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Merge pull request #2108 from SixLabors/bp/bmp-icc
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Preserve color profile when encoding bitmaps
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@brianpopow
brianpopow authored May 7, 2022
2 parents d2bad1f + 5388489 commit 2aa150c
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Showing 11 changed files with 388 additions and 78 deletions.
37 changes: 37 additions & 0 deletions src/ImageSharp/Formats/Bmp/BmpColorSpace.cs
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@@ -0,0 +1,37 @@
// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.

// ReSharper disable InconsistentNaming
namespace SixLabors.ImageSharp.Formats.Bmp
{
/// <summary>
/// Enum for the different color spaces.
/// </summary>
internal enum BmpColorSpace
{
/// <summary>
/// This value implies that endpoints and gamma values are given in the appropriate fields.
/// </summary>
LCS_CALIBRATED_RGB = 0,

/// <summary>
/// The Windows default color space ('Win ').
/// </summary>
LCS_WINDOWS_COLOR_SPACE = 1466527264,

/// <summary>
/// Specifies that the bitmap is in sRGB color space ('sRGB').
/// </summary>
LCS_sRGB = 1934772034,

/// <summary>
/// This value indicates that bV5ProfileData points to the file name of the profile to use (gamma and endpoints values are ignored).
/// </summary>
PROFILE_LINKED = 1279872587,

/// <summary>
/// This value indicates that bV5ProfileData points to a memory buffer that contains the profile to be used (gamma and endpoints values are ignored).
/// </summary>
PROFILE_EMBEDDED = 1296188740
}
}
53 changes: 34 additions & 19 deletions src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
using SixLabors.ImageSharp.IO;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.Metadata;
using SixLabors.ImageSharp.Metadata.Profiles.Icc;
using SixLabors.ImageSharp.PixelFormats;

namespace SixLabors.ImageSharp.Formats.Bmp
Expand Down Expand Up @@ -185,7 +186,7 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
break;

default:
BmpThrowHelper.ThrowNotSupportedException("Does not support this kind of bitmap files.");
BmpThrowHelper.ThrowNotSupportedException("ImageSharp does not support this kind of bitmap files.");

break;
}
Expand Down Expand Up @@ -1199,6 +1200,13 @@ private static int CountBits(uint n)
private void ReadInfoHeader()
{
Span<byte> buffer = stackalloc byte[BmpInfoHeader.MaxHeaderSize];
long infoHeaderStart = this.stream.Position;

// Resolution is stored in PPM.
this.metadata = new ImageMetadata
{
ResolutionUnits = PixelResolutionUnit.PixelsPerMeter
};

// Read the header size.
this.stream.Read(buffer, 0, BmpInfoHeader.HeaderSizeSize);
Expand Down Expand Up @@ -1271,36 +1279,45 @@ private void ReadInfoHeader()
infoHeaderType = BmpInfoHeaderType.Os2Version2;
this.infoHeader = BmpInfoHeader.ParseOs2Version2(buffer);
}
else if (headerSize >= BmpInfoHeader.SizeV4)
else if (headerSize == BmpInfoHeader.SizeV4)
{
// >= 108 bytes
infoHeaderType = headerSize == BmpInfoHeader.SizeV4 ? BmpInfoHeaderType.WinVersion4 : BmpInfoHeaderType.WinVersion5;
// == 108 bytes
infoHeaderType = BmpInfoHeaderType.WinVersion4;
this.infoHeader = BmpInfoHeader.ParseV4(buffer);
}
else if (headerSize > BmpInfoHeader.SizeV4)
{
// > 108 bytes
infoHeaderType = BmpInfoHeaderType.WinVersion5;
this.infoHeader = BmpInfoHeader.ParseV5(buffer);
if (this.infoHeader.ProfileData != 0 && this.infoHeader.ProfileSize != 0)
{
// Read color profile.
long streamPosition = this.stream.Position;
byte[] iccProfileData = new byte[this.infoHeader.ProfileSize];
this.stream.Position = infoHeaderStart + this.infoHeader.ProfileData;
this.stream.Read(iccProfileData);
this.metadata.IccProfile = new IccProfile(iccProfileData);
this.stream.Position = streamPosition;
}
}
else
{
BmpThrowHelper.ThrowNotSupportedException($"ImageSharp does not support this BMP file. HeaderSize '{headerSize}'.");
}

