt32(int value, Span<byte> destination, int offset)
+        {
+            BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(offset, 4), value);
+
+            return offset + 4;
+        }
+
+        private int GetIndex(IList<int> indexes, ExifTag tag)
         {
             foreach (int index in indexes)
             {
@@ -430,14 +202,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return newIndex;
         }
 
-        private Collection<int> GetIndexes(ExifParts part, ExifTag[] tags)
+        private List<int> GetIndexes(ExifParts part, ExifTag[] tags)
         {
             if (((int)this.allowedParts & (int)part) == 0)
             {
-                return new Collection<int>();
+                return new List<int>();
             }
 
-            Collection<int> result = new Collection<int>();
+            var result = new List<int>();
             for (int i = 0; i < this.values.Count; i++)
             {
                 ExifValue value = this.values[i];
@@ -457,7 +229,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return result;
         }
 
-        private uint GetLength(IEnumerable<int> indexes)
+        private uint GetLength(IList<int> indexes)
         {
             uint length = 0;
 
@@ -494,7 +266,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return newOffset;
         }
 
-        private int WriteData(Collection<int> indexes, byte[] destination, int offset)
+        private int WriteData(List<int> indexes, byte[] destination, int offset)
         {
             if (this.dataOffsets.Count == 0)
             {
@@ -509,7 +281,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                 ExifValue value = this.values[index];
                 if (value.Length > 4)
                 {
-                    Write(BitConverter.GetBytes(newOffset - StartIndex), destination, this.dataOffsets[i++]);
+                    WriteUInt32((uint)(newOffset - StartIndex), destination, this.dataOffsets[i++]);
                     newOffset = this.WriteValue(value, destination, newOffset);
                 }
             }
@@ -517,11 +289,11 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return newOffset;
         }
 
-        private int WriteHeaders(Collection<int> indexes, byte[] destination, int offset)
+        private int WriteHeaders(List<int> indexes, byte[] destination, int offset)
         {
-            this.dataOffsets = new Collection<int>();
+            this.dataOffsets = new List<int>();
 
-            int newOffset = Write(BitConverter.GetBytes((ushort)indexes.Count), destination, offset);
+            int newOffset = WriteUInt16((ushort)indexes.Count, destination, offset);
 
             if (indexes.Count == 0)
             {
@@ -531,9 +303,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             foreach (int index in indexes)
             {
                 ExifValue value = this.values[index];
-                newOffset = Write(BitConverter.GetBytes((ushort)value.Tag), destination, newOffset);
+                newOffset = WriteUInt16((ushort)value.Tag, destination, newOffset);
-                newOffset = Write(BitConverter.GetBytes((ushort)value.DataType), destination, newOffset);
+                newOffset = WriteUInt16((ushort)value.DataType, destination, newOffset);
-                newOffset = Write(BitConverter.GetBytes((uint)value.NumberOfComponents), destination, newOffset);
+                newOffset = WriteUInt32((uint)value.NumberOfComponents, destination, newOffset);
 
                 if (value.Length > 4)
                 {
@@ -550,23 +322,19 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
             return newOffset;
         }
 
-        private int WriteRational(Rational value, byte[] destination, int offset)
+        private static void WriteRational(Span<byte> destination, in Rational value)
         {
-            Write(BitConverter.GetBytes(value.Numerator), destination, offset);
+            BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(0, 4), value.Numerator);
-            Write(BitConverter.GetBytes(value.Denominator), destination, offset + 4);
+            BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(4, 4), value.Denominator);
-
-            return offset + 8;
         }
 
-        private int WriteSignedRational(SignedRational value, byte[] destination, int offset)
+        private static void WriteSignedRational(Span<byte> destination, in SignedRational value)
         {
-            Write(BitConverter.GetBytes(value.Numerator), destination, offset);
+            BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(0, 4), value.Numerator);
-            Write(BitConverter.GetBytes(value.Denominator), destination, offset + 4);
+            BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(4, 4), value.Denominator);
-
-            return offset + 8;
         }
 
