Merge pull request #3124 from SixLabors/bp/decodePxr24

Add support for decoding PXR24 compressed Exr images

src/ImageSharp/Formats/Exr/Compression/Compressors/NoneExrCompressor.cs

@@ -17,8 +17,10 @@ internal class NoneExrCompressor : ExrBaseCompressor
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">Bytes per row block.</param>
     /// <param name="bytesPerRow">Bytes per pixel row.</param>
-    public NoneExrCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(output, allocator, bytesPerBlock, bytesPerRow)
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
+    public NoneExrCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(output, allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
     {
     }
 

src/ImageSharp/Formats/Exr/Compression/Compressors/ZipExrCompressor.cs

@@ -24,9 +24,11 @@ internal class ZipExrCompressor : ExrBaseCompressor
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
     /// <param name="compressionLevel">The compression level for deflate compression.</param>
-    public ZipExrCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, DeflateCompressionLevel compressionLevel)
-        : base(output, allocator, bytesPerBlock, bytesPerRow)
+    public ZipExrCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width, DeflateCompressionLevel compressionLevel)
+        : base(output, allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
     {
         this.compressionLevel = compressionLevel;
         this.buffer = allocator.Allocate<byte>((int)bytesPerBlock);

src/ImageSharp/Formats/Exr/Compression/Decompressors/B44ExrCompression.cs

@@ -13,10 +13,6 @@ namespace SixLabors.ImageSharp.Formats.Exr.Compression.Decompressors;
 /// </summary>
 internal class B44ExrCompression : ExrBaseDecompressor
 {
-    private readonly int width;
-
-    private readonly uint rowsPerBlock;
-
     private readonly int channelCount;
 
     private readonly byte[] scratch = new byte[14];
@@ -31,14 +27,12 @@ internal class B44ExrCompression : ExrBaseDecompressor
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per pixel row block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
-    /// <param name="rowsPerBlock">The rows per block.</param>
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
     /// <param name="width">The width of a pixel row in pixels.</param>
     /// <param name="channelCount">The number of channels of the image.</param>
     public B44ExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width, int channelCount)
-        : base(allocator, bytesPerBlock, bytesPerRow)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
     {
-        this.width = width;
-        this.rowsPerBlock = rowsPerBlock;
         this.channelCount = channelCount;
         this.tmpBuffer = allocator.Allocate<ushort>((int)(width * rowsPerBlock * channelCount));
     }
@@ -52,19 +46,19 @@ internal class B44ExrCompression : ExrBaseDecompressor
         int bytesLeft = (int)compressedBytes;
         for (int i = 0; i < this.channelCount && bytesLeft > 0; i++)
         {
-            for (int y = 0; y < this.rowsPerBlock; y += 4)
+            for (int y = 0; y < this.RowsPerBlock; y += 4)
             {
-                Span<ushort> row0 = decompressed.Slice(outputOffset, this.width);
-                outputOffset += this.width;
-                Span<ushort> row1 = decompressed.Slice(outputOffset, this.width);
-                outputOffset += this.width;
-                Span<ushort> row2 = decompressed.Slice(outputOffset, this.width);
-                outputOffset += this.width;
-                Span<ushort> row3 = decompressed.Slice(outputOffset, this.width);
-                outputOffset += this.width;
+                Span<ushort> row0 = decompressed.Slice(outputOffset, this.Width);
+                outputOffset += this.Width;
+                Span<ushort> row1 = decompressed.Slice(outputOffset, this.Width);
+                outputOffset += this.Width;
+                Span<ushort> row2 = decompressed.Slice(outputOffset, this.Width);
+                outputOffset += this.Width;
+                Span<ushort> row3 = decompressed.Slice(outputOffset, this.Width);
+                outputOffset += this.Width;
 
                 int rowOffset = 0;
-                for (int x = 0; x < this.width && bytesLeft > 0; x += 4)
+                for (int x = 0; x < this.Width && bytesLeft > 0; x += 4)
                 {
                     int bytesRead = stream.Read(this.scratch, 0, 3);
                     if (bytesRead == 0)
@@ -72,6 +66,7 @@ internal class B44ExrCompression : ExrBaseDecompressor
                         ExrThrowHelper.ThrowInvalidImageContentException("Could not read enough data from the stream!");
                     }
 