// Resolution is stored in PPM.
var meta = new ImageMetadata
{
ResolutionUnits = PixelResolutionUnit.PixelsPerMeter
};
if (this.infoHeader.XPelsPerMeter > 0 && this.infoHeader.YPelsPerMeter > 0)
{
meta.HorizontalResolution = this.infoHeader.XPelsPerMeter;
meta.VerticalResolution = this.infoHeader.YPelsPerMeter;
this.metadata.HorizontalResolution = this.infoHeader.XPelsPerMeter;
this.metadata.VerticalResolution = this.infoHeader.YPelsPerMeter;
}
else
{
// Convert default metadata values to PPM.
meta.HorizontalResolution = Math.Round(UnitConverter.InchToMeter(ImageMetadata.DefaultHorizontalResolution));
meta.VerticalResolution = Math.Round(UnitConverter.InchToMeter(ImageMetadata.DefaultVerticalResolution));
this.metadata.HorizontalResolution = Math.Round(UnitConverter.InchToMeter(ImageMetadata.DefaultHorizontalResolution));
this.metadata.VerticalResolution = Math.Round(UnitConverter.InchToMeter(ImageMetadata.DefaultVerticalResolution));
}

this.metadata = meta;

short bitsPerPixel = this.infoHeader.BitsPerPixel;
this.bmpMetadata = this.metadata.GetBmpMetadata();
this.bmpMetadata.InfoHeaderType = infoHeaderType;
Expand Down Expand Up @@ -1370,9 +1387,7 @@ private int ReadImageHeaders(BufferedReadStream stream, out bool inverted, out b
int colorMapSizeBytes = -1;
if (this.infoHeader.ClrUsed == 0)
{
if (this.infoHeader.BitsPerPixel == 1
|| this.infoHeader.BitsPerPixel == 4
|| this.infoHeader.BitsPerPixel == 8)
if (this.infoHeader.BitsPerPixel is 1 or 4 or 8)
{
switch (this.fileMarkerType)
{
Expand Down Expand Up @@ -1424,7 +1439,7 @@ private int ReadImageHeaders(BufferedReadStream stream, out bool inverted, out b
int skipAmount = this.fileHeader.Offset - (int)this.stream.Position;
if ((skipAmount + (int)this.stream.Position) > this.stream.Length)
{
BmpThrowHelper.ThrowInvalidImageContentException("Invalid fileheader offset found. Offset is greater than the stream length.");
BmpThrowHelper.ThrowInvalidImageContentException("Invalid file header offset found. Offset is greater than the stream length.");
}

if (skipAmount > 0)
Expand Down
150 changes: 120 additions & 30 deletions src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
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Expand Up @@ -3,6 +3,7 @@

using System;
using System.Buffers;
using System.Buffers.Binary;
using System.IO;
using System.Runtime.InteropServices;
using System.Threading;
Expand Down Expand Up @@ -79,9 +80,10 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
/// <summary>
/// A bitmap v4 header will only be written, if the user explicitly wants support for transparency.
/// In this case the compression type BITFIELDS will be used.
/// If the image contains a color profile, a bitmap v5 header is written, which is needed to write this info.
/// Otherwise a bitmap v3 header will be written, which is supported by almost all decoders.
/// </summary>
private readonly bool writeV4Header;
private BmpInfoHeaderType infoHeaderType;

/// <summary>
/// The quantizer for reducing the color count for 8-Bit, 4-Bit and 1-Bit images.
Expand All @@ -97,8 +99,8 @@ public BmpEncoderCore(IBmpEncoderOptions options, MemoryAllocator memoryAllocato
{
this.memoryAllocator = memoryAllocator;
this.bitsPerPixel = options.BitsPerPixel;
this.writeV4Header = options.SupportTransparency;
this.quantizer = options.Quantizer ?? KnownQuantizers.Octree;
this.infoHeaderType = options.SupportTransparency ? BmpInfoHeaderType.WinVersion4 : BmpInfoHeaderType.WinVersion3;
}

