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Merge pull request #2110 from SixLabors/bp/png-iccp 

Preserve color profile when encoding PNG images
pull/2135/head
Brian Popow 4 years ago
committed by GitHub
parent
fcac74b4b7 a0e38c87b0
commit
5634228f59
No known key found for this signature in database GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 166 additions and 46 deletions
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  1. 101
      src/ImageSharp/Formats/Png/PngDecoderCore.cs
  2. 81
      src/ImageSharp/Formats/Png/PngEncoderCore.cs
  3. 1
      tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.Chunks.cs
  4. 29
      tests/ImageSharp.Tests/Formats/Png/PngMetadataTests.cs

101
src/ImageSharp/Formats/Png/PngDecoderCore.cs
View File

@ -19,6 +19,7 @@ using SixLabors.ImageSharp.IO;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.Metadata;
using SixLabors.ImageSharp.Metadata.Profiles.Exif;
using SixLabors.ImageSharp.Metadata.Profiles.Icc;
using SixLabors.ImageSharp.Metadata.Profiles.Xmp;
using SixLabors.ImageSharp.PixelFormats;
@ -205,6 +206,9 @@ namespace SixLabors.ImageSharp.Formats.Png
this.MergeOrSetExifProfile(metadata, new ExifProfile(exifData), replaceExistingKeys: true);
}
break;
case PngChunkType.EmbeddedColorProfile:
this.ReadColorProfileChunk(metadata, chunk.Data.GetSpan());
break;
case PngChunkType.End:
goto EOF;
@ -1174,6 +1178,76 @@ namespace SixLabors.ImageSharp.Formats.Png
return true;
}
/// <summary>
/// Reads the color profile chunk. The data is stored similar to the zTXt chunk.
/// </summary>
/// <param name="metadata">The metadata.</param>
/// <param name="data">The bytes containing the profile.</param>
private void ReadColorProfileChunk(ImageMetadata metadata, ReadOnlySpan<byte> data)
{
int zeroIndex = data.IndexOf((byte)0);
if (zeroIndex is < PngConstants.MinTextKeywordLength or > PngConstants.MaxTextKeywordLength)
{
return;
}
byte compressionMethod = data[zeroIndex + 1];
if (compressionMethod != 0)
{
// Only compression method 0 is supported (zlib datastream with deflate compression).
return;
}
ReadOnlySpan<byte> keywordBytes = data.Slice(0, zeroIndex);
if (!this.TryReadTextKeyword(keywordBytes, out string name))
{
return;
}
ReadOnlySpan<byte> compressedData = data.Slice(zeroIndex + 2);
if (this.TryUncompressZlibData(compressedData, out byte[] iccpProfileBytes))
{
metadata.IccProfile = new IccProfile(iccpProfileBytes);
}
}
/// <summary>
/// Tries to un-compress zlib compressed data.
/// </summary>
/// <param name="compressedData">The compressed data.</param>
/// <param name="uncompressedBytesArray">The uncompressed bytes array.</param>
/// <returns>True, if de-compressing was successful.</returns>
private unsafe bool TryUncompressZlibData(ReadOnlySpan<byte> compressedData, out byte[] uncompressedBytesArray)
{
fixed (byte* compressedDataBase = compressedData)
{
using (IMemoryOwner<byte> destBuffer = this.memoryAllocator.Allocate<byte>(this.Configuration.StreamProcessingBufferSize))
using (var memoryStreamOutput = new MemoryStream(compressedData.Length))
using (var memoryStreamInput = new UnmanagedMemoryStream(compressedDataBase, compressedData.Length))
using (var bufferedStream = new BufferedReadStream(this.Configuration, memoryStreamInput))
using (var inflateStream = new ZlibInflateStream(bufferedStream))
{
Span<byte> destUncompressedData = destBuffer.GetSpan();
if (!inflateStream.AllocateNewBytes(compressedData.Length, false))
{
uncompressedBytesArray = Array.Empty<byte>();
return false;
}
int bytesRead = inflateStream.CompressedStream.Read(destUncompressedData, 0, destUncompressedData.Length);
while (bytesRead != 0)
{
memoryStreamOutput.Write(destUncompressedData.Slice(0, bytesRead));
bytesRead = inflateStream.CompressedStream.Read(destUncompressedData, 0, destUncompressedData.Length);
}
uncompressedBytesArray = memoryStreamOutput.ToArray();
return true;
}
}
}
/// <summary>
/// Compares two ReadOnlySpan&lt;char&gt;s in a case-insensitive method.
/// This is only needed because older frameworks are missing the extension method.
@ -1306,7 +1380,7 @@ namespace SixLabors.ImageSharp.Formats.Png
}
else if (this.IsXmpTextData(keywordBytes))
{
XmpProfile xmpProfile = new XmpProfile(data.Slice(dataStartIdx).ToArray());
var xmpProfile = new XmpProfile(data.Slice(dataStartIdx).ToArray());
metadata.XmpProfile = xmpProfile;
}
else
@ -1325,29 +1399,14 @@ namespace SixLabors.ImageSharp.Formats.Png
/// <returns>The <see cref="bool"/>.</returns>
private bool TryUncompressTextData(ReadOnlySpan<byte> compressedData, Encoding encoding, out string value)
{
using (var memoryStream = new MemoryStream(compressedData.ToArray()))
using (var bufferedStream = new BufferedReadStream(this.Configuration, memoryStream))
using (var inflateStream = new ZlibInflateStream(bufferedStream))
if (this.TryUncompressZlibData(compressedData, out byte[] uncompressedData))
{
if (!inflateStream.AllocateNewBytes(compressedData.Length, false))
{
value = null;
return false;
}
var uncompressedBytes = new List<byte>();
// Note: this uses a buffer which is only 4 bytes long to read the stream, maybe allocating a larger buffer makes sense here.
int bytesRead = inflateStream.CompressedStream.Read(this.buffer, 0, this.buffer.Length);
while (bytesRead != 0)
{
uncompressedBytes.AddRange(this.buffer.AsSpan(0, bytesRead).ToArray());
bytesRead = inflateStream.CompressedStream.Read(this.buffer, 0, this.buffer.Length);
}
value = encoding.GetString(uncompressedBytes.ToArray());
value = encoding.GetString(uncompressedData);
return true;
}
value = null;
return false;
}
/// <summary>