+                    // Check if 3-byte encoded flat field.
                     if (this.scratch[2] >= 13 << 2)
                     {
                         Unpack3(this.scratch, this.s);
@@ -89,8 +84,8 @@ internal class B44ExrCompression : ExrBaseDecompressor
                         bytesLeft -= 14;
                     }
 
-                    int n = x + 3 < this.width ? 4 : this.width - x;
-                    if (y + 3 < this.rowsPerBlock)
+                    int n = x + 3 < this.Width ? 4 : this.Width - x;
+                    if (y + 3 < this.RowsPerBlock)
                     {
                         this.s.AsSpan(0, n).CopyTo(row0[rowOffset..]);
                         this.s.AsSpan(4, n).CopyTo(row1[rowOffset..]);
@@ -100,12 +95,12 @@ internal class B44ExrCompression : ExrBaseDecompressor
                     else
                     {
                         this.s.AsSpan(0, n).CopyTo(row0[rowOffset..]);
-                        if (y + 1 < this.rowsPerBlock)
+                        if (y + 1 < this.RowsPerBlock)
                         {
                             this.s.AsSpan(4, n).CopyTo(row1[rowOffset..]);
                         }
 
-                        if (y + 2 < this.rowsPerBlock)
+                        if (y + 2 < this.RowsPerBlock)
                         {
                             this.s.AsSpan(8, n).CopyTo(row2[rowOffset..]);
                         }
@@ -124,16 +119,16 @@ internal class B44ExrCompression : ExrBaseDecompressor
         // Rearrange the decompressed data such that the data for each scan line form a contiguous block.
         int offsetDecompressed = 0;
         int offsetOutput = 0;
-        int blockSize = (int)(this.width * this.rowsPerBlock);
-        for (int y = 0; y < this.rowsPerBlock; y++)
+        int blockSize = (int)(this.Width * this.RowsPerBlock);
+        for (int y = 0; y < this.RowsPerBlock; y++)
         {
             for (int i = 0; i < this.channelCount; i++)
             {
-                decompressed.Slice(offsetDecompressed + (i * blockSize), this.width).CopyTo(outputBuffer[offsetOutput..]);
-                offsetOutput += this.width;
+                decompressed.Slice(offsetDecompressed + (i * blockSize), this.Width).CopyTo(outputBuffer[offsetOutput..]);
+                offsetOutput += this.Width;
             }
 
-            offsetDecompressed += this.width;
+            offsetDecompressed += this.Width;
         }
     }
 

src/ImageSharp/Formats/Exr/Compression/Decompressors/NoneExrCompression.cs

@@ -17,8 +17,10 @@ internal class NoneExrCompression : ExrBaseDecompressor
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per pixel row block.</param>
     /// <param name="bytesPerRow">The bytes per pixel row.</param>
-    public NoneExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(allocator, bytesPerBlock, bytesPerRow)
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The number of pixels per row.</param>
+    public NoneExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
     {
     }
 

