Preserve color profile when encoding webp images

src/ImageSharp/Formats/Webp/BitWriter/BitWriterBase.cs

@@ -5,6 +5,7 @@
 using System.Buffers.Binary;
 using System.IO;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
+using SixLabors.ImageSharp.Metadata.Profiles.Icc;
 using SixLabors.ImageSharp.Metadata.Profiles.Xmp;
 
 namespace SixLabors.ImageSharp.Formats.Webp.BitWriter
@@ -97,7 +98,7 @@ protected void WriteRiffHeader(Stream stream, uint riffSize)
         }
 
         /// <summary>
-        /// Calculates the chunk size of EXIF or XMP metadata.
+        /// Calculates the chunk size of EXIF, XMP or ICCP metadata.
         /// </summary>
         /// <param name="metadataBytes">The metadata profile bytes.</param>
         /// <returns>The metadata chunk size in bytes.</returns>
@@ -178,16 +179,41 @@ protected void WriteAlphaChunk(Stream stream, Span<byte> dataBytes, bool alphaDa
             }
         }
 
+        /// <summary>
+        /// Writes the color profile to the stream.
+        /// </summary>
+        /// <param name="stream">The stream to write to.</param>
+        /// <param name="iccProfileBytes">The color profile bytes.</param>
+        protected void WriteColorProfile(Stream stream, byte[] iccProfileBytes)
+        {
+            uint size = (uint)iccProfileBytes.Length;
+
+            Span<byte> buf = this.scratchBuffer.AsSpan(0, 4);
+            BinaryPrimitives.WriteUInt32BigEndian(buf, (uint)WebpChunkType.Iccp);
+            stream.Write(buf);
+            BinaryPrimitives.WriteUInt32LittleEndian(buf, size);
+            stream.Write(buf);
+
+            stream.Write(iccProfileBytes);
+
+            // Add padding byte if needed.
+            if ((size & 1) == 1)
+            {
+                stream.WriteByte(0);
+            }
+        }
+
         /// <summary>
         /// Writes a VP8X header to the stream.
         /// </summary>
         /// <param name="stream">The stream to write to.</param>
         /// <param name="exifProfile">A exif profile or null, if it does not exist.</param>
         /// <param name="xmpProfile">A XMP profile or null, if it does not exist.</param>
+        /// <param name="iccProfileBytes">The color profile bytes.</param>
         /// <param name="width">The width of the image.</param>
         /// <param name="height">The height of the image.</param>
         /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
-        protected void WriteVp8XHeader(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, uint width, uint height, bool hasAlpha)
+        protected void WriteVp8XHeader(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, byte[] iccProfileBytes, uint width, uint height, bool hasAlpha)
         {
             if (width > MaxDimension || height > MaxDimension)
             {
@@ -219,6 +245,12 @@ protected void WriteVp8XHeader(Stream stream, ExifProfile exifProfile, XmpProfil
                 flags |= 16;
             }
 
+            if (iccProfileBytes != null)
+            {
+                // Set iccp flag.
+                flags |= 32;
+            }
+
             Span<byte> buf = this.scratchBuffer.AsSpan(0, 4);
             stream.Write(WebpConstants.Vp8XMagicBytes);
             BinaryPrimitives.WriteUInt32LittleEndian(buf, WebpConstants.Vp8XChunkSize);

src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using SixLabors.ImageSharp.Formats.Webp.Lossy;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
+using SixLabors.ImageSharp.Metadata.Profiles.Icc;
 using SixLabors.ImageSharp.Metadata.Profiles.Xmp;
 
 namespace SixLabors.ImageSharp.Formats.Webp.BitWriter
@@ -406,6 +407,7 @@ private void Flush()
         /// <param name="stream">The stream to write to.</param>
         /// <param name="exifProfile">The exif profile.</param>
         /// <param name="xmpProfile">The XMP profile.</param>
+        /// <param name="iccProfile">The color profile.</param>
         /// <param name="width">The width of the image.</param>
         /// <param name="height">The height of the image.</param>
         /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
@@ -415,6 +417,7 @@ public void WriteEncodedImageToStream(
             Stream stream,
             ExifProfile exifProfile,
             XmpProfile xmpProfile,
+            IccProfile iccProfile,
             uint width,
             uint height,
             bool hasAlpha,
@@ -424,6 +427,7 @@ public void WriteEncodedImageToStream(
             bool isVp8X = false;
             byte[] exifBytes = null;
             byte[] xmpBytes = null;
+            byte[] iccProfileBytes = null;
             uint riffSize = 0;
             if (exifProfile != null)
             {
@@ -439,6 +443,13 @@ public void WriteEncodedImageToStream(
                 riffSize += this.MetadataChunkSize(xmpBytes);
             }
 