81
src/ImageSharp/Formats/Png/PngEncoderCore.cs
View File

@ -87,6 +87,11 @@ namespace SixLabors.ImageSharp.Formats.Png
/// </summary>
private IMemoryOwner<byte> currentScanline;
/// <summary>
/// The color profile name.
/// </summary>
private const string ColorProfileName = "ICC Profile";
/// <summary>
/// Initializes a new instance of the <see cref="PngEncoderCore" /> class.
/// </summary>
@ -134,6 +139,7 @@ namespace SixLabors.ImageSharp.Formats.Png
this.WriteHeaderChunk(stream);
this.WriteGammaChunk(stream);
this.WriteColorProfileChunk(stream, metadata);
this.WritePaletteChunk(stream, quantized);
this.WriteTransparencyChunk(stream, pngMetadata);
this.WritePhysicalChunk(stream, metadata);
@ -656,7 +662,7 @@ namespace SixLabors.ImageSharp.Formats.Png
}
/// <summary>
/// Writes an iTXT chunk, containing the XMP metdata to the stream, if such profile is present in the metadata.
/// Writes an iTXT chunk, containing the XMP metadata to the stream, if such profile is present in the metadata.
/// </summary>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
/// <param name="meta">The image metadata.</param>
@ -673,7 +679,7 @@ namespace SixLabors.ImageSharp.Formats.Png
return;
}
var xmpData = meta.XmpProfile.Data;
byte[] xmpData = meta.XmpProfile.Data;
if (xmpData.Length == 0)
{
@ -687,19 +693,49 @@ namespace SixLabors.ImageSharp.Formats.Png
PngConstants.XmpKeyword.CopyTo(payload);
int bytesWritten = PngConstants.XmpKeyword.Length;
// Write the iTxt header (all zeros in this case)
payload[bytesWritten++] = 0;
payload[bytesWritten++] = 0;
payload[bytesWritten++] = 0;
payload[bytesWritten++] = 0;
payload[bytesWritten++] = 0;
// Write the iTxt header (all zeros in this case).
Span<byte> iTxtHeader = payload.Slice(bytesWritten);
iTxtHeader[4] = 0;
iTxtHeader[3] = 0;
iTxtHeader[2] = 0;
iTxtHeader[1] = 0;
iTxtHeader[0] = 0;
bytesWritten += 5;
// And the XMP data itself
// And the XMP data itself.
xmpData.CopyTo(payload.Slice(bytesWritten));
this.WriteChunk(stream, PngChunkType.InternationalText, payload);
}
}
/// <summary>
/// Writes the color profile chunk.
/// </summary>
/// <param name="stream">The stream to write to.</param>
/// <param name="metaData">The image meta data.</param>
private void WriteColorProfileChunk(Stream stream, ImageMetadata metaData)
{
if (metaData.IccProfile is null)
{
return;
}
byte[] iccProfileBytes = metaData.IccProfile.ToByteArray();
byte[] compressedData = this.GetZlibCompressedBytes(iccProfileBytes);
int payloadLength = ColorProfileName.Length + compressedData.Length + 2;
using (IMemoryOwner<byte> owner = this.memoryAllocator.Allocate<byte>(payloadLength))
{
Span<byte> outputBytes = owner.GetSpan();
PngConstants.Encoding.GetBytes(ColorProfileName).CopyTo(outputBytes);
int bytesWritten = ColorProfileName.Length;
outputBytes[bytesWritten++] = 0; // Null separator.
outputBytes[bytesWritten++] = 0; // Compression.
compressedData.CopyTo(outputBytes.Slice(bytesWritten));
this.WriteChunk(stream, PngChunkType.EmbeddedColorProfile, outputBytes);
}
}
/// <summary>
/// Writes a text chunk to the stream. Can be either a tTXt, iTXt or zTXt chunk,
/// depending whether the text contains any latin characters or should be compressed.
