Add test cases for tiled 32 bit gray tiff's

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

@@ -83,6 +83,18 @@ internal static class HorizontalPredictor
                     UndoGray16BitLittleEndianRow(pixelBytes, width, y);
                 }
 
+                break;
+            case TiffColorType.BlackIsZero32:
+            case TiffColorType.WhiteIsZero32:
+                if (isBigEndian)
+                {
+                    UndoGray32BitBigEndianRow(pixelBytes, width, y);
+                }
+                else
+                {
+                    UndoGray32BitLittleEndianRow(pixelBytes, width, y);
+                }
+
                 break;
             case TiffColorType.Rgb888:
             case TiffColorType.CieLab:
@@ -266,6 +278,46 @@ internal static class HorizontalPredictor
         }
     }
 
+    private static void UndoGray32BitBigEndianRow(Span<byte> pixelBytes, int width, int y)
+    {
+        int rowBytesCount = width * 4;
+        int height = pixelBytes.Length / rowBytesCount;
+
+        int offset = 0;
+        Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
+        uint pixelValue = TiffUtilities.ConvertToUIntBigEndian(rowBytes.Slice(offset, 4));
+        offset += 4;
+
+        for (int x = 1; x < width; x++)
+        {
+            Span<byte> rowSpan = rowBytes.Slice(offset, 4);
+            uint diff = TiffUtilities.ConvertToUIntBigEndian(rowSpan);
+            pixelValue += diff;
+            BinaryPrimitives.WriteUInt32BigEndian(rowSpan, pixelValue);
+            offset += 4;
+        }
+    }
+
+    private static void UndoGray32BitLittleEndianRow(Span<byte> pixelBytes, int width, int y)
+    {
+        int rowBytesCount = width * 4;
+        int height = pixelBytes.Length / rowBytesCount;
+
+        int offset = 0;
+        Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
+        uint pixelValue = TiffUtilities.ConvertToUIntLittleEndian(rowBytes.Slice(offset, 4));
+        offset += 4;
+
+        for (int x = 1; x < width; x++)
+        {
+            Span<byte> rowSpan = rowBytes.Slice(offset, 4);
+            uint diff = TiffUtilities.ConvertToUIntLittleEndian(rowSpan);
+            pixelValue += diff;
+            BinaryPrimitives.WriteUInt32LittleEndian(rowSpan, pixelValue);
+            offset += 4;
+        }
+    }
+
     private static void UndoGray32Bit(Span<byte> pixelBytes, int width, bool isBigEndian)
     {
         int rowBytesCount = width * 4;
@@ -274,38 +326,14 @@ internal static class HorizontalPredictor
         {
             for (int y = 0; y < height; y++)
             {
-                int offset = 0;
-                Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
-                uint pixelValue = TiffUtilities.ConvertToUIntBigEndian(rowBytes.Slice(offset, 4));
-                offset += 4;
-
-                for (int x = 1; x < width; x++)
-                {
-                    Span<byte> rowSpan = rowBytes.Slice(offset, 4);
-                    uint diff = TiffUtilities.ConvertToUIntBigEndian(rowSpan);
-                    pixelValue += diff;
-                    BinaryPrimitives.WriteUInt32BigEndian(rowSpan, pixelValue);
-                    offset += 4;
-                }
+                UndoGray32BitBigEndianRow(pixelBytes, width, y);
             }
         }
         else
         {
             for (int y = 0; y < height; y++)
             {
-                int offset = 0;
-                Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
-                uint pixelValue = TiffUtilities.ConvertToUIntLittleEndian(rowBytes.Slice(offset, 4));
-                offset += 4;
-
-                for (int x = 1; x < width; x++)
-                {
-                    Span<byte> rowSpan = rowBytes.Slice(offset, 4);
-                    uint diff = TiffUtilities.ConvertToUIntLittleEndian(rowSpan);
-                    pixelValue += diff;
-                    BinaryPrimitives.WriteUInt32LittleEndian(rowSpan, pixelValue);
-                    offset += 4;
-                }
+                UndoGray32BitLittleEndianRow(pixelBytes, width, y);
             }
         }
     }

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

@@ -92,6 +92,8 @@ public class TiffDecoderTests : TiffDecoderBaseTester
     [WithFile(TiledGrayDeflateCompressedWithPredictor, PixelTypes.Rgba32)]
     [WithFile(TiledGray16BitLittleEndianDeflateCompressedWithPredictor, PixelTypes.Rgba32)]
     [WithFile(TiledGray16BitBigEndianDeflateCompressedWithPredictor, PixelTypes.Rgba32)]
+    [WithFile(TiledGray32BitLittleEndianDeflateCompressedWithPredictor, PixelTypes.Rgba32)]
+    [WithFile(TiledGray32BitBigEndianDeflateCompressedWithPredictor, PixelTypes.Rgba32)]
     public void TiffDecoder_CanDecode_Tiled<TPixel>(TestImageProvider<TPixel> provider)
         where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
 

tests/ImageSharp.Tests/TestImages.cs

@@ -991,6 +991,8 @@ public static class TestImages
         public const string TiledGrayDeflateCompressedWithPredictor = "Tiff/tiled_gray_deflate_compressed_predictor.tiff";
         public const string TiledGray16BitLittleEndianDeflateCompressedWithPredictor = "Tiff/tiled_gray_16bit_little_endian_deflate_compressed_predictor.tiff";
         public const string TiledGray16BitBigEndianDeflateCompressedWithPredictor = "Tiff/tiled_gray_16bit_big_endian_deflate_compressed_predictor.tiff";
+        public const string TiledGray32BitLittleEndianDeflateCompressedWithPredictor = "Tiff/tiled_gray_32bit_little_endian_deflate_compressed_predictor.tiff";
+        public const string TiledGray32BitBigEndianDeflateCompressedWithPredictor = "Tiff/tiled_gray_32bit_big_endian_deflate_compressed_predictor.tiff";
 
         // Images with alpha channel.
         public const string Rgba2BitUnassociatedAlpha = "Tiff/RgbaUnassociatedAlpha2bit.tiff";

tests/Images/Input/Tiff/tiled_gray_32bit_big_endian_deflate_compressed_predictor.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b674439ce46a39377279755ffa372c5bd863ac7787165e95590c0a9c6c5d681e
+size 82469

tests/Images/Input/Tiff/tiled_gray_32bit_little_endian_deflate_compressed_predictor.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3acfecebb3db8b549b7a20a3fdd967ba5a4cbb95cbb9b4a59d332fa6ec809278
+size 82519