-        private int WriteValue(ExifDataType dataType, object value, byte[] destination, int offset)
+        private int WriteValue(ExifDataType dataType, object value, Span<byte> destination, int offset)
         {
             switch (dataType)
             {
@@ -577,24 +345,26 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
                     destination[offset] = (byte)value;
                     return offset + 1;
                 case ExifDataType.DoubleFloat:
-                    return Write(BitConverter.GetBytes((double)value), destination, offset);
+                    return WriteDouble((double)value, destination, offset);
                 case ExifDataType.Short:
-                    return Write(BitConverter.GetBytes((ushort)value), destination, offset);
+                    return WriteUInt16((ushort)value, destination, offset);
                 case ExifDataType.Long:
-                    return Write(BitConverter.GetBytes((uint)value), destination, offset);
+                    return WriteUInt32((uint)value, destination, offset);
                 case ExifDataType.Rational:
-                    return this.WriteRational((Rational)value, destination, offset);
+                    WriteRational(destination.Slice(offset, 8), (Rational)value);
+                    return offset + 8;
                 case ExifDataType.SignedByte:
                     destination[offset] = unchecked((byte)((sbyte)value));
                     return offset + 1;
                 case ExifDataType.SignedLong:
-                    return Write(BitConverter.GetBytes((int)value), destination, offset);
+                    return WriteInt32((int)value, destination, offset);
                 case ExifDataType.SignedShort:
-                    return Write(BitConverter.GetBytes((short)value), destination, offset);
+                    return WriteInt16((short)value, destination, offset);
                 case ExifDataType.SignedRational:
-                    return this.WriteSignedRational((SignedRational)value, destination, offset);
+                    WriteSignedRational(destination.Slice(offset, 8), (SignedRational)value);
+                    return offset + 8;
                 case ExifDataType.SingleFloat:
-                    return Write(BitConverter.GetBytes((float)value), destination, offset);
+                    return WriteSingle((float)value, destination, offset);
                 default:
                     throw new NotImplementedException();
             }

src/ImageSharp/MetaData/Profiles/ICC/Curves/IccParametricCurve.cs

@@ -158,7 +158,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
                 return true;
             }
 
-            return obj is IccParametricCurve && this.Equals((IccParametricCurve)obj);
+            return obj is IccParametricCurve other && this.Equals(other);
         }
 
         /// <inheritdoc/>

src/ImageSharp/MetaData/Profiles/ICC/Curves/IccResponseCurve.cs

@@ -77,7 +77,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
                 return true;
             }
 
-            return obj is IccResponseCurve && this.Equals((IccResponseCurve)obj);
+            return obj is IccResponseCurve other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/Alpha8.cs

@@ -138,7 +138,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <returns>True if the object is equal to the packed vector.</returns>
         public override bool Equals(object obj)
         {
-            return (obj is Alpha8) && this.Equals((Alpha8)obj);
+            return obj is Alpha8 other && this.Equals(other);
         }
 
         /// <summary>

src/ImageSharp/PixelFormats/Bgr24.cs

@@ -59,7 +59,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            return obj?.GetType() == typeof(Bgr24) && this.Equals((Bgr24)obj);
+            return obj is Bgr24 other && this.Equals(other);
         }
 
         /// <inheritdoc/>

src/ImageSharp/PixelFormats/Bgra32.cs

@@ -104,7 +104,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj) => obj?.GetType() == typeof(Bgra32) && this.Equals((Bgra32)obj);
+        public override bool Equals(object obj) => obj is Bgra32 other && this.Equals(other);
 
         /// <inheritdoc/>
         public override int GetHashCode()

src/ImageSharp/PixelFormats/Bgra4444.cs

@@ -156,7 +156,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is Bgra4444) && this.Equals((Bgra4444)obj);
+            return obj is Bgra4444 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/Bgra5551.cs

@@ -156,7 +156,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is Bgra5551) && this.Equals((Bgra5551)obj);
+            return obj is Bgra5551 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/ColorBuilder{TPixel}.cs

@@ -32,8 +32,8 @@ namespace SixLabors.ImageSharp.PixelFormats
                 throw new ArgumentException("Hexadecimal string is not in the correct format.", nameof(hex));
             }
 
-            TPixel result = default(TPixel);
+            TPixel result = default;
-            Rgba32 rgba = new Rgba32(
+            var rgba = new Rgba32(
                 (byte)(packedValue >> 24),
                 (byte)(packedValue >> 16),
                 (byte)(packedValue >> 8),
@@ -62,7 +62,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <returns>Returns a <typeparamref name="TPixel"/> that represents the color defined by the provided RGBA values.</returns>
         public static TPixel FromRGBA(byte red, byte green, byte blue, byte alpha)
         {
-            TPixel color = default(TPixel);
+            TPixel color = default;
             color.PackFromRgba32(new Rgba32(red, green, blue, alpha));
             return color;
         }

src/ImageSharp/PixelFormats/HalfVector4.cs

@@ -191,7 +191,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is HalfVector4) && this.Equals((HalfVector4)obj);
+            return obj is HalfVector4 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/NamedColors{TPixel}.cs