src/ImageSharp/Formats/Exr/Compression/Decompressors/Pxr24Compression.cs

@@ -0,0 +1,153 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Buffers;
+using System.Runtime.InteropServices;
+using SixLabors.ImageSharp.Formats.Exr.Constants;
+using SixLabors.ImageSharp.IO;
+using SixLabors.ImageSharp.Memory;
+
+namespace SixLabors.ImageSharp.Formats.Exr.Compression.Decompressors;
+
+/// <summary>
+/// Implementation of PXR24 decompressor for EXR image data.
+/// </summary>
+internal class Pxr24Compression : ExrBaseDecompressor
+{
+    private readonly IMemoryOwner<byte> tmpBuffer;
+
+    private readonly int channelCount;
+
+    private readonly ExrPixelType pixelType;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Pxr24Compression" /> class.
+    /// </summary>
+    /// <param name="allocator">The memory allocator.</param>
+    /// <param name="bytesPerBlock">The bytes per pixel row block.</param>
+    /// <param name="bytesPerRow">The bytes per pixel row.</param>
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
+    /// <param name="channelCount">The number of channels for a pixel.</param>
+    /// <param name="pixelType">The pixel type.</param>
+    public Pxr24Compression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width, int channelCount, ExrPixelType pixelType)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
+    {
+        this.tmpBuffer = allocator.Allocate<byte>((int)bytesPerBlock);
+        this.channelCount = channelCount;
+        this.pixelType = pixelType;
+    }
+
+    /// <inheritdoc/>
+    public override void Decompress(BufferedReadStream stream, uint compressedBytes, Span<byte> buffer)
+    {
+        Span<byte> uncompressed = this.tmpBuffer.GetSpan();
+        Span<ushort> outputBufferHalf = MemoryMarshal.Cast<byte, ushort>(buffer);
+        Span<uint> outputBufferFloat = MemoryMarshal.Cast<byte, uint>(buffer);
+        Span<uint> outputBufferUint = MemoryMarshal.Cast<byte, uint>(buffer);
+
+        uint uncompressedBytes = this.BytesPerBlock;
+        UndoZipCompression(stream, compressedBytes, uncompressed, uncompressedBytes);
+
+        int lastIn = 0;
+        int outputOffset = 0;
+        for (int y = 0; y < this.RowsPerBlock; y++)
+        {
+            for (int c = 0; c < this.channelCount; c++)
+            {
+                switch (this.pixelType)
+                {
+                    case ExrPixelType.UnsignedInt:
+                    {
+                        int offsetT0 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT1 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT2 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT3 = lastIn;
+                        lastIn += this.Width;
+
+                        uint pixel = 0;
+                        for (int x = 0; x < this.Width; x++)
+                        {
+                            uint t0 = uncompressed[offsetT0];
+                            uint t1 = uncompressed[offsetT1];
+                            uint t2 = uncompressed[offsetT2];
+                            uint t3 = uncompressed[offsetT3];
+                            uint diff = (t0 << 24) | (t1 << 16) | (t2 << 8) | t3;
+
+                            pixel += diff;
+                            outputBufferUint[outputOffset] = pixel;
+
+                            offsetT0++;
+                            offsetT1++;
+                            offsetT2++;
+                            offsetT3++;
+                            outputOffset++;
+                        }
+
+                        break;
+                    }
+
+                    case ExrPixelType.Half:
+                    {
+                        int offsetT0 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT1 = lastIn;
+                        lastIn += this.Width;
+
+                        uint pixel = 0;
+                        for (int x = 0; x < this.Width; x++)
+                        {
+                            uint t0 = uncompressed[offsetT0];
+                            uint t1 = uncompressed[offsetT1];
+                            uint diff = (t0 << 8) | t1;
+
+                            pixel += diff;
+                            outputBufferHalf[outputOffset] = (ushort)pixel;
+
+                            offsetT0++;
+                            offsetT1++;
+                            outputOffset++;
+                        }
+
+                        break;
+                    }
+
+                    case ExrPixelType.Float:
+                    {
+                        int offsetT0 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT1 = lastIn;
+                        lastIn += this.Width;
+                        int offsetT2 = lastIn;
+                        lastIn += this.Width;
+
+                        uint pixel = 0;
+                        for (int x = 0; x < this.Width; x++)
+                        {
+                            uint t0 = uncompressed[offsetT0];
+                            uint t1 = uncompressed[offsetT1];
+                            uint t2 = uncompressed[offsetT2];
+                            uint diff = (t0 << 24) | (t1 << 16) | (t2 << 8);
+
+                            pixel += diff;
+                            outputBufferFloat[outputOffset] = pixel;
+
+                            offsetT0++;
+                            offsetT1++;
+                            offsetT2++;
+                            outputOffset++;
+                        }
+
+                        break;
+                    }
+                }
+            }
+        }
+    }
+
+    /// <inheritdoc/>
+    protected override void Dispose(bool disposing) => this.tmpBuffer.Dispose();
+}

src/ImageSharp/Formats/Exr/Compression/Decompressors/RunLengthExrCompression.cs

@@ -14,16 +14,16 @@ internal class RunLengthExrCompression : ExrBaseDecompressor
 {
     private readonly IMemoryOwner<byte> tmpBuffer;
 