+            if (iccProfile != null)
+            {
+                isVp8X = true;
+                iccProfileBytes = iccProfile.ToByteArray();
+                riffSize += this.MetadataChunkSize(iccProfileBytes);
+            }
+
             if (hasAlpha)
             {
                 isVp8X = true;
@@ -457,20 +468,20 @@ public void WriteEncodedImageToStream(
 
             var bitWriterPartZero = new Vp8BitWriter(expectedSize);
 
-            // Partition #0 with header and partition sizes
+            // Partition #0 with header and partition sizes.
             uint size0 = this.GeneratePartition0(bitWriterPartZero);
 
             uint vp8Size = WebpConstants.Vp8FrameHeaderSize + size0;
             vp8Size += numBytes;
             uint pad = vp8Size & 1;
             vp8Size += pad;
 
-            // Compute RIFF size
+            // Compute RIFF size.
             // At the minimum it is: "WEBPVP8 nnnn" + VP8 data size.
             riffSize += WebpConstants.TagSize + WebpConstants.ChunkHeaderSize + vp8Size;
 
             // Emit headers and partition #0
-            this.WriteWebpHeaders(stream, size0, vp8Size, riffSize, isVp8X, width, height, exifProfile, xmpProfile, hasAlpha, alphaData, alphaDataIsCompressed);
+            this.WriteWebpHeaders(stream, size0, vp8Size, riffSize, isVp8X, width, height, exifProfile, xmpProfile, iccProfileBytes, hasAlpha, alphaData, alphaDataIsCompressed);
             bitWriterPartZero.WriteToStream(stream);
 
             // Write the encoded image to the stream.
@@ -668,6 +679,7 @@ private void WriteWebpHeaders(
             uint height,
             ExifProfile exifProfile,
             XmpProfile xmpProfile,
+            byte[] iccProfileBytes,
             bool hasAlpha,
             Span<byte> alphaData,
             bool alphaDataIsCompressed)
@@ -677,7 +689,13 @@ private void WriteWebpHeaders(
             // Write VP8X, header if necessary.
             if (isVp8X)
             {
-                this.WriteVp8XHeader(stream, exifProfile, xmpProfile, width, height, hasAlpha);
+                this.WriteVp8XHeader(stream, exifProfile, xmpProfile, iccProfileBytes, width, height, hasAlpha);
+
+                if (iccProfileBytes != null)
+                {
+                    this.WriteColorProfile(stream, iccProfileBytes);
+                }
+
                 if (hasAlpha)
                 {
                     this.WriteAlphaChunk(stream, alphaData, alphaDataIsCompressed);

src/ImageSharp/Formats/Webp/BitWriter/Vp8LBitWriter.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using SixLabors.ImageSharp.Formats.Webp.Lossless;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
+using SixLabors.ImageSharp.Metadata.Profiles.Icc;
 using SixLabors.ImageSharp.Metadata.Profiles.Xmp;
 
 namespace SixLabors.ImageSharp.Formats.Webp.BitWriter
@@ -134,31 +135,43 @@ public override void Finish()
         /// <param name="stream">The stream to write to.</param>
         /// <param name="exifProfile">The exif profile.</param>
         /// <param name="xmpProfile">The XMP profile.</param>
+        /// <param name="iccProfile">The color profile.</param>
         /// <param name="width">The width of the image.</param>
         /// <param name="height">The height of the image.</param>
         /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
-        public void WriteEncodedImageToStream(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, uint width, uint height, bool hasAlpha)
+        public void WriteEncodedImageToStream(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, IccProfile iccProfile, uint width, uint height, bool hasAlpha)
         {
             bool isVp8X = false;
             byte[] exifBytes = null;
             byte[] xmpBytes = null;
+            byte[] iccBytes = null;
             uint riffSize = 0;
             if (exifProfile != null)
             {
                 isVp8X = true;
-                riffSize += ExtendedFileChunkSize;
                 exifBytes = exifProfile.ToByteArray();
                 riffSize += this.MetadataChunkSize(exifBytes);
             }
 
