Improve decoders - performance and memory usage.

Implement Identify methods and add tests.
Report not supported Predictor and SampleFormat features.

src/ImageSharp/Formats/Tiff/Compression/CompressionFactory.cs

@@ -1,42 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.IO;
-
-namespace SixLabors.ImageSharp.Formats.Tiff
-{
-    internal static class CompressionFactory
-    {
-        /// <summary>
-        /// Decompresses an image block from the input stream into the specified buffer.
-        /// </summary>
-        /// <param name="stream">The input stream.</param>
-        /// <param name="compressionType">Type of the compression.</param>
-        /// <param name="offset">The offset within the file of the image block.</param>
-        /// <param name="byteCount">The size (in bytes) of the compressed data.</param>
-        /// <param name="buffer">The buffer to write the uncompressed data.</param>
-        public static void DecompressImageBlock(Stream stream, TiffCompressionType compressionType, uint offset, uint byteCount, byte[] buffer)
-        {
-            stream.Seek(offset, SeekOrigin.Begin);
-
-            switch (compressionType)
-            {
-                case TiffCompressionType.None:
-                    NoneTiffCompression.Decompress(stream, (int)byteCount, buffer);
-                    break;
-                case TiffCompressionType.PackBits:
-                    PackBitsTiffCompression.Decompress(stream, (int)byteCount, buffer);
-                    break;
-                case TiffCompressionType.Deflate:
-                    DeflateTiffCompression.Decompress(stream, (int)byteCount, buffer);
-                    break;
-                case TiffCompressionType.Lzw:
-                    LzwTiffCompression.Decompress(stream, (int)byteCount, buffer);
-                    break;
-                default:
-                    throw new InvalidOperationException();
-            }
-        }
-    }
-}

src/ImageSharp/Formats/Tiff/Compression/DeflateTiffCompression.cs

@@ -4,7 +4,7 @@
 using System;
 using System.IO;
 using System.IO.Compression;
-using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
@@ -14,16 +14,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <remarks>
     /// Note that the 'OldDeflate' compression type is identical to the 'Deflate' compression type.
     /// </remarks>
-    internal static class DeflateTiffCompression
+    internal class DeflateTiffCompression : TiffBaseCompression
     {
-        /// <summary>
-        /// Decompresses image data into the supplied buffer.
-        /// </summary>
-        /// <param name="stream">The <see cref="Stream"/> to read image data from.</param>
-        /// <param name="byteCount">The number of bytes to read from the input stream.</param>
-        /// <param name="buffer">The output buffer for uncompressed data.</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Decompress(Stream stream, int byteCount, byte[] buffer)
+        public DeflateTiffCompression(MemoryAllocator allocator)
+            : base(allocator)
+        {
+        }
+
+        /// <inheritdoc/>
+        public override void Decompress(Stream stream, int byteCount, Span<byte> buffer)
         {
             // Read the 'zlib' header information
             int cmf = stream.ReadByte();
@@ -47,8 +46,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
             // The subsequent data is the Deflate compressed data (except for the last four bytes of checksum)
             int headerLength = fdict ? 10 : 6;
-            SubStream subStream = new SubStream(stream, byteCount - headerLength);
-            using (DeflateStream deflateStream = new DeflateStream(subStream, CompressionMode.Decompress, true))
+            var subStream = new SubStream(stream, byteCount - headerLength);
+            using (var deflateStream = new DeflateStream(subStream, CompressionMode.Decompress, true))
             {
                 deflateStream.ReadFull(buffer);
             }

src/ImageSharp/Formats/Tiff/Compression/LzwTiffCompression.cs

@@ -1,26 +1,26 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.IO;
-using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using LZW compression.
     /// </summary>
-    internal static class LzwTiffCompression
+    internal class LzwTiffCompression : TiffBaseCompression
     {
-        /// <summary>
-        /// Decompresses image data into the supplied buffer.
-        /// </summary>
-        /// <param name="stream">The <see cref="Stream"/> to read image data from.</param>
-        /// <param name="byteCount">The number of bytes to read from the input stream.</param>
-        /// <param name="buffer">The output buffer for uncompressed data.</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Decompress(Stream stream, int byteCount, byte[] buffer)
+        public LzwTiffCompression(MemoryAllocator allocator)
+            : base(allocator)
         {
-            SubStream subStream = new SubStream(stream, byteCount);
+        }
+
+        /// <inheritdoc/>
+        public override void Decompress(Stream stream, int byteCount, Span<byte> buffer)
+        {
+            var subStream = new SubStream(stream, byteCount);
             using (var decoder = new TiffLzwDecoder(subStream))
             {
                 decoder.DecodePixels(buffer.Length, 8, buffer);

src/ImageSharp/Formats/Tiff/Compression/NoneTiffCompression.cs

@@ -1,24 +1,24 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.IO;
-using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
     /// <summary>
     /// Class to handle cases where TIFF image data is not compressed.
     /// </summary>
-    internal static class NoneTiffCompression
+    internal class NoneTiffCompression : TiffBaseCompression
     {
-        /// <summary>
-        /// Decompresses image data into the supplied buffer.
-        /// </summary>
-        /// <param name="stream">The <see cref="Stream"/> to read image data from.</param>
-        /// <param name="byteCount">The number of bytes to read from the input stream.</param>
-        /// <param name="buffer">The output buffer for uncompressed data.</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Decompress(Stream stream, int byteCount, byte[] buffer)
+        public NoneTiffCompression(MemoryAllocator allocator)
+            : base(allocator)
+        {
+        }
+
+        /// <inheritdoc/>
+        public override void Decompress(Stream stream, int byteCount, Span<byte> buffer)
         {
             stream.ReadFull(buffer, byteCount);
         }

src/ImageSharp/Formats/Tiff/Compression/PackBitsTiffCompression.cs

@@ -4,69 +4,63 @@
 using System;
 using System.Buffers;
 using System.IO;
-using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using PackBits compression.
     /// </summary>
-    internal static class PackBitsTiffCompression
+    internal class PackBitsTiffCompression : TiffBaseCompression
     {
-        /// <summary>
-        /// Decompresses image data into the supplied buffer.
-        /// </summary>
-        /// <param name="stream">The <see cref="Stream"/> to read image data from.</param>
-        /// <param name="byteCount">The number of bytes to read from the input stream.</param>
-        /// <param name="buffer">The output buffer for uncompressed data.</param>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Decompress(Stream stream, int byteCount, byte[] buffer)
+        public PackBitsTiffCompression(MemoryAllocator allocator)
+            : base(allocator)
         {
-            byte[] compressedData = ArrayPool<byte>.Shared.Rent(byteCount);
+        }
+
+        /// <inheritdoc/>
+        public override void Decompress(Stream stream, int byteCount, Span<byte> buffer)
+        {
+            using IMemoryOwner<byte> compressedDataMemory = this.Allocator.Allocate<byte>(byteCount);
 
-            try
+            Span<byte> compressedData = compressedDataMemory.GetSpan();
+
+            stream.ReadFull(compressedData, byteCount);
+            int compressedOffset = 0;
+            int decompressedOffset = 0;
+
+            while (compressedOffset < byteCount)
             {
-                stream.ReadFull(compressedData, byteCount);
-                int compressedOffset = 0;
-                int decompressedOffset = 0;
+                byte headerByte = compressedData[compressedOffset];
 
-                while (compressedOffset < byteCount)
+                if (headerByte <= (byte)127)
                 {
-                    byte headerByte = compressedData[compressedOffset];
-
-                    if (headerByte <= (byte)127)
-                    {
-                        int literalOffset = compressedOffset + 1;
-                        int literalLength = compressedData[compressedOffset] + 1;
+                    int literalOffset = compressedOffset + 1;
+                    int literalLength = compressedData[compressedOffset] + 1;
 
-                        Array.Copy(compressedData, literalOffset, buffer, decompressedOffset, literalLength);
+                    compressedData.Slice(literalOffset, literalLength).CopyTo(buffer.Slice(decompressedOffset));
 
-                        compressedOffset += literalLength + 1;
-                        decompressedOffset += literalLength;
-                    }
-                    else if (headerByte == (byte)0x80)
-                    {
-                        compressedOffset += 1;
-                    }
-                    else
-                    {
-                        byte repeatData = compressedData[compressedOffset + 1];
-                        int repeatLength = 257 - headerByte;
+                    compressedOffset += literalLength + 1;
+                    decompressedOffset += literalLength;
+                }
+                else if (headerByte == (byte)0x80)
+                {
+                    compressedOffset += 1;
+                }
+                else
+                {
+                    byte repeatData = compressedData[compressedOffset + 1];
+                    int repeatLength = 257 - headerByte;
 
-                        ArrayCopyRepeat(repeatData, buffer, decompressedOffset, repeatLength);
+                    ArrayCopyRepeat(repeatData, buffer, decompressedOffset, repeatLength);
 
