Add method UndoTile in HorizontalPredictor

Author: brianpopow

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

@@ -24,6 +24,8 @@ internal sealed class DeflateTiffCompression : TiffBaseDecompressor
 
     private readonly bool isTiled;
 
+    private readonly int tileWidth;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="DeflateTiffCompression" /> class.
     /// </summary>
@@ -34,12 +36,14 @@ internal sealed class DeflateTiffCompression : TiffBaseDecompressor
     /// <param name="predictor">The tiff predictor used.</param>
     /// <param name="isBigEndian">if set to <c>true</c> decodes the pixel data as big endian, otherwise as little endian.</param>
     /// <param name="isTiled">Flag indicates, if the image is a tiled image.</param>
-    public DeflateTiffCompression(MemoryAllocator memoryAllocator, int width, int bitsPerPixel, TiffColorType colorType, TiffPredictor predictor, bool isBigEndian, bool isTiled)
+    /// <param name="tileWidth">Number of pixels in a tile row.</param>
+    public DeflateTiffCompression(MemoryAllocator memoryAllocator, int width, int bitsPerPixel, TiffColorType colorType, TiffPredictor predictor, bool isBigEndian, bool isTiled, int tileWidth)
         : base(memoryAllocator, width, bitsPerPixel, predictor)
     {
         this.colorType = colorType;
         this.isBigEndian = isBigEndian;
         this.isTiled = isTiled;
+        this.tileWidth = tileWidth;
     }
 
     /// <inheritdoc/>
@@ -73,9 +77,16 @@ protected override void Decompress(BufferedReadStream stream, int byteCount, int
         }
 
         // When the image is tiled, undoing the horizontal predictor will be done for each tile row in the DecodeTilesChunky() method.
-        if (this.Predictor == TiffPredictor.Horizontal && !this.isTiled)
+        if (this.Predictor == TiffPredictor.Horizontal)
         {
-            HorizontalPredictor.Undo(buffer, this.Width, this.colorType, this.isBigEndian);
+            if (this.isTiled)
+            {
+                HorizontalPredictor.UndoTile(buffer, this.tileWidth, this.colorType, this.isBigEndian);
+            }
+            else
+            {
+                HorizontalPredictor.Undo(buffer, this.Width, this.colorType, this.isBigEndian);
+            }
         }
     }
 

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

@@ -62,6 +62,14 @@ public static void Undo(Span<byte> pixelBytes, int width, TiffColorType colorTyp
         }
     }
 
+    public static void UndoTile(Span<byte> pixelBytes, int tileWidth, TiffColorType colorType, bool isBigEndian)
+    {
+        for (int y = 0; y < tileWidth; y++)
+        {
+            UndoRow(pixelBytes, tileWidth, y, colorType, isBigEndian);
+        }
+    }
+
     /// <summary>
     /// Inverts the horizontal predictor for one row.
     /// </summary>

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

@@ -4,7 +4,6 @@
 using SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors;
 using SixLabors.ImageSharp.Formats.Tiff.Constants;
 using SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation;
-using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Tiff.Compression;
@@ -25,7 +24,8 @@ public static TiffBaseDecompressor Create(
         uint oldJpegStartOfImageMarker,
         TiffFillOrder fillOrder,
         ByteOrder byteOrder,
-        bool isTiled = false)
+        bool isTiled = false,
+        int tileWidth = 0)
     {
         switch (method)
         {
@@ -41,7 +41,7 @@ public static TiffBaseDecompressor Create(
 
             case TiffDecoderCompressionType.Deflate:
                 DebugGuard.IsTrue(faxOptions == FaxCompressionOptions.None, "No fax compression options are expected");
-                return new DeflateTiffCompression(allocator, width, bitsPerPixel, colorType, predictor, byteOrder == ByteOrder.BigEndian, isTiled);
+                return new DeflateTiffCompression(allocator, width, bitsPerPixel, colorType, predictor, byteOrder == ByteOrder.BigEndian, isTiled, tileWidth);
 
             case TiffDecoderCompressionType.Lzw:
                 DebugGuard.IsTrue(faxOptions == FaxCompressionOptions.None, "No fax compression options are expected");

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -679,8 +679,7 @@ private void DecodeTilesChunky<TPixel>(
         using IMemoryOwner<byte> tileBuffer = this.memoryAllocator.Allocate<byte>(bytesPerTileRow * tileLength, AllocationOptions.Clean);
         Span<byte> tileBufferSpan = tileBuffer.GetSpan();
 
-        bool isTiled = true;
-        using TiffBaseDecompressor decompressor = this.CreateDecompressor<TPixel>(frame.Width, bitsPerPixel, isTiled);
+        using TiffBaseDecompressor decompressor = this.CreateDecompressor<TPixel>(frame.Width, bitsPerPixel, true, tileWidth);
         TiffBaseColorDecoder<TPixel> colorDecoder = this.CreateChunkyColorDecoder<TPixel>();
 
         int tileIndex = 0;
@@ -748,7 +747,7 @@ private TiffBasePlanarColorDecoder<TPixel> CreatePlanarColorDecoder<TPixel>()
             this.YcbcrSubSampling,
             this.byteOrder);
 
-    private TiffBaseDecompressor CreateDecompressor<TPixel>(int frameWidth, int bitsPerPixel, bool isTiled = false)
+    private TiffBaseDecompressor CreateDecompressor<TPixel>(int frameWidth, int bitsPerPixel, bool isTiled = false, int tileWidth = 0)
         where TPixel : unmanaged, IPixel<TPixel> =>
         TiffDecompressorsFactory.Create(
             this.Options,
@@ -764,7 +763,8 @@ private TiffBaseDecompressor CreateDecompressor<TPixel>(int frameWidth, int bits
             this.OldJpegCompressionStartOfImageMarker.GetValueOrDefault(),
             this.FillOrder,
             this.byteOrder,
-            isTiled);
+            isTiled,
+            tileWidth);
 
     private IMemoryOwner<ulong> ConvertNumbers(Array array, out Span<ulong> span)
     {

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

@@ -23,7 +23,7 @@ public void Compress_Decompress_Roundtrip_Works(byte[] data)
         using BufferedReadStream stream = CreateCompressedStream(data);
         byte[] buffer = new byte[data.Length];
 
-        using var decompressor = new DeflateTiffCompression(Configuration.Default.MemoryAllocator, 10, 8, TiffColorType.BlackIsZero8, TiffPredictor.None, false, false);
+        using var decompressor = new DeflateTiffCompression(Configuration.Default.MemoryAllocator, 10, 8, TiffColorType.BlackIsZero8, TiffPredictor.None, false, false, 0);
 
         decompressor.Decompress(stream, 0, (uint)stream.Length, 1, buffer, default);