@@ -735,7 +735,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         private static TPixel[] GetWebSafePalette()
         {
             Rgba32[] constants = ColorConstants.WebSafeColors;
-            TPixel[] safe = new TPixel[constants.Length + 1];
+            var safe = new TPixel[constants.Length + 1];
 
             Span<byte> constantsBytes = constants.AsSpan().NonPortableCast<Rgba32, byte>();
             PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(constantsBytes, safe, constants.Length);

src/ImageSharp/PixelFormats/NormalizedByte2.cs

@@ -194,7 +194,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is NormalizedByte2) && this.Equals((NormalizedByte2)obj);
+            return obj is NormalizedByte2 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/NormalizedByte4.cs

@@ -187,7 +187,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is NormalizedByte4) && this.Equals((NormalizedByte4)obj);
+            return obj is NormalizedByte4 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/NormalizedShort4.cs

@@ -189,7 +189,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is NormalizedShort4) && this.Equals((NormalizedShort4)obj);
+            return obj is NormalizedShort4 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/Rgb24.cs

@@ -60,7 +60,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            return obj?.GetType() == typeof(Rgb24) && this.Equals((Rgb24)obj);
+            return obj is Rgb24 other && this.Equals(other);
         }
 
         /// <inheritdoc/>

src/ImageSharp/PixelFormats/RgbaVector.PixelOperations.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Numerics;
-using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.PixelFormats
 {

src/ImageSharp/PixelFormats/RgbaVector.cs

@@ -304,7 +304,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            return (obj is RgbaVector) && this.Equals((RgbaVector)obj);
+            return obj is RgbaVector other && this.Equals(other);
         }
 
         /// <inheritdoc/>

src/ImageSharp/PixelFormats/Short2.cs

@@ -190,7 +190,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is Short2) && this.Equals((Short2)obj);
+            return obj is Short2 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/PixelFormats/Short4.cs

@@ -185,7 +185,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
-            return (obj is Short4) && this == (Short4)obj;
+            return obj is Short4 other && this.Equals(other);
         }
 
         /// <inheritdoc />

src/ImageSharp/Primitives/DenseMatrix{T}.cs

@@ -207,7 +207,7 @@ namespace SixLabors.ImageSharp.Primitives
         }
 
         /// <inheritdoc/>
-        public override bool Equals(object obj) => obj is DenseMatrix<T> matrix && this.Equals(matrix);
+        public override bool Equals(object obj) => obj is DenseMatrix<T> other && this.Equals(other);
 
         /// <inheritdoc/>
         public override int GetHashCode() => this.Data.GetHashCode();

src/ImageSharp/Primitives/LongRational.cs

@@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.Primitives
     /// <remarks>
     /// This is a very simplified implementation of a rational number designed for use with metadata only.
     /// </remarks>
-    internal struct LongRational : IEquatable<LongRational>
+    internal readonly struct LongRational : IEquatable<LongRational>
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="LongRational"/> struct.
@@ -26,126 +26,25 @@ namespace SixLabors.ImageSharp.Primitives
         /// The number below the line in a vulgar fraction; a divisor.
         /// </param>
         public LongRational(long numerator, long denominator)
-          : this(numerator, denominator, false)
-        {
-        }
-
-        /// <summary>
-        /// Initializes a new instance of the <see cref="LongRational"/> struct.
-        /// </summary>
-        /// <param name="numerator">
-        /// The number above the line in a vulgar fraction showing how many of the parts
-        /// indicated by the denominator are taken.
-        /// </param>
-        /// <param name="denominator">
-        /// The number below the line in a vulgar fraction; a divisor.
-        /// </param>
-        /// <param name="simplify">
-        /// Whether to attempt to simplify the fractional parts.
-        /// </param>
-        public LongRational(long numerator, long denominator, bool simplify)
-            : this()
         {
             this.Numerator = numerator;
             this.Denominator = denominator;
-
-            if (simplify)
-            {
-                this.Simplify();
-            }
-        }
-
-        /// <summary>
-        /// Initializes a new instance of the <see cref="LongRational"/> struct.
-        /// </summary>
-        /// <param name="value">The <see cref="double"/> to create the instance from.</param>
-        /// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
-        public LongRational(double value, bool bestPrecision)
-            : this()
-        {
-            if (double.IsNaN(value))
-            {
-                this.Numerator = this.Denominator = 0;
-                return;
-            }
-
-            if (double.IsPositiveInfinity(value))
-            {
-                this.Numerator = 1;
-                this.Denominator = 0;
-                return;
-            }
-
-            if (double.IsNegativeInfinity(value))
-            {
-                this.Numerator = -1;
-                this.Denominator = 0;
-                return;
-            }
-
-            this.Numerator = 1;
-            this.Denominator = 1;
-
-            double val = Math.Abs(value);
-            double df = this.Numerator / (double)this.Denominator;
-            double epsilon = bestPrecision ? double.Epsilon : .000001;
-
-            while (Math.Abs(df - val) > epsilon)
-            {
-                if (df < val)
-                {
-                    this.Numerator++;
-                }
-                else
-                {
-                    this.Denominator++;
-                    this.Numerator = (int)(val * this.Denominator);
-                }
-
-                df = this.Numerator / (double)this.Denominator;
-            }
-
-            if (value < 0.0)
-            {
-                this.Numerator *= -1;
-            }
-
-            this.Simplify();
         }
 