-    private readonly ushort[] s = new ushort[16];
-
     /// <summary>
     /// Initializes a new instance of the <see cref="RunLengthExrCompression" /> class.
     /// </summary>
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per pixel row block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
-    public RunLengthExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(allocator, bytesPerBlock, bytesPerRow) => this.tmpBuffer = allocator.Allocate<byte>((int)bytesPerBlock);
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
+    public RunLengthExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width) => this.tmpBuffer = allocator.Allocate<byte>((int)bytesPerBlock);
 
     /// <inheritdoc/>
     public override void Decompress(BufferedReadStream stream, uint compressedBytes, Span<byte> buffer)

src/ImageSharp/Formats/Exr/Compression/Decompressors/ZipExrCompression.cs

@@ -2,8 +2,6 @@
 // Licensed under the Six Labors Split License.
 
 using System.Buffers;
-using System.IO.Compression;
-using SixLabors.ImageSharp.Compression.Zlib;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Memory;
 
@@ -22,41 +20,18 @@ internal class ZipExrCompression : ExrBaseDecompressor
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per pixel row block.</param>
     /// <param name="bytesPerRow">The bytes per pixel row.</param>
-    public ZipExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(allocator, bytesPerBlock, bytesPerRow) => this.tmpBuffer = allocator.Allocate<byte>((int)bytesPerBlock);
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
+    public ZipExrCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width) => this.tmpBuffer = allocator.Allocate<byte>((int)bytesPerBlock);
 
     /// <inheritdoc/>
     public override void Decompress(BufferedReadStream stream, uint compressedBytes, Span<byte> buffer)
     {
         Span<byte> uncompressed = this.tmpBuffer.GetSpan();
 
-        long pos = stream.Position;
-        using ZlibInflateStream inflateStream = new(
-                   stream,
-                   () =>
-                   {
-                       int left = (int)(compressedBytes - (stream.Position - pos));
-                       return left > 0 ? left : 0;
-                   });
-        inflateStream.AllocateNewBytes((int)this.BytesPerBlock, true);
-        using DeflateStream dataStream = inflateStream.CompressedStream!;
-
-        int totalRead = 0;
-        while (totalRead < buffer.Length)
-        {
-            int bytesRead = dataStream.Read(uncompressed, totalRead, buffer.Length - totalRead);
-            if (bytesRead <= 0)
-            {
-                break;
-            }
-
-            totalRead += bytesRead;
-        }
-
-        if (totalRead == 0)
-        {
-            ExrThrowHelper.ThrowInvalidImageContentException("Could not read enough data for zip compressed image data!");
-        }
+        uint uncompressedBytes = (uint)buffer.Length;
+        int totalRead = UndoZipCompression(stream, compressedBytes, uncompressed, uncompressedBytes);
 
         Reconstruct(uncompressed, (uint)totalRead);
         Interleave(uncompressed, (uint)totalRead, buffer);

src/ImageSharp/Formats/Exr/Compression/ExrBaseCompression.cs

@@ -18,11 +18,15 @@ internal abstract class ExrBaseCompression : IDisposable
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
-    protected ExrBaseCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
+    /// <param name="rowsPerBlock">The number of pixel rows per block.</param>
+    /// <param name="width">The number of pixels of a row.</param>
+    protected ExrBaseCompression(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
     {
         this.Allocator = allocator;
         this.BytesPerBlock = bytesPerBlock;
         this.BytesPerRow = bytesPerRow;
+        this.RowsPerBlock = rowsPerBlock;
+        this.Width = width;
     }
 
