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Merge pull request #1289 from stevetemple/webp-chunkconfig 

Work out the crunch configs for lossless webp
pull/1552/head
Brian Popow 6 years ago
committed by GitHub
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af7eae82ac 84cfe3b386
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2 changed files with 126 additions and 60 deletions
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  1. 4
      src/ImageSharp/Formats/WebP/EntropyIx.cs
  2. 182
      src/ImageSharp/Formats/WebP/Lossless/Vp8LEncoder.cs

4
src/ImageSharp/Formats/WebP/EntropyIx.cs
View File

@ -18,6 +18,8 @@ namespace SixLabors.ImageSharp.Formats.WebP
Palette = 4,
NumEntropyIx = 5
PaletteAndSpatial = 5,
NumEntropyIx = 6
}
}

182
src/ImageSharp/Formats/WebP/Lossless/Vp8LEncoder.cs
View File

@ -6,6 +6,7 @@ using System.Buffers;
using System.Buffers.Binary;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using SixLabors.ImageSharp.Formats.WebP.BitWriter;
@ -38,7 +39,7 @@ namespace SixLabors.ImageSharp.Formats.WebP.Lossless
/// A bit writer for writing lossless webp streams.
/// </summary>
private Vp8LBitWriter bitWriter;
private const int ApplyPaletteGreedyMax = 4;
private const int PaletteInvSizeBits = 11;
@ -252,66 +253,74 @@ namespace SixLabors.ImageSharp.Formats.WebP.Lossless
}
// Analyze image (entropy, numPalettes etc).
this.EncoderAnalyze(image);
CrunchConfig[] crunchConfigs = this.EncoderAnalyze(image, out bool redAndBlueAlwaysZero);
var entropyIdx = 3; // TODO: hardcoded for now.
int quality = 75; // TODO: quality is hardcoded for now.
bool useCache = true; // TODO: useCache is hardcoded for now.
bool redAndBlueAlwaysZero = false;
this.UsePalette = entropyIdx == (int)EntropyIx.Palette;
this.UseSubtractGreenTransform = (entropyIdx == (int)EntropyIx.SubGreen) || (entropyIdx == (int)EntropyIx.SpatialSubGreen);
this.UsePredictorTransform = (entropyIdx == (int)EntropyIx.Spatial) || (entropyIdx == (int)EntropyIx.SpatialSubGreen);
this.UseCrossColorTransform = redAndBlueAlwaysZero ? false : this.UsePredictorTransform;
this.AllocateTransformBuffer(width, height);
// Reset any parameter in the encoder that is set in the previous iteration.
this.CacheBits = 0;
this.ClearRefs();
// TODO : Do we want to do this multi-threaded, this will probably require a second class:
// one which co-ordinates the threading and comparison and another which does the actual encoding
foreach (CrunchConfig crunchConfig in crunchConfigs)
{
bool useCache = true;
this.UsePalette = crunchConfig.EntropyIdx == EntropyIx.Palette || crunchConfig.EntropyIdx == EntropyIx.PaletteAndSpatial;
this.UseSubtractGreenTransform = (crunchConfig.EntropyIdx == EntropyIx.SubGreen) ||
(crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen);
this.UsePredictorTransform = (crunchConfig.EntropyIdx == EntropyIx.Spatial) ||
(crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen);
this.UseCrossColorTransform = redAndBlueAlwaysZero ? false : this.UsePredictorTransform;
this.AllocateTransformBuffer(width, height);
// Reset any parameter in the encoder that is set in the previous iteration.
this.CacheBits = 0;
this.ClearRefs();
// TODO: Apply near-lossless preprocessing.
// Encode palette.
if (this.UsePalette)
{
this.EncodePalette();
this.MapImageFromPalette(width, height);
// TODO: Apply near-lossless preprocessing.