-                        compressedOffset += 2;
-                        decompressedOffset += repeatLength;
-                    }
+                    compressedOffset += 2;
+                    decompressedOffset += repeatLength;
                 }
             }
-            finally
-            {
-                ArrayPool<byte>.Shared.Return(compressedData);
-            }
         }
 
-        private static void ArrayCopyRepeat(byte value, byte[] destinationArray, int destinationIndex, int length)
+        private static void ArrayCopyRepeat(byte value, Span<byte> destinationArray, int destinationIndex, int length)
         {
             for (int i = 0; i < length; i++)
             {

src/ImageSharp/Formats/Tiff/Compression/TiffBaseCompression.cs

@@ -0,0 +1,29 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.IO;
+using SixLabors.ImageSharp.Memory;
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    /// <summary>
+    /// Base tiff decompressor class.
+    /// </summary>
+    internal abstract class TiffBaseCompression
+    {
+        private readonly MemoryAllocator allocator;
+
+        public TiffBaseCompression(MemoryAllocator allocator) => this.allocator = allocator;
+
+        protected MemoryAllocator Allocator => this.allocator;
+
+        /// <summary>
+        /// Decompresses image data into the supplied buffer.
+        /// </summary>
+        /// <param name="stream">The <see cref="Stream"/> to read image data from.</param>
+        /// <param name="byteCount">The number of bytes to read from the input stream.</param>
+        /// <param name="buffer">The output buffer for uncompressed data.</param>
+        public abstract void Decompress(Stream stream, int byteCount, Span<byte> buffer);
+    }
+}

src/ImageSharp/Formats/Tiff/Compression/TiffCompressionFactory.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Memory;
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    internal static class TiffCompressionFactory
+    {
+        public static TiffBaseCompression Create(TiffCompressionType compressionType, MemoryAllocator allocator)
+        {
+            switch (compressionType)
+            {
+                case TiffCompressionType.None:
+                    return new NoneTiffCompression(allocator);
+                case TiffCompressionType.PackBits:
+                    return new PackBitsTiffCompression(allocator);
+                case TiffCompressionType.Deflate:
+                    return new DeflateTiffCompression(allocator);
+                case TiffCompressionType.Lzw:
+                    return new LzwTiffCompression(allocator);
+                default:
+                    throw new InvalidOperationException();
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/Constants/TiffPredictor.cs

@@ -0,0 +1,26 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    /// <summary>
+    /// A mathematical operator that is applied to the image data before an encoding scheme is applied.
+    /// </summary>
+    public enum TiffPredictor : ushort
+    {
+        /// <summary>
+        /// No prediction scheme used before coding
+        /// </summary>
+        None = 1,
+
+        /// <summary>
+        /// Horizontal differencing.
+        /// </summary>
+        Horizontal = 2,
+
+        /// <summary>
+        /// Floating point horizontal differencing.
+        /// </summary>
+        FloatingPoint = 3
+    }
+}

src/ImageSharp/Formats/Tiff/Constants/TiffSampleFormat.cs

@@ -0,0 +1,41 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    /// <summary>
+    /// Specifies how to interpret each data sample in a pixel.
+    /// </summary>
+    public enum TiffSampleFormat : ushort
+    {
+        /// <summary>
+        /// Unsigned integer data. Default value.
+        /// </summary>
+        UnsignedInteger = 1,
+
+        /// <summary>
+        /// Signed integer data.
+        /// </summary>
+        SignedInteger = 2,
+
+        /// <summary>
+        /// IEEE floating point data.
+        /// </summary>
+        Float = 3,
+
+        /// <summary>
+        /// Undefined data format.
+        /// </summary>
+        Undefined = 4,
+
+        /// <summary>
+        /// The complex int.
+        /// </summary>
+        ComplexInt = 5,
+
+        /// <summary>
+        /// The complex float.
+        /// </summary>
+        ComplexFloat = 6
+    }
+}

src/ImageSharp/Formats/Tiff/Ifd/EntryReader.cs

@@ -105,6 +105,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                 case ExifTagValue.TileByteCounts:
                 case ExifTagValue.ColorMap:
                 case ExifTagValue.ExtraSamples:
+                case ExifTagValue.SampleFormat:
                     return true;
 
                 default:

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero1TiffColor.cs

@@ -11,28 +11,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// Implements the 'BlackIsZero' photometric interpretation (optimised for bilevel images).
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class BlackIsZero1TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class BlackIsZero1TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public BlackIsZero1TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
 
             for (int y = top; y < top + height; y++)
             {
@@ -45,6 +36,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                     {
                         int bit = (b >> (7 - shift)) & 1;
                         byte intensity = (bit == 1) ? (byte)255 : (byte)0;
+
                         color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
                         pixels[x + shift, y] = color;
                     }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero4TiffColor.cs

@@ -10,28 +10,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'BlackIsZero' photometric interpretation (optimised for 4-bit grayscale images).
     /// </summary>
-    internal class BlackIsZero4TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class BlackIsZero4TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public BlackIsZero4TiffColor()
-              : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
             bool isOddWidth = (width & 1) == 1;
 
             for (int y = top; y < top + height; y++)

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero8TiffColor.cs

@@ -10,34 +10,26 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'BlackIsZero' photometric interpretation (optimised for 8-bit grayscale images).
     /// </summary>
-    internal class BlackIsZero8TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class BlackIsZero8TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public BlackIsZero8TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
 
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = data[offset++];
+
                     color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
                     pixels[x, y] = color;
                 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZeroTiffColor.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'BlackIsZero' photometric interpretation (for all bit depths).
     /// </summary>
-    internal class BlackIsZeroTiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class BlackIsZeroTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly ushort bitsPerSample0;
@@ -19,26 +19,17 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         private readonly float factor;
 
         public BlackIsZeroTiffColor(ushort[] bitsPerSample)
-            : base(bitsPerSample, null)
         {
             this.bitsPerSample0 = bitsPerSample[0];
-            this.factor = (float)Math.Pow(2, this.bitsPerSample0) - 1.0f;
+            this.factor = (float)(1 << this.bitsPerSample0) - 1.0f;
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            BitReader bitReader = new BitReader(data);
+            var bitReader = new BitReader(data);
 
             for (int y = top; y < top + height; y++)
             {
@@ -46,6 +37,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                 {
                     int value = bitReader.ReadBits(this.bitsPerSample0);
                     float intensity = ((float)value) / this.factor;
+
                     color.FromVector4(new Vector4(intensity, intensity, intensity, 1.0f));
                     pixels[x, y] = color;
                 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/PaletteTiffColor.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Numerics;
-using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -12,33 +11,26 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'PaletteTiffColor' photometric interpretation (for all bit depths).
     /// </summary>
-    internal class PaletteTiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class PaletteTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly ushort bitsPerSample0;
 
         private readonly TPixel[] palette;
 
+        /// <param name="bitsPerSample">The number of bits per sample for each pixel.</param>
+        /// <param name="colorMap">The RGB color lookup table to use for decoding the image.</param>
         public PaletteTiffColor(ushort[] bitsPerSample, ushort[] colorMap)
-            : base(bitsPerSample, colorMap)
         {
             this.bitsPerSample0 = bitsPerSample[0];
-            int colorCount = (int)Math.Pow(2, this.bitsPerSample0);
+            int colorCount = 1 << this.bitsPerSample0;
             this.palette = GeneratePalette(colorMap, colorCount);
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            BitReader bitReader = new BitReader(data);
+            var bitReader = new BitReader(data);
 
             for (int y = top; y < top + height; y++)
             {
@@ -52,7 +44,6 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             }
         }
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static TPixel[] GeneratePalette(ushort[] colorMap, int colorCount)
         {
             var palette = new TPixel[colorCount];

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb888TiffColor.cs

@@ -10,38 +10,32 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'RGB' photometric interpretation (optimised for 8-bit full color images).
     /// </summary>
-    internal class Rgb888TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class Rgb888TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public Rgb888TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
+
                 for (int x = left; x < left + width; x++)
                 {
                     byte r = data[offset++];
                     byte g = data[offset++];
                     byte b = data[offset++];
+
                     color.FromRgba32(new Rgba32(r, g, b, 255));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
             }
         }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/RgbPlanarTiffColor.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
 using System.Numerics;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
@@ -20,11 +19,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
         private readonly float bFactor;
 
-        private readonly uint bitsPerSampleR;
+        private readonly ushort bitsPerSampleR;
 
-        private readonly uint bitsPerSampleG;
+        private readonly ushort bitsPerSampleG;
 
-        private readonly uint bitsPerSampleB;
+        private readonly ushort bitsPerSampleB;
 
         public RgbPlanarTiffColor(ushort[] bitsPerSample)
         /* : base(bitsPerSample, null) */
@@ -33,9 +32,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             this.bitsPerSampleG = bitsPerSample[1];
             this.bitsPerSampleB = bitsPerSample[2];
 