     /// <summary>
@@ -45,6 +49,11 @@ internal abstract class ExrBaseCompression : IDisposable
     /// </summary>
     public uint BytesPerBlock { get; }
 
+    /// <summary>
+    /// Gets the number of pixel rows per block.
+    /// </summary>
+    public uint RowsPerBlock { get; }
+
     /// <summary>
     /// Gets the image width.
     /// </summary>

src/ImageSharp/Formats/Exr/Compression/ExrBaseDecompressor.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.IO.Compression;
+using SixLabors.ImageSharp.Compression.Zlib;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Memory;
 
@@ -17,8 +19,10 @@ internal abstract class ExrBaseDecompressor : ExrBaseCompression
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">The bytes per row block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
-    protected ExrBaseDecompressor(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(allocator, bytesPerBlock, bytesPerRow)
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The number of pixels per row.</param>
+    protected ExrBaseDecompressor(MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
     {
     }
 
@@ -30,6 +34,47 @@ internal abstract class ExrBaseDecompressor : ExrBaseCompression
     /// <param name="buffer">The buffer to write the decompressed data to.</param>
     public abstract void Decompress(BufferedReadStream stream, uint compressedBytes, Span<byte> buffer);
 
+    /// <summary>
+    /// Decompresses zip compressed data.
+    /// </summary>
+    /// <param name="stream">The buffered stream to decompress.</param>
+    /// <param name="compressedBytes">The compressed bytes.</param>
+    /// <param name="uncompressed">The buffer to write the uncompressed data to.</param>
+    /// <param name="uncompressedBytes">The uncompressed bytes.</param>
+    /// <returns>The total bytes read from the stream.</returns>
+    protected static int UndoZipCompression(BufferedReadStream stream, uint compressedBytes, Span<byte> uncompressed, uint uncompressedBytes)
+    {
+        long pos = stream.Position;
+        using ZlibInflateStream inflateStream = new(
+                   stream,
+                   () =>
+                   {
+                       int left = (int)(compressedBytes - (stream.Position - pos));
+                       return left > 0 ? left : 0;
+                   });
+        inflateStream.AllocateNewBytes((int)compressedBytes, true);
+        using DeflateStream dataStream = inflateStream.CompressedStream!;
+
+        int totalRead = 0;
+        while (totalRead < uncompressedBytes)
+        {
+            int bytesRead = dataStream.Read(uncompressed, totalRead, (int)uncompressedBytes - totalRead);
+            if (bytesRead <= 0)
+            {
+                break;
+            }
+
+            totalRead += bytesRead;
+        }
+
+        if (totalRead == 0)
+        {
+            ExrThrowHelper.ThrowInvalidImageContentException("Could not read enough data for zip compressed EXR image data!");
+        }
+
+        return totalRead;
+    }
+
     /// <summary>
     /// Integrate over all differences to the previous value in order to
     /// reconstruct sample values.

src/ImageSharp/Formats/Exr/Compression/ExrCompressorFactory.cs

@@ -21,6 +21,8 @@ internal static class ExrCompressorFactory
     /// <param name="output">The output stream.</param>
     /// <param name="bytesPerBlock">The bytes per block.</param>
     /// <param name="bytesPerRow">The bytes per row.</param>
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The witdh of one row in pixels.</param>
     /// <param name="compressionLevel">The deflate compression level.</param>
     /// <returns>A compressor for EXR image data.</returns>
     public static ExrBaseCompressor Create(
@@ -29,11 +31,13 @@ internal static class ExrCompressorFactory
         Stream output,
         uint bytesPerBlock,
         uint bytesPerRow,
+        uint rowsPerBlock,
+        int width,
         DeflateCompressionLevel compressionLevel = DeflateCompressionLevel.DefaultCompression) => method switch
         {
-            ExrCompression.None => new NoneExrCompressor(output, allocator, bytesPerBlock, bytesPerRow),
-            ExrCompression.Zips => new ZipExrCompressor(output, allocator, bytesPerBlock, bytesPerRow, compressionLevel),
-            ExrCompression.Zip => new ZipExrCompressor(output, allocator, bytesPerBlock, bytesPerRow, compressionLevel),
+            ExrCompression.None => new NoneExrCompressor(output, allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width),
+            ExrCompression.Zips => new ZipExrCompressor(output, allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width, compressionLevel),
+            ExrCompression.Zip => new ZipExrCompressor(output, allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width, compressionLevel),
             _ => throw ExrThrowHelper.NotSupportedCompressor(method.ToString()),
         };
 }