// If using a color cache, do not have it bigger than the number of colors.
if (useCache && this.PaletteSize < (1 << WebPConstants.MaxColorCacheBits))
{
this.CacheBits = WebPCommonUtils.BitsLog2Floor((uint)this.PaletteSize) + 1;
}
}
// Encode palette.
if (this.UsePalette)
{
this.EncodePalette();
this.MapImageFromPalette(width, height);
// Apply transforms and write transform data.
if (this.UseSubtractGreenTransform)
{
this.ApplySubtractGreen(this.CurrentWidth, height);
}
// If using a color cache, do not have it bigger than the number of colors.
if (useCache && this.PaletteSize < (1 << WebPConstants.MaxColorCacheBits))
if (this.UsePredictorTransform)
{
this.CacheBits = WebPCommonUtils.BitsLog2Floor((uint)this.PaletteSize) + 1;
this.ApplyPredictFilter(this.CurrentWidth, height, quality, this.UseSubtractGreenTransform);
}
}
// Apply transforms and write transform data.
if (this.UseSubtractGreenTransform)
{
this.ApplySubtractGreen(this.CurrentWidth, height);
}
if (this.UseCrossColorTransform)
{
this.ApplyCrossColorFilter(this.CurrentWidth, height, quality);
}
if (this.UsePredictorTransform)
{
this.ApplyPredictFilter(this.CurrentWidth, height, quality, this.UseSubtractGreenTransform);
}
this.bitWriter.PutBits(0, 1); // No more transforms.
if (this.UseCrossColorTransform)
{
this.ApplyCrossColorFilter(this.CurrentWidth, height, quality);
// Encode and write the transformed image.
this.EncodeImage(bgra, this.HashChain, this.Refs, this.CurrentWidth, height, quality, useCache, crunchConfig,
this.CacheBits, this.HistoBits, bytePosition);
}
this.bitWriter.PutBits(0, 1); // No more transforms.
// Encode and write the transformed image.
this.EncodeImage(bgra, this.HashChain, this.Refs, this.CurrentWidth, height, quality, useCache, this.CacheBits, this.HistoBits, bytePosition);
// TODO: Comparison and picking of best (smallest) encoding
}
/// <summary>
/// Analyzes the image and decides what transforms should be used.
/// </summary>
private void EncoderAnalyze<TPixel>(Image<TPixel> image)
private CrunchConfig[] EncoderAnalyze<TPixel>(Image<TPixel> image, out bool redAndBlueAlwaysZero)
where TPixel : unmanaged, IPixel<TPixel>
{
var configQuality = 75; // TODO: hardcoded quality for now
int method = 4; // TODO: method hardcoded to 4 for now.
int width = image.Width;
int height = image.Height;
@ -325,15 +334,61 @@ namespace SixLabors.ImageSharp.Formats.WebP.Lossless
// Try out multiple LZ77 on images with few colors.
var nlz77s = (this.PaletteSize > 0 && this.PaletteSize <= 16) ? 2 : 1;
EntropyIx entropyIdx = this.AnalyzeEntropy(image, usePalette, this.PaletteSize, this.TransformBits, out bool redAndBlueAlwaysZero);
EntropyIx entropyIdx = this.AnalyzeEntropy(image, usePalette, this.PaletteSize, this.TransformBits, out redAndBlueAlwaysZero);
bool doNotCache = false;
var crunchConfigs = new List<CrunchConfig>();
if (method == 6 && configQuality == 100)
{
doNotCache = true;
// TODO: Fill CrunchConfig
// Go brute force on all transforms.
foreach (EntropyIx entropyIx in Enum.GetValues(typeof(EntropyIx)).Cast<EntropyIx>())
{
// We can only apply kPalette or kPaletteAndSpatial if we can indeed use
// a palette.
if ((entropyIx != EntropyIx.Palette && entropyIx != EntropyIx.PaletteAndSpatial) || usePalette)
{
crunchConfigs.Add(new CrunchConfig { EntropyIdx = entropyIx });
}
}
}
else
{
// Only choose the guessed best transform.