-            this.rFactor = (float)Math.Pow(2, this.bitsPerSampleR) - 1.0f;
-            this.gFactor = (float)Math.Pow(2, this.bitsPerSampleG) - 1.0f;
-            this.bFactor = (float)Math.Pow(2, this.bitsPerSampleB) - 1.0f;
+            this.rFactor = (float)(1 << this.bitsPerSampleR) - 1.0f;
+            this.gFactor = (float)(1 << this.bitsPerSampleG) - 1.0f;
+            this.bFactor = (float)(1 << this.bitsPerSampleB) - 1.0f;
         }
 
         /// <summary>
@@ -47,13 +46,13 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="top">The y-coordinate of the  top of the image block.</param>
         /// <param name="width">The width of the image block.</param>
         /// <param name="height">The height of the image block.</param>
-        public void Decode(byte[][] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        public void Decode(IManagedByteBuffer[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            var rBitReader = new BitReader(data[0]);
-            var gBitReader = new BitReader(data[1]);
-            var bBitReader = new BitReader(data[2]);
+            var rBitReader = new BitReader(data[0].GetSpan());
+            var gBitReader = new BitReader(data[1].GetSpan());
+            var bBitReader = new BitReader(data[2].GetSpan());
 
             for (int y = top; y < top + height; y++)
             {

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/RgbTiffColor.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'RGB' photometric interpretation (for all bit depths).
     /// </summary>
-    internal class RgbTiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class RgbTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly float rFactor;
@@ -20,38 +20,29 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
         private readonly float bFactor;
 
-        private readonly uint bitsPerSampleR;
+        private readonly ushort bitsPerSampleR;
 
-        private readonly uint bitsPerSampleG;
+        private readonly ushort bitsPerSampleG;
 
-        private readonly uint bitsPerSampleB;
+        private readonly ushort bitsPerSampleB;
 
         public RgbTiffColor(ushort[] bitsPerSample)
-          : base(bitsPerSample, null)
         {
             this.bitsPerSampleR = bitsPerSample[0];
             this.bitsPerSampleG = bitsPerSample[1];
             this.bitsPerSampleB = bitsPerSample[2];
 
-            this.rFactor = (float)Math.Pow(2, this.bitsPerSampleR) - 1.0f;
-            this.gFactor = (float)Math.Pow(2, this.bitsPerSampleG) - 1.0f;
-            this.bFactor = (float)Math.Pow(2, this.bitsPerSampleB) - 1.0f;
+            this.rFactor = (float)(1 << this.bitsPerSampleR) - 1.0f;
+            this.gFactor = (float)(1 << this.bitsPerSampleG) - 1.0f;
+            this.bFactor = (float)(1 << this.bitsPerSampleB) - 1.0f;
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            BitReader bitReader = new BitReader(data);
+            var bitReader = new BitReader(data);
 
             for (int y = top; y < top + height; y++)
             {

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffColorDecoder.cs → src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffBaseColorDecoder.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -10,22 +11,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// The base class for photometric interpretation decoders.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal abstract class TiffColorDecoder<TPixel>
+    internal abstract class TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        private readonly ushort[] bitsPerSample;
-
-        private readonly ushort[] colorMap;
-
-        /// <summary>
-        /// Initializes a new instance of the <see cref="TiffColorDecoder{TPixel}"/> class.
-        /// </summary>
-        /// <param name="bitsPerSample">The number of bits per sample for each pixel.</param>
-        /// <param name="colorMap">The RGB color lookup table to use for decoding the image.</param>
-        protected TiffColorDecoder(ushort[] bitsPerSample, ushort[] colorMap)
+        protected TiffBaseColorDecoder()
         {
-            this.bitsPerSample = bitsPerSample;
-            this.colorMap = colorMap;
         }
 
         /*
@@ -46,7 +36,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
         /// <param name="top">The y-coordinate of the  top of the image block.</param>
         /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public abstract void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height);
+        /// <param name="height">The height of the image block.</param>
+        public abstract void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height);
     }
 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffColorDecoderFactory.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     internal static class TiffColorDecoderFactory<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        public static TiffColorDecoder<TPixel> Create(TiffColorType colorType, ushort[] bitsPerSample, ushort[] colorMap)
+        public static TiffBaseColorDecoder<TPixel> Create(TiffColorType colorType, ushort[] bitsPerSample, ushort[] colorMap)
         {
             switch (colorType)
             {

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero1TiffColor.cs

@@ -10,28 +10,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'WhiteIsZero' photometric interpretation (optimised for bilevel images).
     /// </summary>
-    internal class WhiteIsZero1TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class WhiteIsZero1TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public WhiteIsZero1TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
 
             for (int y = top; y < top + height; y++)
             {
@@ -44,6 +35,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                     {
                         int bit = (b >> (7 - shift)) & 1;
                         byte intensity = (bit == 1) ? (byte)0 : (byte)255;
+
                         color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
                         pixels[x + shift, y] = color;
                     }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero4TiffColor.cs

@@ -10,28 +10,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'WhiteIsZero' photometric interpretation (optimised for 4-bit grayscale images).
     /// </summary>
-    internal class WhiteIsZero4TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class WhiteIsZero4TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public WhiteIsZero4TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
             bool isOddWidth = (width & 1) == 1;
 
             for (int y = top; y < top + height; y++)

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero8TiffColor.cs

@@ -10,34 +10,26 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'WhiteIsZero' photometric interpretation (optimised for 8-bit grayscale images).
     /// </summary>
-    internal class WhiteIsZero8TiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class WhiteIsZero8TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         public WhiteIsZero8TiffColor()
-            : base(null, null)
         {
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            uint offset = 0;
+            int offset = 0;
 
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = (byte)(255 - data[offset++]);
+
                     color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
                     pixels[x, y] = color;
                 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZeroTiffColor.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// <summary>
     /// Implements the 'WhiteIsZero' photometric interpretation (for all bit depths).
     /// </summary>
-    internal class WhiteIsZeroTiffColor<TPixel> : TiffColorDecoder<TPixel>
+    internal class WhiteIsZeroTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly ushort bitsPerSample0;
@@ -19,26 +19,17 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         private readonly float factor;
 
         public WhiteIsZeroTiffColor(ushort[] bitsPerSample)
-            : base(bitsPerSample, null)
         {
             this.bitsPerSample0 = bitsPerSample[0];
             this.factor = (float)Math.Pow(2, this.bitsPerSample0) - 1.0f;
         }
 
-        /// <summary>
-        /// Decodes pixel data using the current photometric interpretation.
-        /// </summary>
-        /// <param name="data">The buffer to read image data from.</param>
-        /// <param name="pixels">The image buffer to write pixels to.</param>
-        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
-        /// <param name="top">The y-coordinate of the  top of the image block.</param>
-        /// <param name="width">The width of the image block.</param>
-        /// <param name="height">The height of the image block.</param>
-        public override void Decode(byte[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
-            TPixel color = default(TPixel);
+            var color = default(TPixel);
 
-            BitReader bitReader = new BitReader(data);
+            var bitReader = new BitReader(data);
 
             for (int y = top; y < top + height; y++)
             {

src/ImageSharp/Formats/Tiff/Streams/TiffStreamFactory.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -11,12 +11,6 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// </summary>
     internal static class TiffStreamFactory
     {
-        public static TiffStream CreateBySignature(Stream stream)
-        {
-            TiffByteOrder order = ReadByteOrder(stream);
-            return Create(order, stream);
-        }
-
         /// <summary>
         /// Creates the specified byte order.
         /// </summary>
@@ -40,7 +34,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// Reads the byte order of stream.
         /// </summary>
         /// <param name="stream">The stream.</param>
-        private static TiffByteOrder ReadByteOrder(Stream stream)
+        public static TiffByteOrder ReadByteOrder(Stream stream)
         {
             byte[] headerBytes = new byte[2];
             stream.Read(headerBytes, 0, 2);

src/ImageSharp/Formats/Tiff/TiffDecoder.cs

@@ -4,6 +4,7 @@
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
+using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
@@ -24,10 +25,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         {
             Guard.NotNull(stream, "stream");
 
-            using (var decoder = new TiffDecoderCore(stream, configuration, this))
-            {
-                return decoder.Decode<TPixel>();
-            }
+            using var decoder = new TiffDecoderCore(stream, configuration, this);
+            return decoder.Decode<TPixel>(configuration, stream);
         }
 
         /// <inheritdoc/>
@@ -37,25 +36,33 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         public Task<Image<TPixel>> DecodeAsync<TPixel>(Configuration configuration, Stream stream, CancellationToken cancellationToken)
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            throw new System.NotImplementedException();
+            Guard.NotNull(stream, nameof(stream));
+
+            var decoder = new TiffDecoderCore(stream, configuration, this);
+            return decoder.DecodeAsync<TPixel>(configuration, stream, cancellationToken);
         }
 