@ -727,13 +763,12 @@ namespace SixLabors.ImageSharp.Formats.Png
}
}
if (hasUnicodeCharacters || (!string.IsNullOrWhiteSpace(textData.LanguageTag) ||
!string.IsNullOrWhiteSpace(textData.TranslatedKeyword)))
if (hasUnicodeCharacters || (!string.IsNullOrWhiteSpace(textData.LanguageTag) || !string.IsNullOrWhiteSpace(textData.TranslatedKeyword)))
{
// Write iTXt chunk.
byte[] keywordBytes = PngConstants.Encoding.GetBytes(textData.Keyword);
byte[] textBytes = textData.Value.Length > this.options.TextCompressionThreshold
? this.GetCompressedTextBytes(PngConstants.TranslatedEncoding.GetBytes(textData.Value))
? this.GetZlibCompressedBytes(PngConstants.TranslatedEncoding.GetBytes(textData.Value))
: PngConstants.TranslatedEncoding.GetBytes(textData.Value);
byte[] translatedKeyword = PngConstants.TranslatedEncoding.GetBytes(textData.TranslatedKeyword);
@ -772,18 +807,17 @@ namespace SixLabors.ImageSharp.Formats.Png
if (textData.Value.Length > this.options.TextCompressionThreshold)
{
// Write zTXt chunk.
byte[] compressedData =
this.GetCompressedTextBytes(PngConstants.Encoding.GetBytes(textData.Value));
byte[] compressedData = this.GetZlibCompressedBytes(PngConstants.Encoding.GetBytes(textData.Value));
int payloadLength = textData.Keyword.Length + compressedData.Length + 2;
using (IMemoryOwner<byte> owner = this.memoryAllocator.Allocate<byte>(payloadLength))
{
Span<byte> outputBytes = owner.GetSpan();
PngConstants.Encoding.GetBytes(textData.Keyword).CopyTo(outputBytes);
int bytesWritten = textData.Keyword.Length;
outputBytes[bytesWritten++] = 0;
outputBytes[bytesWritten++] = 0;
outputBytes[bytesWritten++] = 0; // Null separator.
outputBytes[bytesWritten++] = 0; // Compression.
compressedData.CopyTo(outputBytes.Slice(bytesWritten));
this.WriteChunk(stream, PngChunkType.CompressedText, outputBytes.ToArray());
this.WriteChunk(stream, PngChunkType.CompressedText, outputBytes);
}
}
else
@ -796,9 +830,8 @@ namespace SixLabors.ImageSharp.Formats.Png
PngConstants.Encoding.GetBytes(textData.Keyword).CopyTo(outputBytes);
int bytesWritten = textData.Keyword.Length;
outputBytes[bytesWritten++] = 0;
PngConstants.Encoding.GetBytes(textData.Value)
.CopyTo(outputBytes.Slice(bytesWritten));
this.WriteChunk(stream, PngChunkType.Text, outputBytes.ToArray());
PngConstants.Encoding.GetBytes(textData.Value).CopyTo(outputBytes.Slice(bytesWritten));
this.WriteChunk(stream, PngChunkType.Text, outputBytes);
}
}
}
@ -808,15 +841,15 @@ namespace SixLabors.ImageSharp.Formats.Png
/// <summary>
/// Compresses a given text using Zlib compression.
/// </summary>
/// <param name="textBytes">The text bytes to compress.</param>
/// <returns>The compressed text byte array.</returns>
private byte[] GetCompressedTextBytes(byte[] textBytes)
/// <param name="dataBytes">The bytes to compress.</param>
/// <returns>The compressed byte array.</returns>
private byte[] GetZlibCompressedBytes(byte[] dataBytes)
{
using (var memoryStream = new MemoryStream())
{
using (var deflateStream = new ZlibDeflateStream(this.memoryAllocator, memoryStream, this.options.CompressionLevel))
{
deflateStream.Write(textBytes);
deflateStream.Write(dataBytes);
}
return memoryStream.ToArray();

