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Encode grayscale png by row.

af/merge-core
James Jackson-South 9 years ago
parent
dd6c05d946
commit
1f960ae41d
1 changed files with 36 additions and 35 deletions
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  1. 71
      src/ImageSharp/Formats/Png/PngEncoderCore.cs

71
src/ImageSharp/Formats/Png/PngEncoderCore.cs
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@ -181,7 +181,7 @@ namespace ImageSharp.Formats
}
else if (this.PngColorType == PngColorType.Grayscale || this.PngColorType == PngColorType.GrayscaleWithAlpha)
{
this.CollectGrayscaleBytes(image);
//this.CollectGrayscaleBytes(image);
}
else
{
@ -253,40 +253,38 @@ namespace ImageSharp.Formats
}
/// <summary>
/// Collects the grayscale pixel data.
/// Collects a row of grayscale pixels.
/// </summary>
/// <typeparam name="TColor">The pixel format.</typeparam>
/// <typeparam name="TPacked">The packed format. <example>uint, long, float.</example></typeparam>
/// <param name="image">The image to encode.</param>
private void CollectGrayscaleBytes<TColor, TPacked>(ImageBase<TColor, TPacked> image)
/// <param name="row">The row index.</param>
/// <param name="rawScanline">The raw scanline.</param>
private void CollectGrayscaleBytes<TColor, TPacked>(ImageBase<TColor, TPacked> image, int row, byte[] rawScanline)
where TColor : struct, IPackedPixel<TPacked>
where TPacked : struct
{
// Copy the pixels across from the image.
this.pixelData = new byte[this.width * this.height * this.bytesPerPixel];
int stride = this.width * this.bytesPerPixel;
byte[] bytes = new byte[4];
using (PixelAccessor<TColor, TPacked> pixels = image.Lock())
{
for (int y = 0; y < this.height; y++)
for (int x = 0; x < this.width; x++)
{
for (int x = 0; x < this.width; x++)
// Convert the color to YCbCr and store the luminance
// Optionally store the original color alpha.
int offset = x * this.bytesPerPixel;
pixels[x, row].ToBytes(bytes, 0, ComponentOrder.XYZW);
byte luminance = (byte)((0.299F * bytes[0]) + (0.587F * bytes[1]) + (0.114F * bytes[2]));
for (int i = 0; i < this.bytesPerPixel; i++)
{
// Convert the color to YCbCr and store the luminance
// Optionally store the original color alpha.
int dataOffset = (y * stride) + (x * this.bytesPerPixel);
pixels[x, y].ToBytes(bytes, 0, ComponentOrder.XYZW);
YCbCr luminance = new Color(bytes[0], bytes[1], bytes[2], bytes[3]);
for (int i = 0; i < this.bytesPerPixel; i++)
if (i == 0)
{
rawScanline[offset] = luminance;
}
else
{
if (i == 0)
{
this.pixelData[dataOffset] = (byte)luminance.Y;
}
else
{
this.pixelData[dataOffset + i] = bytes[3];
}
rawScanline[offset + i] = bytes[3];
}
}
}
@ -294,13 +292,13 @@ namespace ImageSharp.Formats
}
/// <summary>
/// Collects the true color pixel data.
/// Collects a row of true color pixel data.
/// </summary>
/// <typeparam name="TColor">The pixel format.</typeparam>
/// <typeparam name="TPacked">The packed format. <example>uint, long, float.</example></typeparam>
/// <param name="image">The image to encode.</param>
/// <param name="row">The row index.</param>
/// <param name="rawScanline">The raw Scanline.</param>
/// <param name="rawScanline">The raw scanline.</param>
private void CollectColorBytes<TColor, TPacked>(ImageBase<TColor, TPacked> image, int row, byte[] rawScanline)
where TColor : struct, IPackedPixel<TPacked>
where TPacked : struct
@ -312,11 +310,6 @@ namespace ImageSharp.Formats
{
pixels[x, row].ToBytes(rawScanline, x * this.bytesPerPixel, bpp == 4 ? ComponentOrder.XYZW : ComponentOrder.XYZ);
}
if (rawScanline.Any(x => x > 0))
{
var t = rawScanline;
}
}
}
@ -336,13 +329,18 @@ namespace ImageSharp.Formats
where TColor : struct, IPackedPixel<TPacked>
where TPacked : struct
{
if (this.PngColorType == PngColorType.Palette || this.PngColorType == PngColorType.Grayscale || this.PngColorType == PngColorType.GrayscaleWithAlpha)
{
Buffer.BlockCopy(this.pixelData, row * bytesPerScanline, rawScanline, 0, bytesPerScanline);
}
else
switch (this.PngColorType)
{
this.CollectColorBytes(image, row, rawScanline);
case PngColorType.Palette:
Buffer.BlockCopy(this.pixelData, row * bytesPerScanline, rawScanline, 0, bytesPerScanline);
break;
case PngColorType.Grayscale:
case PngColorType.GrayscaleWithAlpha:
this.CollectGrayscaleBytes(image, row, rawScanline);
break;
default:
this.CollectColorBytes(image, row, rawScanline);
break;
}
byte[] filteredScanline = this.GetOptimalFilteredScanline(rawScanline, previousScanline, bytesPerScanline, this.bytesPerPixel);
@ -363,9 +361,10 @@ namespace ImageSharp.Formats
{
Tuple<byte[], int>[] candidates;
// Palette images don't compress well with adaptive filtering.
if (this.PngColorType == PngColorType.Palette)
{
candidates = new Tuple<byte[], int>[4];
candidates = new Tuple<byte[], int>[1];
byte[] none = NoneFilter.Encode(rawScanline);
candidates[0] = new Tuple<byte[], int>(none, this.CalculateTotalVariation(none));
@ -634,6 +633,8 @@ namespace ImageSharp.Formats
memoryStream?.Dispose();
}
// Store the chunks in repeated 64k blocks.
// This reduces the memory load for decoding the image for many decoders.
int numChunks = bufferLength / MaxBlockSize;
if (bufferLength % MaxBlockSize != 0)

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