src/ImageSharp/Formats/Exr/Compression/ExrDecompressorFactory.cs

@@ -22,6 +22,7 @@ internal static class ExrDecompressorFactory
     /// <param name="bytesPerRow">The bytes per row.</param>
     /// <param name="rowsPerBlock">The rows per block.</param>
     /// <param name="channelCount">The number of image channels.</param>
+    /// <param name="pixelType">The pixel type.</param>
     /// <returns>Decompressor for EXR image data.</returns>
     public static ExrBaseDecompressor Create(
         ExrCompression method,
@@ -30,13 +31,15 @@ internal static class ExrDecompressorFactory
         uint bytesPerBlock,
         uint bytesPerRow,
         uint rowsPerBlock,
-        int channelCount) => method switch
+        int channelCount,
+        ExrPixelType pixelType) => method switch
         {
-            ExrCompression.None => new NoneExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow),
-            ExrCompression.Zips => new ZipExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow),
-            ExrCompression.Zip => new ZipExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow),
-            ExrCompression.RunLengthEncoded => new RunLengthExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow),
+            ExrCompression.None => new NoneExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width),
+            ExrCompression.Zips => new ZipExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width),
+            ExrCompression.Zip => new ZipExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width),
+            ExrCompression.RunLengthEncoded => new RunLengthExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width),
             ExrCompression.B44 => new B44ExrCompression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width, channelCount),
+            ExrCompression.Pxr24 => new Pxr24Compression(memoryAllocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width, channelCount, pixelType),
             _ => throw ExrThrowHelper.NotSupportedDecompressor(nameof(method)),
         };
 }

src/ImageSharp/Formats/Exr/ExrBaseCompressor.cs

@@ -14,8 +14,10 @@ internal abstract class ExrBaseCompressor : ExrBaseCompression
     /// <param name="allocator">The memory allocator.</param>
     /// <param name="bytesPerBlock">Bytes per row block.</param>
     /// <param name="bytesPerRow">Bytes per pixel row.</param>
-    protected ExrBaseCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow)
-        : base(allocator, bytesPerBlock, bytesPerRow)
+    /// <param name="rowsPerBlock">The pixel rows per block.</param>
+    /// <param name="width">The number of pixels per row.</param>
+    protected ExrBaseCompressor(Stream output, MemoryAllocator allocator, uint bytesPerBlock, uint bytesPerRow, uint rowsPerBlock, int width)
+        : base(allocator, bytesPerBlock, bytesPerRow, rowsPerBlock, width)
         => this.Output = output;
 
     /// <summary>

src/ImageSharp/Formats/Exr/ExrDecoderCore.cs

@@ -154,7 +154,15 @@ internal sealed class ExrDecoderCore : ImageDecoderCore
         Span<float> bluePixelData = rowBuffer.GetSpan().Slice(width * 2, width);
         Span<float> alphaPixelData = rowBuffer.GetSpan().Slice(width * 3, width);
 