1
tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.Chunks.cs
View File

@ -302,6 +302,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
{
PngChunkType.Header,
PngChunkType.Gamma,
PngChunkType.EmbeddedColorProfile,
PngChunkType.Palette,
PngChunkType.InternationalText,
PngChunkType.Text,

29
tests/ImageSharp.Tests/Formats/Png/PngMetadataTests.cs
View File

@ -17,7 +17,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
public class PngMetadataTests
{
public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
new TheoryData<string, int, int, PixelResolutionUnit>
new()
{
{ TestImages.Png.Splash, 11810, 11810, PixelResolutionUnit.PixelsPerMeter },
{ TestImages.Png.Ratio1x4, 1, 4, PixelResolutionUnit.AspectRatio },
@ -222,6 +222,33 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
}
}
[Theory]
[WithFile(TestImages.Png.PngWithMetadata, PixelTypes.Rgba32)]
public void Encode_PreservesColorProfile<TPixel>(TestImageProvider<TPixel> provider)
where TPixel : unmanaged, IPixel<TPixel>
{
using (Image<TPixel> input = provider.GetImage(new PngDecoder()))
{
ImageSharp.Metadata.Profiles.Icc.IccProfile expectedProfile = input.Metadata.IccProfile;
byte[] expectedProfileBytes = expectedProfile.ToByteArray();
using (var memStream = new MemoryStream())
{
input.Save(memStream, new PngEncoder());
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]
[MemberData(nameof(RatioFiles))]
public void Identify_VerifyRatio(string imagePath, int xResolution, int yResolution, PixelResolutionUnit resolutionUnit)

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