Add support for decoding 32bit per channel color tiff with contiguous pixel data

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb242424TiffColor{TPixel}.cs

@@ -9,7 +9,7 @@ using SixLabors.ImageSharp.PixelFormats;
 namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 {
     /// <summary>
-    /// Implements the 'RGB' photometric interpretation with 16 bits for each channel.
+    /// Implements the 'RGB' photometric interpretation with 24 bits for each channel.
     /// </summary>
     internal class Rgb242424TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb323232TiffColor{TPixel}.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// Implements the 'RGB' photometric interpretation with 32 bits for each channel.
+    /// </summary>
+    internal class Rgb323232TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly bool isBigEndian;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Rgb323232TiffColor{TPixel}" /> class.
+        /// </summary>
+        /// <param name="isBigEndian">if set to <c>true</c> decodes the pixel data as big endian, otherwise as little endian.</param>
+        public Rgb323232TiffColor(bool isBigEndian) => this.isBigEndian = isBigEndian;
+
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        {
+            // Note: due to an issue with netcore 2.1 and default values and unpredictable behavior with those,
+            // we define our own defaults as a workaround. See: https://github.com/dotnet/runtime/issues/55623
+            var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
+            int offset = 0;
+
+            for (int y = top; y < top + height; y++)
+            {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+
+                if (this.isBigEndian)
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ulong r = TiffUtils.ConvertToUIntBigEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        ulong g = TiffUtils.ConvertToUIntBigEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        ulong b = TiffUtils.ConvertToUIntBigEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        pixelRow[x] = TiffUtils.ColorScaleTo32Bit(r, g, b, color);
+                    }
+                }
+                else
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ulong r = TiffUtils.ConvertToUIntLittleEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        ulong g = TiffUtils.ConvertToUIntLittleEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        ulong b = TiffUtils.ConvertToUIntLittleEndian(data.Slice(offset, 4));
+                        offset += 4;
+
+                        pixelRow[x] = TiffUtils.ColorScaleTo32Bit(r, g, b, color);
+                    }
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffColorDecoderFactory{TPixel}.cs

@@ -166,6 +166,16 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
                     return new Rgb242424TiffColor<TPixel>(isBigEndian: byteOrder == ByteOrder.BigEndian);
 
+                case TiffColorType.Rgb323232:
+                    DebugGuard.IsTrue(
+                        bitsPerSample.Channels == 3
+                        && bitsPerSample.Channel2 == 32
+                        && bitsPerSample.Channel1 == 32
+                        && bitsPerSample.Channel0 == 32,
+                        "bitsPerSample");
+                    DebugGuard.IsTrue(colorMap == null, "colorMap");
+                    return new Rgb323232TiffColor<TPixel>(isBigEndian: byteOrder == ByteOrder.BigEndian);
+
                 case TiffColorType.PaletteColor:
                     DebugGuard.NotNull(colorMap, "colorMap");
                     return new PaletteTiffColor<TPixel>(bitsPerSample, colorMap);

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

@@ -128,6 +128,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// </summary>
         Rgb242424,
 
+        /// <summary>
+        /// RGB color image with 32 bits for each channel.
+        /// </summary>
+        Rgb323232,
+
         /// <summary>
         /// RGB Full Color. Planar configuration of data.
         /// </summary>

src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs

@@ -230,6 +230,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                         ushort bitsPerChannel = options.BitsPerSample.Channel0;
                         switch (bitsPerChannel)
                         {
+                            case 32:
+                                options.ColorType = TiffColorType.Rgb323232;
+                                break;
+
                             case 24:
                                 options.ColorType = TiffColorType.Rgb242424;
                                 break;

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

@@ -63,6 +63,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Utils
             return color;
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static TPixel ColorScaleTo32Bit<TPixel>(ulong r, ulong g, ulong b, TPixel color)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            var colorVector = new Vector4(r * Scale32Bit, g * Scale32Bit, b * Scale32Bit, 1.0f);
+            color.FromVector4(colorVector);
+            return color;
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static TPixel ColorFromL16<TPixel>(L16 l16, ushort intensity, TPixel color)
             where TPixel : unmanaged, IPixel<TPixel>

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

@@ -199,6 +199,11 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
         public void TiffDecoder_CanDecode_72Bit<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
 
+        [Theory]
+        [WithFile(FlowerRgb323232Contiguous, PixelTypes.Rgba32)]
+        public void TiffDecoder_CanDecode_96Bit<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
+
         [Theory]
         [WithFile(GrayscaleDeflateMultistrip, PixelTypes.Rgba32)]
         [WithFile(RgbDeflateMultistrip, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -561,6 +561,7 @@ namespace SixLabors.ImageSharp.Tests
             public const string RgbPalette = "Tiff/rgb_palette.tiff";
             public const string Rgb4BitPalette = "Tiff/bike_colorpalette_4bit.tiff";
             public const string RgbPaletteDeflate = "Tiff/rgb_palette_deflate.tiff";
+            public const string FlowerRgb323232Contiguous = "Tiff/flower-rgb-contig-32.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.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d7b9da8ec44da84fc89aed1ad221a5eb130a1f233a1ff8a4a15b41898a0e364f
+size 38027