-        using ExrBaseDecompressor decompressor = ExrDecompressorFactory.Create(this.Compression, this.memoryAllocator, width, bytesPerBlock, bytesPerRow, rowsPerBlock, channelCount);
+        using ExrBaseDecompressor decompressor = ExrDecompressorFactory.Create(
+            this.Compression,
+            this.memoryAllocator,
+            width,
+            bytesPerBlock,
+            bytesPerRow,
+            rowsPerBlock,
+            channelCount,
+            this.PixelType);
 
         int decodedRows = 0;
         while (decodedRows < height)
@@ -219,7 +227,15 @@ internal sealed class ExrDecoderCore : ImageDecoderCore
         Span<uint> bluePixelData = rowBuffer.GetSpan().Slice(width * 2, width);
         Span<uint> alphaPixelData = rowBuffer.GetSpan().Slice(width * 3, width);
 
-        using ExrBaseDecompressor decompressor = ExrDecompressorFactory.Create(this.Compression, this.memoryAllocator, width, bytesPerBlock, bytesPerRow, rowsPerBlock, channelCount);
+        using ExrBaseDecompressor decompressor = ExrDecompressorFactory.Create(
+            this.Compression,
+            this.memoryAllocator,
+            width,
+            bytesPerBlock,
+            bytesPerRow,
+            rowsPerBlock,
+            channelCount,
+            this.PixelType);
 
         int decodedRows = 0;
         while (decodedRows < height)
@@ -846,7 +862,7 @@ internal sealed class ExrDecoderCore : ImageDecoderCore
     /// <returns> True if the compression is supported; otherwise, false>. </returns>
     private bool IsSupportedCompression() => this.Compression switch
     {
-        ExrCompression.None or ExrCompression.Zip or ExrCompression.Zips or ExrCompression.RunLengthEncoded or ExrCompression.B44 => true,
+        ExrCompression.None or ExrCompression.Zip or ExrCompression.Zips or ExrCompression.RunLengthEncoded or ExrCompression.B44 or ExrCompression.Pxr24 => true,
         _ => false,
     };
 

src/ImageSharp/Formats/Exr/ExrEncoderCore.cs

@@ -181,7 +181,7 @@ internal sealed class ExrEncoderCore
         Span<float> blueBuffer = rgbBuffer.GetSpan().Slice(width * 2, width);
         Span<float> alphaBuffer = rgbBuffer.GetSpan().Slice(width * 3, width);
 
-        using ExrBaseCompressor compressor = ExrCompressorFactory.Create(compression, this.memoryAllocator, stream, bytesPerBlock, bytesPerRow);
+        using ExrBaseCompressor compressor = ExrCompressorFactory.Create(compression, this.memoryAllocator, stream, bytesPerBlock, bytesPerRow, rowsPerBlock, width);
 
         ulong[] rowOffsets = new ulong[height];
         for (uint y = 0; y < height; y += rowsPerBlock)
@@ -273,7 +273,7 @@ internal sealed class ExrEncoderCore
         Span<uint> blueBuffer = rgbBuffer.GetSpan().Slice(width * 2, width);
         Span<uint> alphaBuffer = rgbBuffer.GetSpan().Slice(width * 3, width);
 
-        using ExrBaseCompressor compressor = ExrCompressorFactory.Create(compression, this.memoryAllocator, stream, bytesPerBlock, bytesPerRow);
+        using ExrBaseCompressor compressor = ExrCompressorFactory.Create(compression, this.memoryAllocator, stream, bytesPerBlock, bytesPerRow, rowsPerBlock, width);
 
         Rgba128 rgb = default;
         ulong[] rowOffsets = new ulong[height];

tests/ImageSharp.Tests/Formats/Exr/ExrDecoderTests.cs

@@ -36,8 +36,7 @@ public class ExrDecoderTests
         ExrMetadata exrMetaData = image.Metadata.GetExrMetadata();
         image.DebugSave(provider);
 
-        // There is a 0,0059% difference to the Reference decoder.
-        image.CompareToOriginal(provider, ImageComparer.Tolerant(0.0005f), ReferenceDecoder);
+        image.CompareToOriginal(provider, ImageComparer.Exact, ReferenceDecoder);
         Assert.Equal(ExrPixelType.Float, exrMetaData.PixelType);
     }
 
@@ -119,6 +118,29 @@ public class ExrDecoderTests
         image.CompareToOriginal(provider, ImageComparer.Exact, ReferenceDecoder);
     }
 