         /// <inheritdoc/>
-        public Task<Image> DecodeAsync(Configuration configuration, Stream stream, CancellationToken cancellationToken)
-        {
-            throw new System.NotImplementedException();
-        }
+        public async Task<Image> DecodeAsync(Configuration configuration, Stream stream, CancellationToken cancellationToken)
+          => await this.DecodeAsync<Rgba32>(configuration, stream, cancellationToken)
+            .ConfigureAwait(false);
 
         /// <inheritdoc/>
         public IImageInfo Identify(Configuration configuration, Stream stream)
         {
-            throw new System.NotImplementedException();
+            Guard.NotNull(stream, nameof(stream));
+
+            var decoder = new TiffDecoderCore(stream, configuration, this);
+            return decoder.Identify(configuration, stream);
         }
 
         /// <inheritdoc/>
         public Task<IImageInfo> IdentifyAsync(Configuration configuration, Stream stream, CancellationToken cancellationToken)
         {
-            throw new System.NotImplementedException();
+            Guard.NotNull(stream, nameof(stream));
+
+            var decoder = new TiffDecoderCore(stream, configuration, this);
+            return decoder.IdentifyAsync(configuration, stream, cancellationToken);
         }
     }
 }

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -25,6 +25,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         private readonly Configuration configuration;
 
+        /// <summary>
+        /// Used for allocating memory during processing operations.
+        /// </summary>
+        private readonly MemoryAllocator memoryAllocator;
+
         /// <summary>
         /// Gets or sets a value indicating whether the metadata should be ignored when the image is being decoded.
         /// </summary>
@@ -41,6 +46,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
             this.configuration = configuration ?? Configuration.Default;
             this.ignoreMetadata = options.IgnoreMetadata;
+            this.memoryAllocator = this.configuration.MemoryAllocator;
         }
 
         /// <summary>
@@ -52,26 +58,18 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         public TiffDecoderCore(Stream stream, Configuration configuration, ITiffDecoderOptions options)
             : this(configuration, options)
         {
-            this.Stream = TiffStreamFactory.CreateBySignature(stream);
+            this.ByteOrder = TiffStreamFactory.ReadByteOrder(stream);
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="TiffDecoderCore" /> class.
+        /// Gets the byte order.
         /// </summary>
-        /// <param name="byteOrder">The byte order.</param>
-        /// <param name="stream">The input stream.</param>
-        /// <param name="configuration">The configuration.</param>
-        /// <param name="options">The decoder options.</param>
-        public TiffDecoderCore(TiffByteOrder byteOrder, Stream stream, Configuration configuration, ITiffDecoderOptions options)
-            : this(configuration, options)
-        {
-            this.Stream = TiffStreamFactory.Create(byteOrder, stream);
-        }
+        public TiffByteOrder ByteOrder { get; }
 
         /// <summary>
         /// Gets the input stream.
         /// </summary>
-        public TiffStream Stream { get; }
+        public TiffStream Stream { get; private set; }
 
         /// <summary>
         /// Gets or sets the number of bits for each sample of the pixel format used to encode the image.
@@ -109,32 +107,31 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <inheritdoc/>
         public Size Dimensions { get; private set; }
 
-        /// <summary>
-        /// Decodes the image from the specified <see cref="Stream"/>  and sets
-        /// the data to image.
-        /// </summary>
-        /// <typeparam name="TPixel">The pixel format.</typeparam>
-        /// <returns>The decoded image.</returns>
-        public Image<TPixel> Decode<TPixel>()
+        /// <inheritdoc/>
+        public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
             where TPixel : unmanaged, IPixel<TPixel>
         {
+            this.Stream = TiffStreamFactory.Create(this.ByteOrder, stream);
             var reader = new DirectoryReader(this.Stream);
+
             IEnumerable<IExifValue[]> directories = reader.Read();
 
             var frames = new List<ImageFrame<TPixel>>();
+            var framesMetadata = new List<TiffFrameMetadata>();
             foreach (IExifValue[] ifd in directories)
             {
-                ImageFrame<TPixel> frame = this.DecodeFrame<TPixel>(ifd);
+                ImageFrame<TPixel> frame = this.DecodeFrame<TPixel>(ifd, out TiffFrameMetadata frameMetadata);
                 frames.Add(frame);
+                framesMetadata.Add(frameMetadata);
             }
 
-            ImageMetadata metadata = frames.CreateMetadata(this.ignoreMetadata, this.Stream.ByteOrder);
+            ImageMetadata metadata = framesMetadata.CreateMetadata(this.ignoreMetadata, this.Stream.ByteOrder);
 
             // todo: tiff frames can have different sizes
             {
-                var root = frames.First();
+                ImageFrame<TPixel> root = frames.First();
                 this.Dimensions = root.Size();
-                foreach (var frame in frames)
+                foreach (ImageFrame<TPixel> frame in frames)
                 {
                     if (frame.Size() != root.Size())
                     {
@@ -148,9 +145,33 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             return image;
         }
 
-        /// <summary>
-        /// Dispose
-        /// </summary>
+        /// <inheritdoc/>
+        public IImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
+        {
+            this.Stream = TiffStreamFactory.Create(this.ByteOrder, stream);
+            var reader = new DirectoryReader(this.Stream);
+
+            IEnumerable<IExifValue[]> directories = reader.Read();
+
+            var framesMetadata = new List<TiffFrameMetadata>();
+            foreach (IExifValue[] ifd in directories)
+            {
+                framesMetadata.Add(new TiffFrameMetadata() { Tags = ifd });
+            }
+
+            ImageMetadata metadata = framesMetadata.CreateMetadata(this.ignoreMetadata, this.Stream.ByteOrder);
+
+            TiffFrameMetadata root = framesMetadata.First();
+            int bitsPerPixel = 0;
+            foreach (var bits in root.BitsPerSample)
+            {
+                bitsPerPixel += bits;
+            }
+
+            return new ImageInfo(new PixelTypeInfo(bitsPerPixel), (int)root.Width, (int)root.Height, metadata);
+        }
+
+        /// <inheritdoc/>
         public void Dispose()
         {
             // nothing
@@ -161,11 +182,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="tags">The IFD tags.</param>
-        private ImageFrame<TPixel> DecodeFrame<TPixel>(IExifValue[] tags)
+        /// <param name="metadata">The frame metadata.</param>
+        /// <returns>
+        /// The tiff frame.
+        /// </returns>
+        private ImageFrame<TPixel> DecodeFrame<TPixel>(IExifValue[] tags, out TiffFrameMetadata metadata)
             where TPixel : unmanaged, IPixel<TPixel>
         {
             var coreMetadata = new ImageFrameMetadata();
-            TiffFrameMetadata metadata = coreMetadata.GetTiffMetadata();
+            metadata = coreMetadata.GetTiffMetadata();
             metadata.Tags = tags;
 
             this.VerifyAndParseOptions(metadata);
@@ -178,7 +203,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             uint[] stripOffsets = metadata.StripOffsets;
             uint[] stripByteCounts = metadata.StripByteCounts;
 
-            this.DecodeImageStrips(frame, rowsPerStrip, stripOffsets, stripByteCounts);
+            if (this.PlanarConfiguration == TiffPlanarConfiguration.Planar)
+            {
+                this.DecodeStripsPlanar(frame, rowsPerStrip, stripOffsets, stripByteCounts);
+            }
+            else
+            {
+                this.DecodeStripsChunky(frame, rowsPerStrip, stripOffsets, stripByteCounts);
+            }
 
             return frame;
         }
@@ -190,12 +222,13 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="height">The height for the desired pixel buffer.</param>
         /// <param name="plane">The index of the plane for planar image configuration (or zero for chunky).</param>
         /// <returns>The size (in bytes) of the required pixel buffer.</returns>
-        private int CalculateImageBufferSize(int width, int height, int plane)
+        private int CalculateStripBufferSize(int width, int height, int plane = -1)
         {
             uint bitsPerPixel = 0;
 
             if (this.PlanarConfiguration == TiffPlanarConfiguration.Chunky)
             {
+                DebugGuard.IsTrue(plane == -1, "Excepted Chunky planar.");
                 for (int i = 0; i < this.BitsPerSample.Length; i++)
                 {
                     bitsPerPixel += this.BitsPerSample[i];
@@ -207,7 +240,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             }
 
             int bytesPerRow = ((width * (int)bitsPerPixel) + 7) / 8;
-            return bytesPerRow * height;
+            int stripBytes = bytesPerRow * height;
+
+            return stripBytes;
         }
 