/// <summary>
Expand All @@ -123,7 +125,62 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
int bytesPerLine = 4 * (((image.Width * bpp) + 31) / 32);
this.padding = bytesPerLine - (int)(image.Width * (bpp / 8F));

// Set Resolution.
int colorPaletteSize = 0;
if (this.bitsPerPixel == BmpBitsPerPixel.Pixel8)
{
colorPaletteSize = ColorPaletteSize8Bit;
}
else if (this.bitsPerPixel == BmpBitsPerPixel.Pixel4)
{
colorPaletteSize = ColorPaletteSize4Bit;
}
else if (this.bitsPerPixel == BmpBitsPerPixel.Pixel1)
{
colorPaletteSize = ColorPaletteSize1Bit;
}

byte[] iccProfileData = null;
int iccProfileSize = 0;
if (metadata.IccProfile != null)
{
this.infoHeaderType = BmpInfoHeaderType.WinVersion5;
iccProfileData = metadata.IccProfile.ToByteArray();
iccProfileSize = iccProfileData.Length;
}

int infoHeaderSize = this.infoHeaderType switch
{
BmpInfoHeaderType.WinVersion3 => BmpInfoHeader.SizeV3,
BmpInfoHeaderType.WinVersion4 => BmpInfoHeader.SizeV4,
BmpInfoHeaderType.WinVersion5 => BmpInfoHeader.SizeV5,
_ => BmpInfoHeader.SizeV3
};

BmpInfoHeader infoHeader = this.CreateBmpInfoHeader(image.Width, image.Height, infoHeaderSize, bpp, bytesPerLine, metadata, iccProfileData);

Span<byte> buffer = stackalloc byte[infoHeaderSize];

this.WriteBitmapFileHeader(stream, infoHeaderSize, colorPaletteSize, iccProfileSize, infoHeader, buffer);
this.WriteBitmapInfoHeader(stream, infoHeader, buffer, infoHeaderSize);
this.WriteImage(stream, image.Frames.RootFrame);
this.WriteColorProfile(stream, iccProfileData, buffer);

stream.Flush();
}

/// <summary>
/// Creates the bitmap information header.
/// </summary>
/// <param name="width">The width of the image.</param>
/// <param name="height">The height of the image.</param>
/// <param name="infoHeaderSize">Size of the information header.</param>
/// <param name="bpp">The bits per pixel.</param>
/// <param name="bytesPerLine">The bytes per line.</param>
/// <param name="metadata">The metadata.</param>
/// <param name="iccProfileData">The icc profile data.</param>
/// <returns>The bitmap information header.</returns>
private BmpInfoHeader CreateBmpInfoHeader(int width, int height, int infoHeaderSize, short bpp, int bytesPerLine, ImageMetadata metadata, byte[] iccProfileData)
{
int hResolution = 0;
int vResolution = 0;

Expand Down Expand Up @@ -154,20 +211,19 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
}
}

int infoHeaderSize = this.writeV4Header ? BmpInfoHeader.SizeV4 : BmpInfoHeader.SizeV3;
var infoHeader = new BmpInfoHeader(
headerSize: infoHeaderSize,
height: image.Height,
width: image.Width,
height: height,
width: width,
bitsPerPixel: bpp,
planes: 1,
imageSize: image.Height * bytesPerLine,
imageSize: height * bytesPerLine,
clrUsed: 0,
clrImportant: 0,
xPelsPerMeter: hResolution,
yPelsPerMeter: vResolution);

if (this.writeV4Header && this.bitsPerPixel == BmpBitsPerPixel.Pixel32)
if ((this.infoHeaderType is BmpInfoHeaderType.WinVersion4 or BmpInfoHeaderType.WinVersion5) && this.bitsPerPixel == BmpBitsPerPixel.Pixel32)
{
infoHeader.AlphaMask = Rgba32AlphaMask;
infoHeader.RedMask = Rgba32RedMask;
Expand All @@ -176,45 +232,79 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken
infoHeader.Compression = BmpCompression.BitFields;
}