         /// <summary>
         /// Gets the numerator of a number.
         /// </summary>
-        public long Numerator
+        public long Numerator { get; }
-        {
-            get;
-            private set;
-        }
 
         /// <summary>
         /// Gets the denominator of a number.
         /// </summary>
-        public long Denominator
+        public long Denominator { get; }
-        {
-            get;
-            private set;
-        }
 
         /// <summary>
         /// Gets a value indicating whether this instance is indeterminate.
         /// </summary>
-        public bool IsIndeterminate
+        public bool IsIndeterminate => this.Denominator == 0 && this.Numerator == 0;
-        {
-            get
-            {
-                if (this.Denominator != 0)
-                {
-                    return false;
-                }
-
-                return this.Numerator == 0;
-            }
-        }
 
         /// <summary>
         /// Gets a value indicating whether this instance is an integer (n, 1)
@@ -155,76 +54,28 @@ namespace SixLabors.ImageSharp.Primitives
         /// <summary>
         /// Gets a value indicating whether this instance is equal to negative infinity (-1, 0)
         /// </summary>
-        public bool IsNegativeInfinity
+        public bool IsNegativeInfinity => this.Denominator == 0 && this.Numerator == -1;
-        {
-            get
-            {
-                if (this.Denominator != 0)
-                {
-                    return false;
-                }
-
-                return this.Numerator == -1;
-            }
-        }
 
         /// <summary>
         /// Gets a value indicating whether this instance is equal to positive infinity (1, 0)
         /// </summary>
-        public bool IsPositiveInfinity
+        public bool IsPositiveInfinity => this.Denominator == 0 && this.Numerator == 1;
-        {
-            get
-            {
-                if (this.Denominator != 0)
-                {
-                    return false;
-                }
-
-                return this.Numerator == 1;
-            }
-        }
 
         /// <summary>
         /// Gets a value indicating whether this instance is equal to 0 (0, 1)
         /// </summary>
-        public bool IsZero
+        public bool IsZero => this.Denominator == 1 && this.Numerator == 0;
-        {
-            get
-            {
-                if (this.Denominator != 1)
-                {
-                    return false;
-                }
-
-                return this.Numerator == 0;
-            }
-        }
 
         /// <inheritdoc/>
         public bool Equals(LongRational other)
         {
-            if (this.Denominator == other.Denominator)
+            return this.Numerator == other.Numerator && this.Denominator == other.Denominator;
-            {
-                return this.Numerator == other.Numerator;
-            }
-
-            if (this.Numerator == 0 && this.Denominator == 0)
-            {
-                return other.Numerator == 0 && other.Denominator == 0;
-            }
-
-            if (other.Numerator == 0 && other.Denominator == 0)
-            {
-                return this.Numerator == 0 && this.Denominator == 0;
-            }
-
-            return (this.Numerator * other.Denominator) == (this.Denominator * other.Numerator);
         }
 
         /// <inheritdoc/>
         public override int GetHashCode()
         {
-            return this.GetHashCode(this);
+            return ((this.Numerator * 397) ^ this.Denominator).GetHashCode();
         }
 
         /// <inheritdoc/>
@@ -268,86 +119,108 @@ namespace SixLabors.ImageSharp.Primitives
                 return this.Numerator.ToString(provider);
             }
 
-            StringBuilder sb = new StringBuilder();
+            var sb = new StringBuilder();
             sb.Append(this.Numerator.ToString(provider));
-            sb.Append("/");
+            sb.Append('/');
             sb.Append(this.Denominator.ToString(provider));
             return sb.ToString();
         }
 
         /// <summary>
-        /// Finds the greatest common divisor of two <see cref="long"/> values.
+        /// Create a new instance of the <see cref="LongRational"/> struct from a double value.
         /// </summary>
-        /// <param name="left">The first value</param>
+        /// <param name="value">The <see cref="double"/> to create the instance from.</param>
-        /// <param name="right">The second value</param>
+        /// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
-        /// <returns>The <see cref="long"/></returns>
+        public static LongRational FromDouble(double value, bool bestPrecision)
-        private static long GreatestCommonDivisor(long left, long right)
         {
-            return right == 0 ? left : GreatestCommonDivisor(right, left % right);
+            if (double.IsNaN(value))
-        }
+            {
+                return new LongRational(0, 0);
+            }
 