         /// <summary>
@@ -218,35 +253,28 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="rowsPerStrip">The number of rows per strip of data.</param>
         /// <param name="stripOffsets">An array of byte offsets to each strip in the image.</param>
         /// <param name="stripByteCounts">An array of the size of each strip (in bytes).</param>
-        private void DecodeImageStrips<TPixel>(ImageFrame<TPixel> frame, int rowsPerStrip, uint[] stripOffsets, uint[] stripByteCounts)
+        private void DecodeStripsPlanar<TPixel>(ImageFrame<TPixel> frame, int rowsPerStrip, uint[] stripOffsets, uint[] stripByteCounts)
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            int stripsPerPixel = this.PlanarConfiguration == TiffPlanarConfiguration.Chunky ? 1 : this.BitsPerSample.Length;
+            int stripsPerPixel = this.BitsPerSample.Length;
             int stripsPerPlane = stripOffsets.Length / stripsPerPixel;
 
             Buffer2D<TPixel> pixels = frame.PixelBuffer;
 
-            byte[][] stripBytes = new byte[stripsPerPixel][];
-
-            for (int stripIndex = 0; stripIndex < stripBytes.Length; stripIndex++)
-            {
-                int uncompressedStripSize = this.CalculateImageBufferSize(frame.Width, rowsPerStrip, stripIndex);
-                stripBytes[stripIndex] = ArrayPool<byte>.Shared.Rent(uncompressedStripSize);
-            }
+            var stripBuffers = new IManagedByteBuffer[stripsPerPixel];
 
             try
             {
-                TiffColorDecoder<TPixel> chunkyDecoder = null;
-                RgbPlanarTiffColor<TPixel> planarDecoder = null;
-                if (this.PlanarConfiguration == TiffPlanarConfiguration.Chunky)
-                {
-                    chunkyDecoder = TiffColorDecoderFactory<TPixel>.Create(this.ColorType, this.BitsPerSample, this.ColorMap);
-                }
-                else
+                for (int stripIndex = 0; stripIndex < stripBuffers.Length; stripIndex++)
                 {
-                    planarDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(this.ColorType, this.BitsPerSample, this.ColorMap);
+                    int uncompressedStripSize = this.CalculateStripBufferSize(frame.Width, rowsPerStrip, stripIndex);
+                    stripBuffers[stripIndex] = this.memoryAllocator.AllocateManagedByteBuffer(uncompressedStripSize);
                 }
 
+                TiffBaseCompression decompressor = TiffCompressionFactory.Create(this.CompressionType, this.memoryAllocator);
+
+                RgbPlanarTiffColor<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(this.ColorType, this.BitsPerSample, this.ColorMap);
+
                 for (int i = 0; i < stripsPerPlane; i++)
                 {
                     int stripHeight = i < stripsPerPlane - 1 || frame.Height % rowsPerStrip == 0 ? rowsPerStrip : frame.Height % rowsPerStrip;
@@ -254,37 +282,45 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                     for (int planeIndex = 0; planeIndex < stripsPerPixel; planeIndex++)
                     {
                         int stripIndex = (i * stripsPerPixel) + planeIndex;
-                        CompressionFactory.DecompressImageBlock(this.Stream.InputStream, this.CompressionType, stripOffsets[stripIndex], stripByteCounts[stripIndex], stripBytes[planeIndex]);
-                    }
 
-                    if (this.PlanarConfiguration == TiffPlanarConfiguration.Chunky)
-                    {
-                        chunkyDecoder.Decode(stripBytes[0], pixels, 0, rowsPerStrip * i, frame.Width, stripHeight);
-                    }
-                    else
-                    {
-                        planarDecoder.Decode(stripBytes, pixels, 0, rowsPerStrip * i, frame.Width, stripHeight);
+                        this.Stream.Seek(stripOffsets[stripIndex]);
+                        decompressor.Decompress(this.Stream.InputStream, (int)stripByteCounts[stripIndex], stripBuffers[planeIndex].GetSpan());
                     }
+
+                    colorDecoder.Decode(stripBuffers, pixels, 0, rowsPerStrip * i, frame.Width, stripHeight);
                 }
             }
             finally
             {
-                for (int stripIndex = 0; stripIndex < stripBytes.Length; stripIndex++)
+                foreach (IManagedByteBuffer buf in stripBuffers)
                 {
-                    ArrayPool<byte>.Shared.Return(stripBytes[stripIndex]);
+                    buf?.Dispose();
                 }
             }
         }
 
-        public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
-            where TPixel : unmanaged, IPixel<TPixel>
+        private void DecodeStripsChunky<TPixel>(ImageFrame<TPixel> frame, int rowsPerStrip, uint[] stripOffsets, uint[] stripByteCounts)
+           where TPixel : unmanaged, IPixel<TPixel>
         {
-            throw new NotImplementedException();
-        }
+            int uncompressedStripSize = this.CalculateStripBufferSize(frame.Width, rowsPerStrip);
 
-        public IImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
-        {
-            throw new NotImplementedException();
+            using IManagedByteBuffer stripBuffer = this.memoryAllocator.AllocateManagedByteBuffer(uncompressedStripSize);
+
+            Buffer2D<TPixel> pixels = frame.PixelBuffer;
+
+            TiffBaseCompression decompressor = TiffCompressionFactory.Create(this.CompressionType, this.memoryAllocator);
+
+            TiffBaseColorDecoder<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.Create(this.ColorType, this.BitsPerSample, this.ColorMap);
+
+            for (int stripIndex = 0; stripIndex < stripOffsets.Length; stripIndex++)
+            {
+                int stripHeight = stripIndex < stripOffsets.Length - 1 || frame.Height % rowsPerStrip == 0 ? rowsPerStrip : frame.Height % rowsPerStrip;
+
+                this.Stream.Seek(stripOffsets[stripIndex]);
+                decompressor.Decompress(this.Stream.InputStream, (int)stripByteCounts[stripIndex], stripBuffer.GetSpan());
+
+                colorDecoder.Decode(stripBuffer.GetSpan(), pixels, 0, rowsPerStrip * stripIndex, frame.Width, stripHeight);
+            }
         }
     }
 }

src/ImageSharp/Formats/Tiff/TiffDecoderHelpers.cs

@@ -2,11 +2,8 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
-using System.Net.Http.Headers;
-using SixLabors.ImageSharp.Formats.Tiff;
 using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
 using SixLabors.ImageSharp.Metadata.Profiles.Icc;
@@ -20,14 +17,13 @@ namespace SixLabors.ImageSharp.Formats.Tiff
     /// </summary>
     internal static class TiffDecoderHelpers
     {
-        public static ImageMetadata CreateMetadata<TPixel>(this IList<ImageFrame<TPixel>> frames, bool ignoreMetadata, TiffByteOrder byteOrder)
-            where TPixel : unmanaged, IPixel<TPixel>
+        public static ImageMetadata CreateMetadata(this IList<TiffFrameMetadata> frames, bool ignoreMetadata, TiffByteOrder byteOrder)
         {
             var coreMetadata = new ImageMetadata();
             TiffMetadata tiffMetadata = coreMetadata.GetTiffMetadata();
             tiffMetadata.ByteOrder = byteOrder;
 
-            TiffFrameMetadata rootFrameMetadata = frames.First().Metadata.GetTiffMetadata();
+            TiffFrameMetadata rootFrameMetadata = frames.First();
             switch (rootFrameMetadata.ResolutionUnit)
             {
                 case TiffResolutionUnit.None:
@@ -53,13 +49,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
             if (!ignoreMetadata)
             {
-                foreach (ImageFrame<TPixel> frame in frames)
+                foreach (TiffFrameMetadata frame in frames)
                 {
-                    TiffFrameMetadata frameMetadata = frame.Metadata.GetTiffMetadata();
-
                     if (tiffMetadata.XmpProfile == null)
                     {
-                        byte[] buf = frameMetadata.GetArrayValue<byte>(ExifTag.XMP, true);
+                        byte[] buf = frame.GetArray<byte>(ExifTag.XMP, true);
                         if (buf != null)
                         {
                             tiffMetadata.XmpProfile = buf;
@@ -68,7 +62,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
                     if (coreMetadata.IptcProfile == null)
                     {
-                        byte[] buf = frameMetadata.GetArrayValue<byte>(ExifTag.IPTC, true);
+                        byte[] buf = frame.GetArray<byte>(ExifTag.IPTC, true);
                         if (buf != null)
                         {
                             coreMetadata.IptcProfile = new IptcProfile(buf);
@@ -77,7 +71,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
                     if (coreMetadata.IccProfile == null)
                     {
-                        byte[] buf = frameMetadata.GetArrayValue<byte>(ExifTag.IccProfile, true);
+                        byte[] buf = frame.GetArray<byte>(ExifTag.IccProfile, true);
                         if (buf != null)
                         {
                             coreMetadata.IccProfile = new IccProfile(buf);
@@ -106,11 +100,27 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                 throw new NotSupportedException("The lower-order bits of the byte FillOrder is not supported.");
             }
 