+    [Theory]
+    [WithFile(TestImages.Exr.Pxr24Half, PixelTypes.Rgba32)]
+    [WithFile(TestImages.Exr.Pxr24Float, PixelTypes.Rgba32)]
+    public void ExrDecoder_CanDecode_Pxr24Compressed<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using Image<TPixel> image = provider.GetImage(ExrDecoder.Instance);
+        image.DebugSave(provider);
+        image.CompareToOriginal(provider, ImageComparer.Exact, ReferenceDecoder);
+    }
+
+    [Theory]
+    [WithFile(TestImages.Exr.Pxr24Uint, PixelTypes.Rgba32)]
+    public void ExrDecoder_CanDecode_Pxr24Compressed_ExrPixelType_Uint<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using Image<TPixel> image = provider.GetImage(ExrDecoder.Instance);
+        image.DebugSave(provider);
+
+        // Compare to Reference here instead using the reference decoder, since uint pixel type is not supported by the Reference decoder.
+        image.CompareToReferenceOutput(provider);
+    }
+
     [Theory]
     [WithFile(TestImages.Exr.B44, PixelTypes.Rgba32)]
     public void ExrDecoder_CanDecode_B44Compressed<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/TestImages.cs

@@ -1388,13 +1388,16 @@ public static class TestImages
         public const string Benchmark = "Exr/Calliphora_benchmark.exr";
         public const string Uncompressed = "Exr/Calliphora_uncompressed.exr";
         public const string UncompressedRgba = "Exr/Calliphora_uncompressed_rgba.exr";
-        public const string UncompressedFloatRgb = "Exr/rgb_float32_uncompressed.exr";
+        public const string UncompressedFloatRgb = "Exr/Calliphora_float_uncompressed.exr";
         public const string UncompressedUintRgb = "Exr/Calliphora_uint32_uncompressed.exr";
         public const string UintRgba = "Exr/rgba_uint_uncompressed.exr";
         public const string Zip = "Exr/Calliphora_zip.exr";
         public const string Zips = "Exr/Calliphora_zips.exr";
         public const string Rle = "Exr/Calliphora_rle.exr";
         public const string B44 = "Exr/Calliphora_b44.exr";
+        public const string Pxr24Half = "Exr/Calliphora_half_pxr24.exr";
+        public const string Pxr24Float = "Exr/Calliphora_float_pxr24.exr";
+        public const string Pxr24Uint = "Exr/Calliphora_uint_pxr24.exr";
         public const string Rgb = "Exr/Calliphora_rgb.exr";
         public const string Gray = "Exr/Calliphora_gray.exr";
     }

tests/Images/External/ReferenceOutput/ExrDecoderTests/ExrDecoder_CanDecode_Pxr24Compressed_ExrPixelType_Uint_Rgba32_Calliphora_uint_pxr24.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f66bf45b5d80e412314341567b8cf240d56b5872f01ce9f3b0d6034d85e8e942
+size 163327

tests/Images/Input/Exr/Calliphora_float_pxr24.exr

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ca6c29eb36395b923298d2bf4ba1f73fd7f081f7b1af2e72b94b92ad2acb638b
+size 226997

tests/Images/Input/Exr/Calliphora_float_uncompressed.exr

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:926996c647c1c54921db0a623e58e5edeb92b447cb4eceb53b8c0e86fd24f11e
+size 720281

tests/Images/Input/Exr/Calliphora_half_pxr24.exr

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:927778a73832b5ad68473e46df6be52076d98294271f2cd0ead66691db41b7bf
+size 195063

tests/Images/Input/Exr/Calliphora_uint_pxr24.exr

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:fc72685224ba818ac77d914f5e4c91162503f88f775e16b5c745baef6bc7b790
+size 187914

tests/Images/Input/Exr/rgb_float32_uncompressed.exr

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:5ab8b71824ca384fc2cde1f74a6f34c38169fa328ccc67f17d08333e9de42f55
-size 243558