int colorPaletteSize = 0;
if (this.bitsPerPixel == BmpBitsPerPixel.Pixel8)
if (this.infoHeaderType is BmpInfoHeaderType.WinVersion5 && metadata.IccProfile != null)
{
colorPaletteSize = ColorPaletteSize8Bit;
infoHeader.ProfileSize = iccProfileData.Length;
infoHeader.CsType = BmpColorSpace.PROFILE_EMBEDDED;
infoHeader.Intent = BmpRenderingIntent.LCS_GM_IMAGES;
}
else if (this.bitsPerPixel == BmpBitsPerPixel.Pixel4)
{
colorPaletteSize = ColorPaletteSize4Bit;
}
else if (this.bitsPerPixel == BmpBitsPerPixel.Pixel1)

return infoHeader;
}

/// <summary>
/// Writes the color profile to the stream.
/// </summary>
/// <param name="stream">The stream to write to.</param>
/// <param name="iccProfileData">The color profile data.</param>
/// <param name="buffer">The buffer.</param>
private void WriteColorProfile(Stream stream, byte[] iccProfileData, Span<byte> buffer)
{
if (iccProfileData != null)
{
colorPaletteSize = ColorPaletteSize1Bit;
// 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));
}
}

/// <summary>
/// Writes the bitmap file header.
/// </summary>
/// <param name="stream">The stream to write the header to.</param>
/// <param name="infoHeaderSize">Size of the bitmap information header.</param>
/// <param name="colorPaletteSize">Size of the color palette.</param>
/// <param name="iccProfileSize">The size in bytes of the color profile.</param>
/// <param name="infoHeader">The information header to write.</param>
/// <param name="buffer">The buffer to write to.</param>
private void WriteBitmapFileHeader(Stream stream, int infoHeaderSize, int colorPaletteSize, int iccProfileSize, BmpInfoHeader infoHeader, Span<byte> buffer)
{
var fileHeader = new BmpFileHeader(
type: BmpConstants.TypeMarkers.Bitmap,
fileSize: BmpFileHeader.Size + infoHeaderSize + colorPaletteSize + infoHeader.ImageSize,
fileSize: BmpFileHeader.Size + infoHeaderSize + colorPaletteSize + iccProfileSize + infoHeader.ImageSize,
reserved: 0,
offset: BmpFileHeader.Size + infoHeaderSize + colorPaletteSize);

Span<byte> buffer = stackalloc byte[infoHeaderSize];
fileHeader.WriteTo(buffer);

stream.Write(buffer, 0, BmpFileHeader.Size);
}

if (this.writeV4Header)
{
infoHeader.WriteV4Header(buffer);
}
else
/// <summary>
/// Writes the bitmap information header.
/// </summary>
/// <param name="stream">The stream to write info header into.</param>
/// <param name="infoHeader">The information header.</param>
/// <param name="buffer">The buffer.</param>
/// <param name="infoHeaderSize">Size of the information header.</param>
private void WriteBitmapInfoHeader(Stream stream, BmpInfoHeader infoHeader, Span<byte> buffer, int infoHeaderSize)
{
switch (this.infoHeaderType)
{
infoHeader.WriteV3Header(buffer);
case BmpInfoHeaderType.WinVersion3:
infoHeader.WriteV3Header(buffer);
break;
case BmpInfoHeaderType.WinVersion4:
infoHeader.WriteV4Header(buffer);
break;
case BmpInfoHeaderType.WinVersion5:
infoHeader.WriteV5Header(buffer);
break;
}

stream.Write(buffer, 0, infoHeaderSize);

this.WriteImage(stream, image.Frames.RootFrame);

stream.Flush();
}

/// <summary>
Expand Down
5 changes: 1 addition & 4 deletions src/ImageSharp/Formats/Bmp/BmpFileHeader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,10 +57,7 @@ public BmpFileHeader(short type, int fileSize, int reserved, int offset)
/// </summary>
public int Offset { get; }

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

public void WriteTo(Span<byte> buffer)
{
Expand Down
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