-        /// <summary>
+            if (double.IsPositiveInfinity(value))
-        /// Simplifies the <see cref="LongRational"/>
-        /// </summary>
-        private void Simplify()
-        {
-            if (this.IsIndeterminate)
             {
-                return;
+                return new LongRational(1, 0);
             }
 
-            if (this.IsNegativeInfinity)
+            if (double.IsNegativeInfinity(value))
             {
-                return;
+                return new LongRational(-1, 0);
             }
 
-            if (this.IsPositiveInfinity)
+            long numerator = 1;
+            long denominator = 1;
+
+            double val = Math.Abs(value);
+            double df = numerator / (double)denominator;
+            double epsilon = bestPrecision ? double.Epsilon : .000001;
+
+            while (Math.Abs(df - val) > epsilon)
             {
-                return;
+                if (df < val)
+                {
+                    numerator++;
+                }
+                else
+                {
+                    denominator++;
+                    numerator = (int)(val * denominator);
+                }
+
+                df = numerator / (double)denominator;
             }
 
-            if (this.IsInteger)
+            if (value < 0.0)
             {
-                return;
+                numerator *= -1;
             }
 
-            if (this.IsZero)
+            return new LongRational(numerator, denominator).Simplify();
+        }
+
+        /// <summary>
+        /// Finds the greatest common divisor of two <see cref="long"/> values.
+        /// </summary>
+        /// <param name="left">The first value</param>
+        /// <param name="right">The second value</param>
+        /// <returns>The <see cref="long"/></returns>
+        private static long GreatestCommonDivisor(long left, long right)
+        {
+            return right == 0 ? left : GreatestCommonDivisor(right, left % right);
+        }
+
+        /// <summary>
+        /// Simplifies the <see cref="LongRational"/>
+        /// </summary>
+        public LongRational Simplify()
+        {
+            if (this.IsIndeterminate ||
+                this.IsNegativeInfinity ||
+                this.IsPositiveInfinity ||
+                this.IsInteger ||
+                this.IsZero)
             {
-                return;
+                return this;
             }
 
             if (this.Numerator == 0)
             {
-                this.Denominator = 0;
+                return new LongRational(0, 0);
-                return;
             }
 
             if (this.Numerator == this.Denominator)
             {
-                this.Numerator = 1;
+                return new LongRational(1, 1);
-                this.Denominator = 1;
             }
 
             long gcd = GreatestCommonDivisor(Math.Abs(this.Numerator), Math.Abs(this.Denominator));
+
             if (gcd > 1)
             {
-                this.Numerator = this.Numerator / gcd;
+                return new LongRational(this.Numerator / gcd, this.Denominator / gcd);
-                this.Denominator = this.Denominator / gcd;
             }
-        }
 
-        /// <summary>
+            return this;
-        /// Returns the hash code for this instance.
-        /// </summary>
-        /// <param name="rational">
-        /// The instance of <see cref="LongRational"/> to return the hash code for.
-        /// </param>
-        /// <returns>
-        /// A 32-bit signed integer that is the hash code for this instance.
-        /// </returns>
-        private int GetHashCode(LongRational rational)
-        {
-            return ((rational.Numerator * 397) ^ rational.Denominator).GetHashCode();
         }
     }
 }

src/ImageSharp/Primitives/Rational.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Primitives
     /// <remarks>
     /// This is a very simplified implementation of a rational number designed for use with metadata only.
     /// </remarks>
-    public struct Rational : IEquatable<Rational>
+    public readonly struct Rational : IEquatable<Rational>
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Rational"/> struct.
@@ -41,10 +41,18 @@ namespace SixLabors.ImageSharp.Primitives
         /// <param name="simplify">Specified if the rational should be simplified.</param>
         public Rational(uint numerator, uint denominator, bool simplify)
         {
-            LongRational rational = new LongRational(numerator, denominator, simplify);
+            if (simplify)
+            {
+                LongRational rational = new LongRational(numerator, denominator).Simplify();
 
-            this.Numerator = (uint)rational.Numerator;
+                this.Numerator = (uint)rational.Numerator;
-            this.Denominator = (uint)rational.Denominator;
+                this.Denominator = (uint)rational.Denominator;
+            }
+            else
+            {
+                this.Numerator = numerator;
+                this.Denominator = denominator;
+            }
         }
 
