Add color profile tests

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -163,7 +163,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
             this.WriteBitmapFileHeader(stream, infoHeaderSize, colorPaletteSize, iccProfileSize, infoHeader, buffer);
             this.WriteBitmapInfoHeader(stream, infoHeader, buffer, infoHeaderSize);
             this.WriteImage(stream, image.Frames.RootFrame);
-            this.WriteColorProfile(stream, metadata, buffer);
+            this.WriteColorProfile(stream, iccProfileData, buffer);
 
             stream.Flush();
         }
@@ -246,14 +246,15 @@ private BmpInfoHeader CreateBmpInfoHeader(int width, int height, int infoHeaderS
         /// Writes the color profile to the stream.
         /// </summary>
         /// <param name="stream">The stream to write to.</param>
-        /// <param name="metadata">The metadata.</param>
+        /// <param name="iccProfileData">The color profile data.</param>
         /// <param name="buffer">The buffer.</param>
-        private void WriteColorProfile(Stream stream, ImageMetadata metadata, Span<byte> buffer)
+        private void WriteColorProfile(Stream stream, byte[] iccProfileData, Span<byte> buffer)
         {
-            if (metadata.IccProfile != null)
+            if (iccProfileData != null)
             {
-                int streamPositionAfterImageData = (int)stream.Position;
-                stream.Write(metadata.IccProfile.ToByteArray());
+                // The offset, in bytes, from the beginning of the BITMAPV5HEADER structure to the start of the profile data.
+                int streamPositionAfterImageData = (int)stream.Position - BmpFileHeader.Size;
+                stream.Write(iccProfileData);
                 BinaryPrimitives.WriteInt32LittleEndian(buffer, streamPositionAfterImageData);
                 stream.Position = BmpFileHeader.Size + 112;
                 stream.Write(buffer.Slice(0, 4));

tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs

@@ -29,10 +29,10 @@ public class BmpDecoderTests
 
         public static readonly string[] BitfieldsBmpFiles = BitFields;
 
-        private static BmpDecoder BmpDecoder => new BmpDecoder();
+        private static BmpDecoder BmpDecoder => new();
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-        new TheoryData<string, int, int, PixelResolutionUnit>
+        new()
         {
             { Car, 3780, 3780, PixelResolutionUnit.PixelsPerMeter },
             { V5Header, 3780, 3780, PixelResolutionUnit.PixelsPerMeter },

tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs

@@ -301,6 +301,33 @@ public void Encode_8BitColor_WithOctreeQuantizer<TPixel>(TestImageProvider<TPixe
         public void Encode_PreservesAlpha<TPixel>(TestImageProvider<TPixel> provider, BmpBitsPerPixel bitsPerPixel)
             where TPixel : unmanaged, IPixel<TPixel> => TestBmpEncoderCore(provider, bitsPerPixel, supportTransparency: true);
 
+        [Theory]
+        [WithFile(IccProfile, PixelTypes.Rgba32)]
+        public void Encode_PreservesColorProfile<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> input = provider.GetImage(new BmpDecoder()))
+            {
+                ImageSharp.Metadata.Profiles.Icc.IccProfile expectedProfile = input.Metadata.IccProfile;
+                byte[] expectedProfileBytes = expectedProfile.ToByteArray();
+
+                using (var memStream = new MemoryStream())
+                {
+                    input.Save(memStream, new BmpEncoder());
+
+                    memStream.Position = 0;
+                    using (var output = Image.Load<Rgba32>(memStream))
+                    {
+                        ImageSharp.Metadata.Profiles.Icc.IccProfile actualProfile = output.Metadata.IccProfile;
+                        byte[] actualProfileBytes = actualProfile.ToByteArray();
+
+                        Assert.NotNull(actualProfile);
+                        Assert.Equal(expectedProfileBytes, actualProfileBytes);
+                    }
+                }
+            }
+        }
+
         [Theory]
         [WithFile(Car, PixelTypes.Rgba32, BmpBitsPerPixel.Pixel32)]
         [WithFile(V5Header, PixelTypes.Rgba32, BmpBitsPerPixel.Pixel32)]

tests/ImageSharp.Tests/Formats/Bmp/BmpMetadataTests.cs

@@ -3,7 +3,7 @@
 
 using System.IO;
 using SixLabors.ImageSharp.Formats.Bmp;
-
+using SixLabors.ImageSharp.PixelFormats;
 using Xunit;
 using static SixLabors.ImageSharp.Tests.TestImages.Bmp;
 
@@ -47,5 +47,19 @@ public void Identify_DetectsCorrectBitmapInfoHeaderType(string imagePath, BmpInf
                 Assert.Equal(expectedInfoHeaderType, bitmapMetadata.InfoHeaderType);
             }
         }
+
+        [Theory]
+        [WithFile(IccProfile, PixelTypes.Rgba32)]
+        public void Decoder_CanReadColorProfile<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage(new BmpDecoder()))
+            {
+                ImageSharp.Metadata.ImageMetadata metaData = image.Metadata;
+                Assert.NotNull(metaData);
+                Assert.NotNull(metaData.IccProfile);
+                Assert.Equal(16, metaData.IccProfile.Entries.Length);
+            }
+        }
     }
 }

tests/ImageSharp.Tests/TestImages.cs

@@ -379,6 +379,7 @@ public static class Bmp
             public const string Rgb24jpeg = "Bmp/rgb24jpeg.bmp";
             public const string Rgb24png = "Bmp/rgb24png.bmp";
             public const string Rgba32v4 = "Bmp/rgba32v4.bmp";
+            public const string IccProfile = "Bmp/BMP_v5_with_ICC_2.bmp";
 
             // Bitmap images with compression type BITFIELDS.
             public const string Rgb32bfdef = "Bmp/rgb32bfdef.bmp";