-            if (entries.GetArrayValue<uint>(ExifTag.TileOffsets, true) != null)
+            if (entries.GetArray<uint>(ExifTag.TileOffsets, true) != null)
             {
                 throw new NotSupportedException("The Tile images is not supported.");
             }
 
+            if (entries.Predictor != TiffPredictor.None)
+            {
+                throw new NotSupportedException("At the moment support only None Predictor.");
+            }
+
+            if (entries.SampleFormat != null)
+            {
+                foreach (TiffSampleFormat format in entries.SampleFormat)
+                {
+                    if (format != TiffSampleFormat.UnsignedInteger)
+                    {
+                        throw new NotSupportedException("At the moment support only UnsignedInteger SampleFormat.");
+                    }
+                }
+            }
+
             ParseCompression(options, entries.Compression);
 
             options.PlanarConfiguration = entries.PlanarConfiguration;

src/ImageSharp/Formats/Tiff/TiffFrameMetadata.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
@@ -16,6 +17,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
         private const TiffPlanarConfiguration DefaultPlanarConfiguration = TiffPlanarConfiguration.Chunky;
 
+        private const TiffPredictor DefaultPredictor = TiffPredictor.None;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="TiffFrameMetadata"/> class.
         /// </summary>
@@ -39,17 +42,17 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <summary>
         /// Gets the number of columns in the image, i.e., the number of pixels per row.
         /// </summary>
-        public uint Width => this.GetSingleUInt(ExifTag.ImageWidth);
+        public uint Width => this.GetSingle<uint>(ExifTag.ImageWidth);
 
         /// <summary>
         /// Gets the number of rows of pixels in the image.
         /// </summary>
-        public uint Height => this.GetSingleUInt(ExifTag.ImageLength);
+        public uint Height => this.GetSingle<uint>(ExifTag.ImageLength);
 
         /// <summary>
         /// Gets the number of bits per component.
         /// </summary>
-        public ushort[] BitsPerSample => this.GetArrayValue<ushort>(ExifTag.BitsPerSample, true);
+        public ushort[] BitsPerSample => this.GetArray<ushort>(ExifTag.BitsPerSample, true);
 
         /// <summary>Gets the compression scheme used on the image data.</summary>
         /// <value>The compression scheme used on the image data.</value>
@@ -81,17 +84,22 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         public string Model => this.GetString(ExifTag.Model);
 
         /// <summary>Gets for each strip, the byte offset of that strip..</summary>
-        public uint[] StripOffsets => this.GetArrayValue<uint>(ExifTag.StripOffsets);
+        public uint[] StripOffsets => this.GetArray<uint>(ExifTag.StripOffsets);
+
+        /// <summary>
+        /// Gets the number of components per pixel.
+        /// </summary>
+        public ushort SamplesPerPixel => this.GetSingle<ushort>(ExifTag.SamplesPerPixel);
 
         /// <summary>
         /// Gets the number of rows per strip.
         /// </summary>
-        public uint RowsPerStrip => this.GetSingleUInt(ExifTag.RowsPerStrip);
+        public uint RowsPerStrip => this.GetSingle<uint>(ExifTag.RowsPerStrip);
 
         /// <summary>
         /// Gets for each strip, the number of bytes in the strip after compression.
         /// </summary>
-        public uint[] StripByteCounts => this.GetArrayValue<uint>(ExifTag.StripByteCounts);
+        public uint[] StripByteCounts => this.GetArray<uint>(ExifTag.StripByteCounts);
 
         /// <summary>Gets the resolution of the image in x- direction.</summary>
         /// <value>The density of the image in x- direction.</value>
@@ -168,22 +176,33 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <summary>
         /// Gets a color map for palette color images.
         /// </summary>
-        public ushort[] ColorMap => this.GetArrayValue<ushort>(ExifTag.ColorMap, true);
+        public ushort[] ColorMap => this.GetArray<ushort>(ExifTag.ColorMap, true);
 
         /// <summary>
         /// Gets the description of extra components.
         /// </summary>
-        public ushort[] ExtraSamples => this.GetArrayValue<ushort>(ExifTag.ExtraSamples, true);
+        public ushort[] ExtraSamples => this.GetArray<ushort>(ExifTag.ExtraSamples, true);
 
         /// <summary>
         /// Gets the copyright notice.
         /// </summary>
         public string Copyright => this.GetString(ExifTag.Copyright);
 
-        internal T[] GetArrayValue<T>(ExifTag tag, bool optional = false)
+        /// <summary>
+        /// Gets a mathematical operator that is applied to the image data before an encoding scheme is applied.
+        /// </summary>
+        public TiffPredictor Predictor => this.GetSingleEnum<TiffPredictor, ushort>(ExifTag.Predictor, DefaultPredictor);
+
+        /// <summary>
+        /// Gets the specifies how to interpret each data sample in a pixel.
+        /// <see cref="SamplesPerPixel"/>
+        /// </summary>
+        public TiffSampleFormat[] SampleFormat => this.GetEnumArray<TiffSampleFormat, ushort>(ExifTag.SampleFormat, true);
+
+        internal T[] GetArray<T>(ExifTag tag, bool optional = false)
             where T : struct
         {
-            if (this.TryGetArrayValue(tag, out T[] result))
+            if (this.TryGetArray(tag, out T[] result))
             {
                 return result;
             }
@@ -196,7 +215,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             return null;
         }
 
-        private bool TryGetArrayValue<T>(ExifTag tag, out T[] result)
+        private bool TryGetArray<T>(ExifTag tag, out T[] result)
             where T : struct
         {
             foreach (IExifValue entry in this.Tags)
@@ -214,6 +233,24 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             return false;
         }
 
+        private TEnum[] GetEnumArray<TEnum, TTagValue>(ExifTag tag, bool optional = false)
+          where TEnum : struct
+          where TTagValue : struct
+        {
+            if (this.TryGetArray(tag, out TTagValue[] result))
+            {
+                // todo: improve
+                return result.Select(a => (TEnum)(object)a).ToArray();
+            }
+
+            if (!optional)
+            {
+                throw new ArgumentException("Required tag is not founded: " + tag, nameof(tag));
+            }
+
+            return null;
+        }
+
         private string GetString(ExifTag tag)
         {
             foreach (IExifValue entry in this.Tags)
@@ -246,42 +283,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         private TEnum GetSingleEnum<TEnum, TTagValue>(ExifTag tag, TEnum? defaultValue = null)
             where TEnum : struct
             where TTagValue : struct
-        {
-            if (!this.TryGetSingle(tag, out TTagValue value))
-            {
-                if (defaultValue != null)
-                {
-                    return defaultValue.Value;
-                }
-
-                throw new ArgumentException("Required tag is not founded: " + tag, nameof(tag));
-            }
-
-            return (TEnum)(object)value;
-        }
+        => this.GetSingleEnumNullable<TEnum, TTagValue>(tag) ?? (defaultValue != null ? defaultValue.Value : throw new ArgumentException("Required tag is not founded: " + tag, nameof(tag)));
 
-        /*
-        private TEnum GetSingleEnum<TEnum, TEnumParent, TTagValue>(ExifTag tag, TEnum? defaultValue = null)
-       where TEnum : struct
-       where TEnumParent : struct
-       where TTagValue : struct
-        {
-            if (!this.TryGetSingle(tag, out TTagValue value))
-            {
-                if (defaultValue != null)
-                {
-                    return defaultValue.Value;
-                }
-
-                throw new ArgumentException("Required tag is not founded: " + tag, nameof(tag));
-            }
-
-            return (TEnum)(object)(TEnumParent)Convert.ChangeType(value, typeof(TEnumParent));
-        } */
-
-        private uint GetSingleUInt(ExifTag tag)
+        private T GetSingle<T>(ExifTag tag)
+            where T : struct
         {
-            if (this.TryGetSingle(tag, out uint result))
+            if (this.TryGetSingle(tag, out T result))
             {
                 return result;
             }
@@ -290,7 +297,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         }
 
         private bool TryGetSingle<T>(ExifTag tag, out T result)
-         where T : struct
+            where T : struct
         {
             foreach (IExifValue entry in this.Tags)
             {

src/ImageSharp/Formats/Tiff/Utils/BitReader.cs

@@ -1,24 +1,28 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
+
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
     /// <summary>
     /// Utility class to read a sequence of bits from an array
     /// </summary>
-    internal class BitReader
+    internal ref struct BitReader
     {
-        private readonly byte[] array;
+        private readonly ReadOnlySpan<byte> array;
         private int offset;
         private int bitOffset;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="BitReader" /> class.
+        /// Initializes a new instance of the <see cref="BitReader" /> struct.
         /// </summary>
         /// <param name="array">The array to read data from.</param>
-        public BitReader(byte[] array)
+        public BitReader(ReadOnlySpan<byte> array)
         {
             this.array = array;
+            this.offset = 0;
+            this.bitOffset = 0;
         }
 