         /// <summary>
@@ -63,7 +71,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
         public Rational(double value, bool bestPrecision)
         {
-            LongRational rational = new LongRational(Math.Abs(value), bestPrecision);
+            var rational = LongRational.FromDouble(Math.Abs(value), bestPrecision);
 
             this.Numerator = (uint)rational.Numerator;
             this.Denominator = (uint)rational.Denominator;
@@ -129,19 +137,14 @@ namespace SixLabors.ImageSharp.Primitives
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (obj is Rational)
+            return obj is Rational other && this.Equals(other);
-            {
-                return this.Equals((Rational)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>
         public bool Equals(Rational other)
         {
-            LongRational left = new LongRational(this.Numerator, this.Denominator);
+            var left = new LongRational(this.Numerator, this.Denominator);
-            LongRational right = new LongRational(other.Numerator, other.Denominator);
+            var right = new LongRational(other.Numerator, other.Denominator);
 
             return left.Equals(right);
         }
@@ -149,7 +152,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <inheritdoc/>
         public override int GetHashCode()
         {
-            LongRational self = new LongRational(this.Numerator, this.Denominator);
+            var self = new LongRational(this.Numerator, this.Denominator);
             return self.GetHashCode();
         }
 
@@ -180,7 +183,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <returns>The <see cref="string"/></returns>
         public string ToString(IFormatProvider provider)
         {
-            LongRational rational = new LongRational(this.Numerator, this.Denominator);
+            var rational = new LongRational(this.Numerator, this.Denominator);
             return rational.ToString(provider);
         }
     }

src/ImageSharp/Primitives/SignedRational.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Primitives
     /// <remarks>
     /// This is a very simplified implementation of a rational number designed for use with metadata only.
     /// </remarks>
-    public struct SignedRational : IEquatable<SignedRational>
+    public readonly struct SignedRational : IEquatable<SignedRational>
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="SignedRational"/> struct.
@@ -41,10 +41,18 @@ namespace SixLabors.ImageSharp.Primitives
         /// <param name="simplify">Specified if the rational should be simplified.</param>
         public SignedRational(int numerator, int denominator, bool simplify)
         {
-            LongRational rational = new LongRational(numerator, denominator, simplify);
+            if (simplify)
+            {
+                LongRational rational = new LongRational(numerator, denominator).Simplify();
 
-            this.Numerator = (int)rational.Numerator;
+                this.Numerator = (int)rational.Numerator;
-            this.Denominator = (int)rational.Denominator;
+                this.Denominator = (int)rational.Denominator;
+            }
+            else
+            {
+                this.Numerator = numerator;
+                this.Denominator = denominator;
+            }
         }
 
         /// <summary>
@@ -63,7 +71,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
         public SignedRational(double value, bool bestPrecision)
         {
-            LongRational rational = new LongRational(value, bestPrecision);
+            var rational = LongRational.FromDouble(value, bestPrecision);
 
             this.Numerator = (int)rational.Numerator;
             this.Denominator = (int)rational.Denominator;
@@ -129,19 +137,14 @@ namespace SixLabors.ImageSharp.Primitives
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
-            if (obj is SignedRational)
+            return obj is SignedRational other && this.Equals(other);
-            {
-                return this.Equals((SignedRational)obj);
-            }
-
-            return false;
         }
 
         /// <inheritdoc/>
         public bool Equals(SignedRational other)
         {
-            LongRational left = new LongRational(this.Numerator, this.Denominator);
+            var left = new LongRational(this.Numerator, this.Denominator);
-            LongRational right = new LongRational(other.Numerator, other.Denominator);
+            var right = new LongRational(other.Numerator, other.Denominator);
 
             return left.Equals(right);
         }
@@ -149,7 +152,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <inheritdoc/>
         public override int GetHashCode()
         {
-            LongRational self = new LongRational(this.Numerator, this.Denominator);
+            var self = new LongRational(this.Numerator, this.Denominator);
             return self.GetHashCode();
         }
 
@@ -180,7 +183,7 @@ namespace SixLabors.ImageSharp.Primitives
         /// <returns>The <see cref="string"/></returns>
         public string ToString(IFormatProvider provider)
         {
-            LongRational rational = new LongRational(this.Numerator, this.Denominator);
+            var rational = new LongRational(this.Numerator, this.Denominator);
             return rational.ToString(provider);
         }
     }

tests/ImageSharp.Tests/Memory/SpanUtilityTests.cs

@@ -66,7 +66,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<TestStructs.Foo>(source, 1, source.Length - 1);
                 var apDest = new Span<TestStructs.Foo>(dest, 1, dest.Length - 1);
 
