Add support for horizontal predictor with 32 bit color tiff's

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

@@ -46,6 +46,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression
                 case TiffColorType.Rgb161616:
                     UndoRgb48Bit(pixelBytes, width, isBigEndian);
                     break;
+                case TiffColorType.Rgb323232:
+                    UndoRgb96Bit(pixelBytes, width, isBigEndian);
+                    break;
             }
         }
 
@@ -315,5 +318,81 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression
                 }
             }
         }
+
+        private static void UndoRgb96Bit(Span<byte> pixelBytes, int width, bool isBigEndian)
+        {
+            int rowBytesCount = width * 12;
+            int height = pixelBytes.Length / rowBytesCount;
+            if (isBigEndian)
+            {
+                for (int y = 0; y < height; y++)
+                {
+                    int offset = 0;
+                    Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
+                    uint r = TiffUtils.ConvertToUIntBigEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+                    uint g = TiffUtils.ConvertToUIntBigEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+                    uint b = TiffUtils.ConvertToUIntBigEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+
+                    for (int x = 1; x < width; x++)
+                    {
+                        Span<byte> rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaR = TiffUtils.ConvertToUIntBigEndian(rowSpan);
+                        r += deltaR;
+                        BinaryPrimitives.WriteUInt32BigEndian(rowSpan, r);
+                        offset += 4;
+
+                        rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaG = TiffUtils.ConvertToUIntBigEndian(rowSpan);
+                        g += deltaG;
+                        BinaryPrimitives.WriteUInt32BigEndian(rowSpan, g);
+                        offset += 4;
+
+                        rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaB = TiffUtils.ConvertToUIntBigEndian(rowSpan);
+                        b += deltaB;
+                        BinaryPrimitives.WriteUInt32BigEndian(rowSpan, b);
+                        offset += 4;
+                    }
+                }
+            }
+            else
+            {
+                for (int y = 0; y < height; y++)
+                {
+                    int offset = 0;
+                    Span<byte> rowBytes = pixelBytes.Slice(y * rowBytesCount, rowBytesCount);
+                    uint r = TiffUtils.ConvertToUIntLittleEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+                    uint g = TiffUtils.ConvertToUIntLittleEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+                    uint b = TiffUtils.ConvertToUIntLittleEndian(rowBytes.Slice(offset, 4));
+                    offset += 4;
+
+                    for (int x = 1; x < width; x++)
+                    {
+                        Span<byte> rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaR = TiffUtils.ConvertToUIntLittleEndian(rowSpan);
+                        r += deltaR;
+                        BinaryPrimitives.WriteUInt32LittleEndian(rowSpan, r);
+                        offset += 4;
+
+                        rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaG = TiffUtils.ConvertToUIntLittleEndian(rowSpan);
+                        g += deltaG;
+                        BinaryPrimitives.WriteUInt32LittleEndian(rowSpan, g);
+                        offset += 4;
+
+                        rowSpan = rowBytes.Slice(offset, 4);
+                        uint deltaB = TiffUtils.ConvertToUIntLittleEndian(rowSpan);
+                        b += deltaB;
+                        BinaryPrimitives.WriteUInt32LittleEndian(rowSpan, b);
+                        offset += 4;
+                    }
+                }
+            }
+        }
     }
 }

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

@@ -260,6 +260,17 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             image.DebugSave(provider);
         }
 
+        [Theory]
+        [WithFile(FlowerRgb323232PredictorBigEndian, PixelTypes.Rgba32)]
+        [WithFile(FlowerRgb323232PredictorLittleEndian, PixelTypes.Rgba32)]
+        public void TiffDecoder_CanDecode_96Bit_WithPredictor<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            // Note: because the MagickReferenceDecoder fails to load the image, we only debug save them.
+            using Image<TPixel> image = provider.GetImage();
+            image.DebugSave(provider);
+        }
+
         [Theory]
         [WithFile(GrayscaleDeflateMultistrip, PixelTypes.Rgba32)]
         [WithFile(RgbDeflateMultistrip, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -567,6 +567,8 @@ namespace SixLabors.ImageSharp.Tests
             public const string FlowerRgb323232ContiguousLittleEndian = "Tiff/flower-rgb-contig-32_lsb.tiff";
             public const string FlowerRgb323232Planar = "Tiff/flower-rgb-planar-32.tiff";
             public const string FlowerRgb323232PlanarLittleEndian = "Tiff/flower-rgb-planar-32_lsb.tiff";
+            public const string FlowerRgb323232PredictorBigEndian = "Tiff/flower-rgb-contig-32_msb_zip_predictor.tiff";
+            public const string FlowerRgb323232PredictorLittleEndian = "Tiff/flower-rgb-contig-32_lsb_zip_predictor.tiff";
             public const string FlowerRgb242424Planar = "Tiff/flower-rgb-planar-24.tiff";
             public const string FlowerRgb242424PlanarLittleEndian = "Tiff/flower-rgb-planar-24_lsb.tiff";
             public const string FlowerRgb242424Contiguous = "Tiff/flower-rgb-contig-24.tiff";

tests/Images/Input/Tiff/flower-rgb-contig-32_lsb_zip_predictor.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3ed60ad91ea70db01789f9dd37745d8a5ab86f72b98637cf2007b4e28a71976f
+size 37632

tests/Images/Input/Tiff/flower-rgb-contig-32_msb_zip_predictor.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1086c2ec568c5c3c2b08fcc66691fab017eb6fad109373a1dadd2e12fae86bc8
+size 37630