SixLabors · brianpopow · Jan 15, 2024 · Jan 8, 2024 · Jan 11, 2024 · Jan 13, 2024
diff --git a/src/ImageSharp/Formats/Tga/TgaDecoderCore.cs b/src/ImageSharp/Formats/Tga/TgaDecoderCore.cs
@@ -937,7 +937,9 @@ private TgaImageOrigin ReadFileHeader(BufferedReadStream stream)
        this.tgaMetadata = this.metadata.GetTgaMetadata();
        this.tgaMetadata.BitsPerPixel = (TgaBitsPerPixel)this.fileHeader.PixelDepth;

-        int alphaBits = this.fileHeader.ImageDescriptor & 0xf;
+        // TrueColor images with 32 bits per pixel are assumed to always have 8 bit alpha channel,
+        // because some encoders do not set correctly the alpha bits in the image descriptor.
+        int alphaBits = this.IsTrueColor32BitPerPixel(this.tgaMetadata.BitsPerPixel) ? 8 : this.fileHeader.ImageDescriptor & 0xf;
        if (alphaBits is not 0 and not 1 and not 8)
        {
            TgaThrowHelper.ThrowInvalidImageContentException("Invalid alpha channel bits");
@@ -949,4 +951,8 @@ private TgaImageOrigin ReadFileHeader(BufferedReadStream stream)
        // Bits 4 and 5 describe the image origin.
        return (TgaImageOrigin)((this.fileHeader.ImageDescriptor & 0x30) >> 4);
    }
+
+    private bool IsTrueColor32BitPerPixel(TgaBitsPerPixel bitsPerPixel) => bitsPerPixel == TgaBitsPerPixel.Pixel32 &&
+                                                                           (this.fileHeader.ImageType == TgaImageType.TrueColor ||
+                                                                            this.fileHeader.ImageType == TgaImageType.RleTrueColor);
 }
diff --git a/src/ImageSharp/Formats/Tga/TgaFileHeader.cs b/src/ImageSharp/Formats/Tga/TgaFileHeader.cs
@@ -131,10 +131,7 @@ public TgaFileHeader(
    /// </summary>
    public byte ImageDescriptor { get; }

-    public static TgaFileHeader Parse(Span<byte> data)
-    {
-        return MemoryMarshal.Cast<byte, TgaFileHeader>(data)[0];
-    }
+    public static TgaFileHeader Parse(Span<byte> data) => MemoryMarshal.Cast<byte, TgaFileHeader>(data)[0];

    public void WriteTo(Span<byte> buffer)
    {

diff --git a/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.

-using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics.X86;
 using Microsoft.DotNet.RemoteExecutor;
 using SixLabors.ImageSharp.Formats;
@@ -724,10 +723,8 @@ public void TgaDecoder_CanDecode_WhenAlphaBitsNotSet<TPixel>(TestImageProvider<T
    {
        using (Image<TPixel> image = provider.GetImage(TgaDecoder.Instance))
        {
-            // Using here the reference output instead of the the reference decoder,
-            // because the reference decoder does not ignore the alpha data here.
            image.DebugSave(provider);
-            image.CompareToReferenceOutput(ImageComparer.Exact, provider);
+            ImageComparingUtils.CompareWithReferenceDecoder(provider, image);
        }
    }

@@ -771,6 +768,19 @@ public void TgaDecoder_Decode_Resize<TPixel>(TestImageProvider<TPixel> provider)
            appendPixelTypeToFileName: false);
    }

+    // https://github.com/SixLabors/ImageSharp/issues/2629
+    [Theory]
+    [WithFile(Issue2629, PixelTypes.Rgba32)]
+    public void TgaDecoder_CanDecode_Issue2629<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using (Image<TPixel> image = provider.GetImage(TgaDecoder.Instance))
+        {
+            image.DebugSave(provider);
+            ImageComparingUtils.CompareWithReferenceDecoder(provider, image);
+        }
+    }
+
    [Theory]
    [WithFile(Bit16BottomLeft, PixelTypes.Rgba32)]
    [WithFile(Bit24BottomLeft, PixelTypes.Rgba32)]

diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
@@ -617,6 +617,8 @@ public static class Tga

        public const string Github_RLE_legacy = "Tga/Github_RLE_legacy.tga";
        public const string WhiteStripesPattern = "Tga/whitestripes.png";
+
+        public const string Issue2629 = "Tga/issues/Issue2629.tga";
    }

    public static class Webp

diff --git a/...derTests/TgaDecoder_CanDecode_WhenAlphaBitsNotSet_Rgba32_32bit_no_alphabits.png b/...derTests/TgaDecoder_CanDecode_WhenAlphaBitsNotSet_Rgba32_32bit_no_alphabits.png
diff --git a/...ests/TgaDecoder_CanDecode_WhenAlphaBitsNotSet_Rgba32_32bit_rle_no_alphabits.png b/...ests/TgaDecoder_CanDecode_WhenAlphaBitsNotSet_Rgba32_32bit_rle_no_alphabits.png
diff --git a/tests/Images/Input/Tga/32bit_no_alphabits.tga b/tests/Images/Input/Tga/32bit_no_alphabits.tga
diff --git a/tests/Images/Input/Tga/32bit_rle_no_alphabits.tga b/tests/Images/Input/Tga/32bit_rle_no_alphabits.tga
diff --git a/tests/Images/Input/Tga/issues/Issue2629.tga b/tests/Images/Input/Tga/issues/Issue2629.tga