-                SpanHelper.Copy(apSource, apDest, count - 1);
+                apSource.Slice(0, count - 1).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
                 AssertNotDefault(dest, 1);
@@ -89,7 +89,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<TestStructs.AlignedFoo>(source, 1, source.Length - 1);
                 var apDest = new Span<TestStructs.AlignedFoo>(dest, 1, dest.Length - 1);
 
-                SpanHelper.Copy(apSource, apDest, count - 1);
+                apSource.Slice(0, count - 1).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
                 AssertNotDefault(dest, 1);
@@ -112,7 +112,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<int>(source, 1, source.Length - 1);
                 var apDest = new Span<int>(dest, 1, dest.Length - 1);
 
-                SpanHelper.Copy(apSource, apDest, count - 1);
+                apSource.Slice(0, count - 1).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
                 AssertNotDefault(dest, 1);
@@ -136,7 +136,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<TestStructs.Foo>(source, 1, source.Length - 1);
                 var apDest = new Span<byte>(dest, sizeof(TestStructs.Foo), dest.Length - sizeof(TestStructs.Foo));
 
-                SpanHelper.Copy(apSource.AsBytes(), apDest, (count - 1) * sizeof(TestStructs.Foo));
+                apSource.AsBytes().Slice(0, (count - 1) * sizeof(TestStructs.Foo)).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
 
@@ -159,7 +159,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<TestStructs.AlignedFoo>(source, 1, source.Length - 1);
                 var apDest = new Span<byte>(dest, sizeof(TestStructs.AlignedFoo), dest.Length - sizeof(TestStructs.AlignedFoo));
 
-                SpanHelper.Copy(apSource.AsBytes(), apDest, (count - 1) * sizeof(TestStructs.AlignedFoo));
+                apSource.AsBytes().Slice(0, (count - 1) * sizeof(TestStructs.AlignedFoo)).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
 
@@ -182,7 +182,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 var apSource = new Span<int>(source);
                 var apDest = new Span<byte>(dest);
 
-                SpanHelper.Copy(apSource.AsBytes(), apDest, count * sizeof(int));
+                apSource.AsBytes().Slice(0, count * sizeof(int)).CopyTo(apDest);
 
                 AssertNotDefault(source, 1);
 
@@ -198,12 +198,12 @@ namespace SixLabors.ImageSharp.Tests.Memory
             {
                 int srcCount = count * sizeof(TestStructs.Foo);
                 byte[] source = CreateTestBytes(srcCount);
-                TestStructs.Foo[] dest = new TestStructs.Foo[count + 2];
+                var dest = new TestStructs.Foo[count + 2];
 
                 var apSource = new Span<byte>(source);
                 var apDest = new Span<TestStructs.Foo>(dest);
 
-                SpanHelper.Copy(apSource, apDest.AsBytes(), count * sizeof(TestStructs.Foo));
+                apSource.Slice(0, count * sizeof(TestStructs.Foo)).CopyTo(apDest.AsBytes());
 
                 AssertNotDefault(source, sizeof(TestStructs.Foo) + 1);
                 AssertNotDefault(dest, 1);

tests/ImageSharp.Tests/MetaData/ImagePropertyTests.cs

@@ -18,13 +18,11 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void AreEqual()
         {
-            ImageProperty property1 = new ImageProperty("Foo", "Bar");
+            var property1 = new ImageProperty("Foo", "Bar");
-            ImageProperty property2 = new ImageProperty("Foo", "Bar");
+            var property2 = new ImageProperty("Foo", "Bar");
-            ImageProperty property3 = null;
 
             Assert.Equal(property1, property2);
             Assert.True(property1 == property2);
-            Assert.Null(property3);
         }
 
         /// <summary>
@@ -33,15 +31,13 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void AreNotEqual()
         {
-            ImageProperty property1 = new ImageProperty("Foo", "Bar");
+            var property1 = new ImageProperty("Foo", "Bar");
-            ImageProperty property2 = new ImageProperty("Foo", "Foo");
+            var property2 = new ImageProperty("Foo", "Foo");
-            ImageProperty property3 = new ImageProperty("Bar", "Bar");
+            var property3 = new ImageProperty("Bar", "Bar");
-            ImageProperty property4 = new ImageProperty("Foo", null);
+            var property4 = new ImageProperty("Foo", null);
 
             Assert.False(property1.Equals("Foo"));
 
-            Assert.NotNull(property1);
-
             Assert.NotEqual(property1, property2);
             Assert.True(property1 != property2);
 