crunchConfigs.Add(new CrunchConfig {EntropyIdx = entropyIdx});
if (configQuality >= 75 && method == 5)
{
// Test with and without color cache.
doNotCache = true;
// If we have a palette, also check in combination with spatial.
if (entropyIdx == EntropyIx.Palette)
{
crunchConfigs.Add(new CrunchConfig { EntropyIdx = EntropyIx.PaletteAndSpatial});
}
}
}
// Fill in the different LZ77s.
foreach (CrunchConfig crunchConfig in crunchConfigs)
{
for (var j = 0; j < nlz77s; ++j)
{
crunchConfig.SubConfigs.Add(new CrunchSubConfig
{
Lz77 = (j == 0) ? (int)Vp8LLz77Type.Lz77Standard | (int)Vp8LLz77Type.Lz77Rle : (int)Vp8LLz77Type.Lz77Box,
DoNotCache = doNotCache
});
}
}
return crunchConfigs.ToArray();
}
private void EncodeImage(Span<uint> bgra, Vp8LHashChain hashChain, Vp8LBackwardRefs[] refsArray, int width, int height, int quality, bool useCache, int cacheBits, int histogramBits, int initBytePosition)
private void EncodeImage(Span<uint> bgra, Vp8LHashChain hashChain, Vp8LBackwardRefs[] refsArray, int width, int height, int quality, bool useCache, CrunchConfig config, int cacheBits, int histogramBits, int initBytePosition)
{
int lz77sTypesToTrySize = 1; // TODO: hardcoded for now.
int[] lz77sTypesToTry = { 3 };
int histogramImageXySize = LosslessUtils.SubSampleSize(width, histogramBits) * LosslessUtils.SubSampleSize(height, histogramBits);
var histogramSymbols = new short[histogramImageXySize];
var huffTree = new HuffmanTree[3 * WebPConstants.CodeLengthCodes];
@ -357,24 +412,17 @@ namespace SixLabors.ImageSharp.Formats.WebP.Lossless
// Calculate backward references from BGRA image.
BackwardReferenceEncoder.HashChainFill(hashChain, bgra, quality, width, height);
Vp8LBitWriter bitWriterBest = null;
if (lz77sTypesToTrySize > 1)
{
bitWriterBest = this.bitWriter.Clone();
}
else
{
bitWriterBest = this.bitWriter;
}
Vp8LBitWriter bitWriterBest = config.SubConfigs.Count > 1 ? this.bitWriter.Clone() : this.bitWriter;
for (int lz77sIdx = 0; lz77sIdx < lz77sTypesToTrySize; lz77sIdx++)
foreach (CrunchSubConfig subConfig in config.SubConfigs)
{
Vp8LBackwardRefs refsBest = BackwardReferenceEncoder.GetBackwardReferences(width, height, bgra, quality, lz77sTypesToTry[lz77sIdx], ref cacheBits, hashChain, refsArray[0], refsArray[1]);
Vp8LBackwardRefs refsBest = BackwardReferenceEncoder.GetBackwardReferences(width, height, bgra, quality, subConfig.Lz77, ref cacheBits, hashChain, refsArray[0], refsArray[1]); // TODO : Pass do not cache
// Keep the best references aside and use the other element from the first
// two as a temporary for later usage.
Vp8LBackwardRefs refsTmp = refsArray[refsBest.Equals(refsArray[0]) ? 1 : 0];
// TODO : Loop based on cache/no cache
// TODO: this.bitWriter.Reset();
var tmpHisto = new Vp8LHistogram(cacheBits);
var histogramImage = new List<Vp8LHistogram>(histogramImageXySize);
@ -1567,5 +1615,21 @@ namespace SixLabors.ImageSharp.Formats.WebP.Lossless
this.Palette.Dispose();
this.TransformData.Dispose();
}
// TODO : Not a fan of private classes
private class CrunchConfig
{
public EntropyIx EntropyIdx { get; set; }
public List<CrunchSubConfig> SubConfigs { get; } = new List<CrunchSubConfig>();
}
// TODO : Not a fan of private classes
private class CrunchSubConfig
{
public int Lz77 { get; set; }
public bool DoNotCache { get; set; }
}
}
}

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