         /// <summary>
@@ -59,4 +63,4 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             }
         }
     }
-}
+}

src/ImageSharp/Formats/Tiff/Utils/TiffLzwDecoder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -91,7 +91,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="length">The length of the compressed data.</param>
         /// <param name="dataSize">Size of the data.</param>
         /// <param name="pixels">The pixel array to decode to.</param>
-        public void DecodePixels(int length, int dataSize, byte[] pixels)
+        public void DecodePixels(int length, int dataSize, Span<byte> pixels)
         {
             Guard.MustBeLessThan(dataSize, int.MaxValue, nameof(dataSize));
 
@@ -268,4 +268,4 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             this.isDisposed = true;
         }
     }
-}
+}

src/ImageSharp/Formats/Tiff/Utils/TiffUtils.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.IO;
 
 namespace SixLabors.ImageSharp.Formats.Tiff
@@ -16,7 +17,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <param name="stream">The stream to read from.</param>
         /// <param name="buffer">A buffer to store the retrieved data.</param>
         /// <param name="count">The number of bytes to read.</param>
-        public static void ReadFull(this Stream stream, byte[] buffer, int count)
+        public static void ReadFull(this Stream stream, Span<byte> buffer, int count)
         {
             int offset = 0;
 
@@ -39,9 +40,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         /// <param name="stream">The stream to read from.</param>
         /// <param name="buffer">A buffer to store the retrieved data.</param>
-        public static void ReadFull(this Stream stream, byte[] buffer)
+        public static void ReadFull(this Stream stream, Span<byte> buffer)
         {
             ReadFull(stream, buffer, buffer.Length);
         }
     }
-}
+}

src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.LongArray.cs

@@ -59,7 +59,6 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
         /// <summary>
         /// Gets the StripByteCounts exif tag.
         /// </summary>
-        /// </value>
         public static ExifTag<uint[]> StripByteCounts { get; } = new ExifTag<uint[]>(ExifTagValue.StripByteCounts);
 
         /// <summary>

tests/ImageSharp.Benchmarks/Codecs/DecodeTiff.cs

@@ -17,7 +17,7 @@ namespace SixLabors.ImageSharp.Benchmarks.Codecs
 
         private string TestImageFullPath => Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, this.TestImage);
 
-        [Params(TestImages.Tiff.RgbLzw)]
+        [Params(TestImages.Tiff.RgbPackbits)]
         public string TestImage { get; set; }
 
         [GlobalSetup]

tests/ImageSharp.Tests/FileTestBase.cs

@@ -24,7 +24,7 @@ namespace SixLabors.ImageSharp.Tests
                 TestImages.Png.Splash,
                 TestImages.Gif.Trans,
                 TestImages.Tga.Bit24PalRleTopRight,
-                TestImages.Tiff.RgbLzw,
+                TestImages.Tiff.RgbPackbits,
             };
 
         /// <summary>
@@ -116,7 +116,7 @@ namespace SixLabors.ImageSharp.Tests
             // TestFile.Create(TestImages.Gif.Cheers), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Gif.Giphy) // Perf: Enable for local testing only
             TestFile.Create(TestImages.Tga.Bit24PalRleTopRight),
-            TestFile.Create(TestImages.Tiff.RgbLzw),
+            TestFile.Create(TestImages.Tiff.RgbPackbits),
         };
 #pragma warning restore SA1515 // Single-line comment should be preceded by blank line
     }

tests/ImageSharp.Tests/Formats/Tiff/Compression/DeflateTiffCompressionTests.cs

@@ -4,6 +4,7 @@
 using System.IO;
 using SixLabors.ImageSharp.Formats.Png.Zlib;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Memory;
 using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
@@ -23,7 +24,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             {
                 byte[] buffer = new byte[data.Length];
 
-                DeflateTiffCompression.Decompress(stream, (int)stream.Length, buffer);
+                new DeflateTiffCompression(null).Decompress(stream, (int)stream.Length, buffer);
 
                 Assert.Equal(data, buffer);
             }

tests/ImageSharp.Tests/Formats/Tiff/Compression/LzwTiffCompressionTests.cs

@@ -22,7 +22,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             {
                 byte[] buffer = new byte[data.Length];
 
-                LzwTiffCompression.Decompress(stream, (int)stream.Length, buffer);
+                new LzwTiffCompression(null).Decompress(stream, (int)stream.Length, buffer);
 
                 Assert.Equal(data, buffer);
             }

tests/ImageSharp.Tests/Formats/Tiff/Compression/NoneTiffCompressionTests.cs

@@ -18,7 +18,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             Stream stream = new MemoryStream(inputData);
             byte[] buffer = new byte[expectedResult.Length];
 
-            NoneTiffCompression.Decompress(stream, byteCount, buffer);
+            new NoneTiffCompression(null).Decompress(stream, byteCount, buffer);
 
             Assert.Equal(expectedResult, buffer);
         }

tests/ImageSharp.Tests/Formats/Tiff/Compression/PackBitsTiffCompressionTests.cs

@@ -3,6 +3,7 @@
 
 using System.IO;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Memory;
 using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff.Formats.Tiff
@@ -25,7 +26,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff.Formats.Tiff
             Stream stream = new MemoryStream(inputData);
             byte[] buffer = new byte[expectedResult.Length];
 
-            PackBitsTiffCompression.Decompress(stream, inputData.Length, buffer);
+            new PackBitsTiffCompression(new ArrayPoolMemoryAllocator()).Decompress(stream, inputData.Length, buffer);
 
             Assert.Equal(expectedResult, buffer);
         }

tests/ImageSharp.Tests/Formats/Tiff/PhotometricInterpretation/RgbPlanarTiffColorTests.cs

@@ -1,8 +1,10 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Collections.Generic;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using Xunit;
 
@@ -190,7 +192,14 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
         {
             AssertDecode(expectedResult, pixels =>
                 {
-                    new RgbPlanarTiffColor<Rgba32>(bitsPerSample).Decode(inputData, pixels, left, top, width, height);
+                    var buffers = new IManagedByteBuffer[inputData.Length];
+                    for (int i = 0; i < buffers.Length; i++)
+                    {
+                        buffers[i] = Configuration.Default.MemoryAllocator.AllocateManagedByteBuffer(inputData[i].Length);
+                        ((Span<byte>)inputData[i]).CopyTo(buffers[i].GetSpan());
+                    }
+
+                    new RgbPlanarTiffColor<Rgba32>(bitsPerSample).Decode(buffers, pixels, left, top, width, height);
                 });
         }
     }

tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs

@@ -4,7 +4,9 @@
 // ReSharper disable InconsistentNaming
 
 using System;
+using System.IO;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
@@ -30,6 +32,27 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             Assert.Throws<NotSupportedException>(() => provider.GetImage(new TiffDecoder()));
         }
 
+        [Theory]
+        [InlineData(TestImages.Tiff.RgbUncompressed, 24, 256, 256, 300, 300, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(TestImages.Tiff.SmallRgbDeflate, 24, 32, 32, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(TestImages.Tiff.Calliphora_GrayscaleUncompressed, 8, 804, 1198, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        public void Identify(string imagePath, int expectedPixelSize, int expectedWidth, int expectedHeight, double expectedHResolution, double expectedVResolution, PixelResolutionUnit expectedResolutionUnit)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using (var stream = new MemoryStream(testFile.Bytes, false))
+            {
+                IImageInfo info = Image.Identify(stream);
+
+                Assert.Equal(expectedPixelSize, info.PixelType?.BitsPerPixel);
+                Assert.Equal(expectedWidth, info.Width);
+                Assert.Equal(expectedHeight, info.Height);
+                Assert.NotNull(info.Metadata);
+                Assert.Equal(expectedHResolution, info.Metadata.HorizontalResolution);
+                Assert.Equal(expectedVResolution, info.Metadata.VerticalResolution);
+                Assert.Equal(expectedResolutionUnit, info.Metadata.ResolutionUnits);
+            }
+        }
+
         [Theory]
         [WithFileCollection(nameof(SingleTestImages), PixelTypes.Rgba32)]
         public void Decode<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/Formats/Tiff/TiffMetadataTests.cs