@@ -66,7 +62,7 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void ConstructorAssignsProperties()
         {
-            ImageProperty property = new ImageProperty("Foo", null);
+            var property = new ImageProperty("Foo", null);
             Assert.Equal("Foo", property.Name);
             Assert.Null(property.Value);
 

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

@@ -141,7 +141,7 @@ namespace SixLabors.ImageSharp.Tests
             ExifValue value = image.MetaData.ExifProfile.GetValue(ExifTag.Software);
             TestValue(value, "ImageSharp");
 
-            Assert.Throws<ArgumentException>(() => { value.Value = 15; });
+            Assert.Throws<ArgumentException>(() => { value.WithValue(15); });
 
             image.MetaData.ExifProfile.SetValue(ExifTag.ShutterSpeedValue, new SignedRational(75.55));
 
@@ -149,7 +149,7 @@ namespace SixLabors.ImageSharp.Tests
 
             TestValue(value, new SignedRational(7555, 100));
 
-            Assert.Throws<ArgumentException>(() => { value.Value = 75; });
+            Assert.Throws<ArgumentException>(() => { value.WithValue(75); });
 
             image.MetaData.ExifProfile.SetValue(ExifTag.XResolution, new Rational(150.0));
 
@@ -159,7 +159,7 @@ namespace SixLabors.ImageSharp.Tests
             value = image.MetaData.ExifProfile.GetValue(ExifTag.XResolution);
             TestValue(value, new Rational(150, 1));
 
-            Assert.Throws<ArgumentException>(() => { value.Value = "ImageSharp"; });
+            Assert.Throws<ArgumentException>(() => { value.WithValue("ImageSharp"); });
 
             image.MetaData.ExifProfile.SetValue(ExifTag.ReferenceBlackWhite, null);
 
@@ -209,11 +209,11 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void Syncs()
         {
-            ExifProfile exifProfile = new ExifProfile();
+            var exifProfile = new ExifProfile();
             exifProfile.SetValue(ExifTag.XResolution, new Rational(200));
             exifProfile.SetValue(ExifTag.YResolution, new Rational(300));
 
-            ImageMetaData metaData = new ImageMetaData();
+            var metaData = new ImageMetaData();
             metaData.ExifProfile = exifProfile;
             metaData.HorizontalResolution = 200;
             metaData.VerticalResolution = 300;
@@ -255,17 +255,17 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void WriteTooLargeProfile()
         {
-            StringBuilder junk = new StringBuilder();
+            var junk = new StringBuilder();
             for (int i = 0; i < 65500; i++)
             {
                 junk.Append("I");
             }
 
-            Image<Rgba32> image = new Image<Rgba32>(100, 100);
+            var image = new Image<Rgba32>(100, 100);
             image.MetaData.ExifProfile = new ExifProfile();
             image.MetaData.ExifProfile.SetValue(ExifTag.ImageDescription, junk.ToString());
 
-            using (MemoryStream memStream = new MemoryStream())
+            using (var memStream = new MemoryStream())
             {
                 Assert.Throws<ImageFormatException>(() => image.SaveAsJpeg(memStream));
             }
@@ -274,6 +274,9 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void ExifTypeUndefined()
         {
+            // This image contains an 802 byte EXIF profile
+            // It has a tag with an index offset of 18,481,152 bytes (overrunning the data)
+
             Image<Rgba32> image = TestFile.Create(TestImages.Jpeg.Progressive.Bad.ExifUndefType).CreateImage();
             Assert.NotNull(image);
 

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

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Collections.ObjectModel;
+using System.Collections.Generic;
 using SixLabors.ImageSharp.MetaData.Profiles.Exif;
 using Xunit;
 
@@ -12,10 +12,9 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void Read_DataIsEmpty_ReturnsEmptyCollection()
         {
-            ExifReader reader = new ExifReader();
+            var reader = new ExifReader(new byte[] { });
-            byte[] data = new byte[] { };
 
-            Collection<ExifValue> result = reader.Read(data);
+            IList<ExifValue> result = reader.ReadValues();
 
             Assert.Equal(0, result.Count);
         }
@@ -23,10 +22,9 @@ namespace SixLabors.ImageSharp.Tests
         [Fact]
         public void Read_DataIsMinimal_ReturnsEmptyCollection()
         {
-            ExifReader reader = new ExifReader();
+            var reader = new ExifReader(new byte[] { 69, 120, 105, 102, 0, 0 });
-            byte[] data = new byte[] { 69, 120, 105, 102, 0, 0 };
 
-            Collection<ExifValue> result = reader.Read(data);
+            IList<ExifValue> result = reader.ReadValues();
 
             Assert.Equal(0, result.Count);
         }