             if (xmpProfile != null)
             {
                 isVp8X = true;
-                riffSize += ExtendedFileChunkSize;
                 xmpBytes = xmpProfile.Data;
                 riffSize += this.MetadataChunkSize(xmpBytes);
             }
 
+            if (iccProfile != null)
+            {
+                isVp8X = true;
+                iccBytes = iccProfile.ToByteArray();
+                riffSize += this.MetadataChunkSize(iccBytes);
+            }
+
+            if (isVp8X)
+            {
+                riffSize += ExtendedFileChunkSize;
+            }
+
             this.Finish();
             uint size = (uint)this.NumBytes();
             size++; // One byte extra for the VP8L signature.
@@ -171,7 +184,12 @@ public void WriteEncodedImageToStream(Stream stream, ExifProfile exifProfile, Xm
             // Write VP8X, header if necessary.
             if (isVp8X)
             {
-                this.WriteVp8XHeader(stream, exifProfile, xmpProfile, width, height, hasAlpha);
+                this.WriteVp8XHeader(stream, exifProfile, xmpProfile, iccBytes, width, height, hasAlpha);
+
+                if (iccBytes != null)
+                {
+                    this.WriteColorProfile(stream, iccBytes);
+                }
             }
 
             // Write magic bytes indicating its a lossless webp.

src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs

@@ -255,7 +255,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream)
             this.EncodeStream(image);
 
             // Write bytes from the bitwriter buffer to the stream.
-            this.bitWriter.WriteEncodedImageToStream(stream, metadata.ExifProfile, metadata.XmpProfile, (uint)width, (uint)height, hasAlpha);
+            this.bitWriter.WriteEncodedImageToStream(stream, metadata.ExifProfile, metadata.XmpProfile, metadata.IccProfile, (uint)width, (uint)height, hasAlpha);
         }
 
         /// <summary>

src/ImageSharp/Formats/Webp/Lossy/Vp8Encoder.cs

@@ -378,6 +378,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream)
                 stream,
                 metadata.ExifProfile,
                 metadata.XmpProfile,
+                metadata.IccProfile,
                 (uint)width,
                 (uint)height,
                 hasAlpha,

tests/ImageSharp.Tests/Formats/WebP/WebpMetaDataTests.cs

@@ -152,6 +152,37 @@ public void EncodeLosslessWebp_PreservesExif<TPixel>(TestImageProvider<TPixel> p
             Assert.Equal(expectedExif.Values.Count, actualExif.Values.Count);
         }
 
+        [Theory]
+        [WithFile(TestImages.Webp.Lossy.WithIccp, PixelTypes.Rgba32, WebpFileFormatType.Lossless)]
+        [WithFile(TestImages.Webp.Lossy.WithIccp, PixelTypes.Rgba32, WebpFileFormatType.Lossy)]
+        public void Encode_PreservesColorProfile<TPixel>(TestImageProvider<TPixel> provider, WebpFileFormatType fileFormat)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> input = provider.GetImage(new WebpDecoder()))
+            {
+                ImageSharp.Metadata.Profiles.Icc.IccProfile expectedProfile = input.Metadata.IccProfile;
+                byte[] expectedProfileBytes = expectedProfile.ToByteArray();
+
+                using (var memStream = new MemoryStream())
+                {
+                    input.Save(memStream, new WebpEncoder()
+                    {
+                        FileFormat = fileFormat
+                    });
+
+                    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(TestImages.Webp.Lossy.WithExifNotEnoughData, PixelTypes.Rgba32)]
         public void WebpDecoder_IgnoresInvalidExifChunk<TPixel>(TestImageProvider<TPixel> provider)