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All PixelArea<T> usages in JpegEncoder replaced by GenericBlock8x8<TPixel> + YCbCrForwardConverter<TPixel>

pull/475/head
Anton Firszov 8 years ago
parent
bcd33b608e
commit
62f8ba211b
4 changed files with 132 additions and 134 deletions
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  1. 5
      src/ImageSharp/Formats/Jpeg/Common/GenericBlock8x8.cs
  2. 78
      src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/RgbToYCbCrTables.cs
  3. 83
      src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/YCbCrForwardConverter{TPixel}.cs
  4. 100
      src/ImageSharp/Formats/Jpeg/GolangPort/JpegEncoderCore.cs

5
src/ImageSharp/Formats/Jpeg/Common/GenericBlock8x8.cs
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@ -7,9 +7,12 @@ using SixLabors.Primitives;
namespace SixLabors.ImageSharp.Formats.Jpeg.Common
{
using System.Runtime.InteropServices;
/// <summary>
/// A generic 8x8 block implementation, useful for manipulating custom 8x8 pixel data.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
// ReSharper disable once InconsistentNaming
internal unsafe partial struct GenericBlock8x8<T>
where T : struct
@ -87,7 +90,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common
}
/// <summary>
/// ONLY FOR GenericBlock instances living on the stack!
/// Only for on-stack instances!
/// </summary>
public Span<T> AsSpanUnsafe() => new Span<T>(Unsafe.AsPointer(ref this), Size);

78
src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/RgbToYCbCrTables.cs
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@ -2,15 +2,11 @@
// Licensed under the Apache License, Version 2.0.
using System.Runtime.CompilerServices;
using SixLabors.ImageSharp.Advanced;
using SixLabors.ImageSharp.Formats.Jpeg.Common;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.PixelFormats;
namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
{
using System;
/// <summary>
/// Provides 8-bit lookup tables for converting from Rgb to YCbCr colorspace.
/// Methods to build the tables are based on libjpeg implementation.
@ -101,27 +97,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
/// TODO: Replace this logic with SIMD conversion (similar to the one in the decoder)!
/// Optimized method to allocates the correct y, cb, and cr values to the DCT blocks from the given r, g, b values.
/// </summary>
/// <param name="tables">The reference to the tables instance.</param>
/// <param name="yBlockRaw">The The luminance block.</param>
/// <param name="cbBlockRaw">The red chroma block.</param>
/// <param name="crBlockRaw">The blue chroma block.</param>
/// <param name="index">The current index.</param>
/// <param name="r">The red value.</param>
/// <param name="g">The green value.</param>
/// <param name="b">The blue value.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Rgb2YCbCr(RgbToYCbCrTables* tables, float* yBlockRaw, float* cbBlockRaw, float* crBlockRaw, int index, int r, int g, int b)
{
// float y = (0.299F * r) + (0.587F * g) + (0.114F * b);
yBlockRaw[index] = (tables->YRTable[r] + tables->YGTable[g] + tables->YBTable[b]) >> ScaleBits;
// float cb = 128F + ((-0.168736F * r) - (0.331264F * g) + (0.5F * b));
cbBlockRaw[index] = (tables->CbRTable[r] + tables->CbGTable[g] + tables->CbBTable[b]) >> ScaleBits;
// float b = MathF.Round(y + (1.772F * cb), MidpointRounding.AwayFromZero);
crBlockRaw[index] = (tables->CbBTable[r] + tables->CrGTable[g] + tables->CrBTable[b]) >> ScaleBits;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void ConvertPixelInto(int r, int g, int b, ref float yResult, ref float cbResult, ref float crResult)
{
@ -155,55 +130,4 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
return x >> ScaleBits;
}
}
// TODO!
internal struct YCbCrForwardConverter<TPixel>
where TPixel : struct, IPixel<TPixel>
{
public Block8x8F Y;
public Block8x8F Cb;
public Block8x8F Cr;
private RgbToYCbCrTables colorTables;
private GenericBlock8x8<TPixel> pixelBlock;
private GenericBlock8x8<Rgb24> rgbBlock;
public static YCbCrForwardConverter<TPixel> Create()
{
var result = default(YCbCrForwardConverter<TPixel>);
result.colorTables = RgbToYCbCrTables.Create();
return result;
}
public void Convert(IPixelSource<TPixel> pixels, int x, int y)
{
this.pixelBlock.LoadAndStretchEdges(pixels, x, y);
Span<Rgb24> rgbSpan = this.rgbBlock.AsSpanUnsafe();
PixelOperations<TPixel>.Instance.ToRgb24(this.pixelBlock.AsSpanUnsafe(), rgbSpan, 64);
ref float yBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Y);
ref float cbBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cb);
ref float crBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cr);
ref Rgb24 rgbStart = ref rgbSpan[0];
for (int i = 0; i < 64; i++)
{
ref Rgb24 c = ref Unsafe.Add(ref rgbStart, i);
this.colorTables.ConvertPixelInto(
c.R,
c.G,
c.B,
ref Unsafe.Add(ref yBlockStart, i),
ref Unsafe.Add(ref cbBlockStart, i),
ref Unsafe.Add(ref crBlockStart, i)
);
}
}
}
}