@@ -8,7 +8,6 @@ using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 {
-    [Trait("Category", "Tiff.BlackBox")]
     [Trait("Category", "Tiff")]
     public class TiffMetadataTests
     {
@@ -31,6 +30,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
                 else
                 {
                     Assert.NotNull(meta.XmpProfile);
+                    Assert.Equal(2599, meta.XmpProfile.Length);
                 }
             }
         }
@@ -53,25 +53,33 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
                 TiffFrameMetadata frame = image.Frames.RootFrame.Metadata.GetTiffMetadata();
                 Assert.Equal(32u, frame.Width);
                 Assert.Equal(32u, frame.Height);
-                Assert.Equal(new ushort[] { 8, 8, 8 }, frame.BitsPerSample);
+                Assert.Equal(new ushort[] { 4 }, frame.BitsPerSample);
                 Assert.Equal(TiffCompression.Lzw, frame.Compression);
-                Assert.Equal(TiffPhotometricInterpretation.Rgb, frame.PhotometricInterpretation);
+                Assert.Equal(TiffPhotometricInterpretation.PaletteColor, frame.PhotometricInterpretation);
                 Assert.Equal("This is Название", frame.ImageDescription);
                 Assert.Equal("This is Изготовитель камеры", frame.Make);
                 Assert.Equal("This is Модель камеры", frame.Model);
                 Assert.Equal(new uint[] { 8 }, frame.StripOffsets);
+                Assert.Equal(1, frame.SamplesPerPixel);
                 Assert.Equal(32u, frame.RowsPerStrip);
-                Assert.Equal(new uint[] { 750 }, frame.StripByteCounts);
+                Assert.Equal(new uint[] { 297 }, frame.StripByteCounts);
                 Assert.Equal(10, frame.HorizontalResolution);
                 Assert.Equal(10, frame.VerticalResolution);
                 Assert.Equal(TiffPlanarConfiguration.Chunky, frame.PlanarConfiguration);
                 Assert.Equal(TiffResolutionUnit.Inch, frame.ResolutionUnit);
                 Assert.Equal("IrfanView", frame.Software);
                 Assert.Equal(null, frame.DateTime);
-                Assert.Equal("This is;Автор", frame.Artist);
+                Assert.Equal("This is author1;Author2", frame.Artist);
                 Assert.Equal(null, frame.HostComputer);
-                Assert.Equal(null, frame.ColorMap);
+                Assert.Equal(48, frame.ColorMap.Length);
+                Assert.Equal(10537, frame.ColorMap[0]);
+                Assert.Equal(14392, frame.ColorMap[1]);
+                Assert.Equal(58596, frame.ColorMap[46]);
+                Assert.Equal(3855, frame.ColorMap[47]);
+
                 Assert.Equal(null, frame.ExtraSamples);
+                Assert.Equal(TiffPredictor.None, frame.Predictor);
+                Assert.Equal(null, frame.SampleFormat);
                 Assert.Equal("This is Авторские права", frame.Copyright);
             }
         }

tests/ImageSharp.Tests/TestImages.cs

@@ -502,9 +502,9 @@ namespace SixLabors.ImageSharp.Tests
 
             public const string Calliphora_GrayscaleUncompressed = "Tiff/Calliphora_grayscale_uncompressed.tiff";
             public const string Calliphora_PaletteUncompressed = "Tiff/Calliphora_palette_uncompressed.tiff";
-            public const string Calliphora_RgbDeflate = "Tiff/Calliphora_rgb_deflate.tiff";
+            public const string Calliphora_RgbDeflate_Predictor = "Tiff/Calliphora_rgb_deflate.tiff";
             public const string Calliphora_RgbJpeg = "Tiff/Calliphora_rgb_jpeg.tiff";
-            public const string Calliphora_RgbLzw = "Tiff/Calliphora_rgb_lzw.tiff";
+            public const string Calliphora_RgbLzwe_Predictor = "Tiff/Calliphora_rgb_lzw.tiff";
             public const string Calliphora_RgbPackbits = "Tiff/Calliphora_rgb_packbits.tiff";
             public const string Calliphora_RgbUncompressed = "Tiff/Calliphora_rgb_uncompressed.tiff";
 
@@ -512,32 +512,35 @@ namespace SixLabors.ImageSharp.Tests
             public const string GrayscaleUncompressed = "Tiff/grayscale_uncompressed.tiff";
             public const string PaletteDeflateMultistrip = "Tiff/palette_grayscale_deflate_multistrip.tiff";
             public const string PaletteUncompressed = "Tiff/palette_uncompressed.tiff";
-            public const string RgbDeflate = "Tiff/rgb_deflate.tiff";
+            public const string RgbDeflate_Predictor = "Tiff/rgb_deflate.tiff";
             public const string RgbDeflateMultistrip = "Tiff/rgb_deflate_multistrip.tiff";
             public const string RgbJpeg = "Tiff/rgb_jpeg.tiff";
-            public const string RgbLzw = "Tiff/rgb_lzw.tiff";
-            public const string RgbLzwMultistrip = "Tiff/rgb_lzw_multistrip.tiff";
+            public const string RgbLzw_Predictor = "Tiff/rgb_lzw.tiff";
+            public const string RgbLzwMultistrip_Predictor = "Tiff/rgb_lzw_multistrip.tiff";
             public const string RgbPackbits = "Tiff/rgb_packbits.tiff";
             public const string RgbPackbitsMultistrip = "Tiff/rgb_packbits_multistrip.tiff";
             public const string RgbUncompressed = "Tiff/rgb_uncompressed.tiff";
 
+            public const string SmallRgbDeflate = "Tiff/rgb_small_deflate.tiff";
+            public const string SmallRgbLzw = "Tiff/rgb_small_lzw.tiff";
+
             public const string RgbUncompressedTiled = "Tiff/rgb_uncompressed_tiled.tiff";
             public const string MultiframeDifferentSizeTiled = "Tiff/multipage_ withPreview_differentSize_tiled.tiff";
 
-            public const string MultiframeLzw = "Tiff/multipage_lzw.tiff";
+            public const string MultiframeLzw_Predictor = "Tiff/multipage_lzw.tiff";
             public const string MultiframeDeflateWithPreview = "Tiff/multipage_deflate_withPreview.tiff";
             public const string MultiframeDifferentSize = "Tiff/multipage_differentSize.tiff";
             public const string MultiframeDifferentVariants = "Tiff/multipage_differentVariants.tiff";
 
             public const string SampleMetadata = "Tiff/metadata_sample.tiff";
 
-            public static readonly string[] All = { Calliphora_GrayscaleUncompressed, Calliphora_PaletteUncompressed, Calliphora_RgbDeflate, Calliphora_RgbLzw, Calliphora_RgbPackbits, Calliphora_RgbUncompressed, GrayscaleDeflateMultistrip, GrayscaleUncompressed, PaletteDeflateMultistrip, PaletteUncompressed, RgbDeflate, RgbDeflateMultistrip, /*RgbJpeg,*/ RgbLzw, RgbLzwMultistrip, RgbPackbits, RgbPackbitsMultistrip, RgbUncompressed, MultiframeLzw, /*MultiFrameDifferentVariants,*/ SampleMetadata, };
+            public static readonly string[] All = { Calliphora_GrayscaleUncompressed, Calliphora_PaletteUncompressed, /*Calliphora_RgbDeflate_Predictor, Calliphora_RgbLzwe_Predictor, */ Calliphora_RgbPackbits, Calliphora_RgbUncompressed, GrayscaleDeflateMultistrip, GrayscaleUncompressed, PaletteDeflateMultistrip, PaletteUncompressed, /*RgbDeflate_Predictor,*/ RgbDeflateMultistrip, /*RgbJpeg,*/ /*RgbLzw_Predictor, RgbLzwMultistrip_Predictor,*/ RgbPackbits, RgbPackbitsMultistrip, RgbUncompressed, /* MultiframeLzw_Predictor, MultiFrameDifferentVariants, SampleMetadata,*/ SmallRgbDeflate, SmallRgbLzw };
 
-            public static readonly string[] Multiframes = { MultiframeLzw, MultiframeDeflateWithPreview /*MultiFrameDifferentSize, MultiframeDifferentSizeTiled, MultiFrameDifferentVariants,*/ };
+            public static readonly string[] Multiframes = { MultiframeDeflateWithPreview /*MultiframeLzw_Predictor, MultiFrameDifferentSize, MultiframeDifferentSizeTiled, MultiFrameDifferentVariants,*/ };
 
             public static readonly string[] Metadata = { SampleMetadata };
 
-            public static readonly string[] NotSupported = { Calliphora_RgbJpeg, RgbJpeg, RgbUncompressedTiled, MultiframeDifferentSize, MultiframeDifferentVariants };
+            public static readonly string[] NotSupported = { Calliphora_RgbJpeg, Calliphora_RgbDeflate_Predictor, Calliphora_RgbLzwe_Predictor, RgbDeflate_Predictor, RgbLzw_Predictor, RgbLzwMultistrip_Predictor, RgbJpeg, RgbUncompressedTiled, MultiframeLzw_Predictor, MultiframeDifferentSize, MultiframeDifferentVariants };
         }
     }
 }