83
src/ImageSharp/Formats/Jpeg/GolangPort/Components/Encoder/YCbCrForwardConverter{TPixel}.cs
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@ -0,0 +1,83 @@
using System;
using System.Runtime.CompilerServices;
using SixLabors.ImageSharp.Advanced;
using SixLabors.ImageSharp.Formats.Jpeg.Common;
using SixLabors.ImageSharp.PixelFormats;
namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Encoder
{
/// <summary>
/// On-stack worker struct to efficiently encapsulate the TPixel -> Rgb24 -> YCbCr conversion chain of 8x8 pixel blocks.
/// </summary>
/// <typeparam name="TPixel">The pixel type to work on</typeparam>
internal struct YCbCrForwardConverter<TPixel>
where TPixel : struct, IPixel<TPixel>
{
/// <summary>
/// The Y component
/// </summary>
public Block8x8F Y;
/// <summary>
/// The Cb component
/// </summary>
public Block8x8F Cb;
/// <summary>
/// The Cr component
/// </summary>
public Block8x8F Cr;
/// <summary>
/// The color conversion tables
/// </summary>
private RgbToYCbCrTables colorTables;
/// <summary>
/// Temporal 8x8 block to hold TPixel data
/// </summary>
private GenericBlock8x8<TPixel> pixelBlock;
/// <summary>
/// Temporal RGB block
/// </summary>
private GenericBlock8x8<Rgb24> rgbBlock;
public static YCbCrForwardConverter<TPixel> Create()
{
var result = default(YCbCrForwardConverter<TPixel>);
result.colorTables = RgbToYCbCrTables.Create();
return result;
}
/// <summary>
/// Converts a 8x8 image area inside 'pixels' at position (x,y) placing the result members of the structure (<see cref="Y"/>, <see cref="Cb"/>, <see cref="Cr"/>)
/// </summary>
public void Convert(IPixelSource<TPixel> pixels, int x, int y)
{
this.pixelBlock.LoadAndStretchEdges(pixels, x, y);
Span<Rgb24> rgbSpan = this.rgbBlock.AsSpanUnsafe();
PixelOperations<TPixel>.Instance.ToRgb24(this.pixelBlock.AsSpanUnsafe(), rgbSpan, 64);
ref float yBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Y);
ref float cbBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cb);
ref float crBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cr);
ref Rgb24 rgbStart = ref rgbSpan[0];
for (int i = 0; i < 64; i++)
{
ref Rgb24 c = ref Unsafe.Add(ref rgbStart, i);
this.colorTables.ConvertPixelInto(
c.R,
c.G,
c.B,
ref Unsafe.Add(ref yBlockStart, i),
ref Unsafe.Add(ref cbBlockStart, i),
ref Unsafe.Add(ref crBlockStart, i)
);
}
}
}
}

100
src/ImageSharp/Formats/Jpeg/GolangPort/JpegEncoderCore.cs
View File

@ -868,11 +868,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
this.Encode444(image);
break;
case JpegSubsample.Ratio420:
using (var pixels = image.Lock())
{
this.Encode420(pixels);
}
this.Encode420(image);
break;
}
@ -886,7 +882,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="pixels">The pixel accessor providing access to the image pixels.</param>
private void Encode420<TPixel>(PixelAccessor<TPixel> pixels)
private void Encode420<TPixel>(Image<TPixel> pixels)
where TPixel : struct, IPixel<TPixel>
{
// TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
@ -905,62 +901,54 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
ZigZag unzig = ZigZag.CreateUnzigTable();
var pixelConverter = YCbCrForwardConverter<TPixel>.Create();
// ReSharper disable once InconsistentNaming
int prevDCY = 0, prevDCCb = 0, prevDCCr = 0;
fixed (RgbToYCbCrTables* tables = &rgbToYCbCrTables)
for (int y = 0; y < pixels.Height; y += 16)
{
using (PixelArea<TPixel> rgbBytes = new PixelArea<TPixel>(8, 8, ComponentOrder.Xyz))
for (int x = 0; x < pixels.Width; x += 16)
{
for (int y = 0; y < pixels.Height; y += 16)
for (int i = 0; i < 4; i++)
{
for (int x = 0; x < pixels.Width; x += 16)
{
for (int i = 0; i < 4; i++)
{
int xOff = (i & 1) * 8;
int yOff = (i & 2) * 4;
ToYCbCr(
pixels,
tables,
x + xOff,
y + yOff,
ref b,
ref Unsafe.AsRef<Block8x8F>(cbPtr + i),
ref Unsafe.AsRef<Block8x8F>(crPtr + i),
rgbBytes);
prevDCY = this.WriteBlock(
QuantIndex.Luminance,
prevDCY,
&b,
&temp1,
&temp2,
&onStackLuminanceQuantTable,
unzig.Data);
}
Block8x8F.Scale16X16To8X8(&b, cbPtr);
prevDCCb = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCb,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
Block8x8F.Scale16X16To8X8(&b, crPtr);
prevDCCr = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCr,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
}
int xOff = (i & 1) * 8;
int yOff = (i & 2) * 4;
pixelConverter.Convert(pixels.Frames.RootFrame, x + xOff, y + yOff);
cbPtr[i] = pixelConverter.Cb;
crPtr[i] = pixelConverter.Cr;
prevDCY = this.WriteBlock(
QuantIndex.Luminance,
prevDCY,
&pixelConverter.Y,
&temp1,
&temp2,
&onStackLuminanceQuantTable,
unzig.Data);
}
Block8x8F.Scale16X16To8X8(&b, cbPtr);
prevDCCb = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCb,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
Block8x8F.Scale16X16To8X8(&b, crPtr);
prevDCCr = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCr,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
}
}
}

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