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Merge pull request #1431 from SixLabors/bp/fix1429 

Use GetPixelRowSpan to access pixel data in Histogram equalization
js/color-alpha-handling
Brian Popow 5 years ago
committed by GitHub
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3 changed files with 83 additions and 40 deletions
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  1. 62
      src/ImageSharp/Processing/Processors/Normalization/AdaptiveHistogramEqualizationProcessor{TPixel}.cs
  2. 8
      src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs
  3. 53
      tests/ImageSharp.Benchmarks/Processing/HistogramEqualization.cs

62
src/ImageSharp/Processing/Processors/Normalization/AdaptiveHistogramEqualizationProcessor{TPixel}.cs
View File

@ -86,42 +86,39 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
new Rectangle(0, 0, sourceWidth, tileYStartPositions.Count), new Rectangle(0, 0, sourceWidth, tileYStartPositions.Count),
in operation); in operation);
ref TPixel pixelsBase = ref source.GetPixelReference(0, 0);
// Fix left column // Fix left column
ProcessBorderColumn(ref pixelsBase, cdfData, 0, sourceWidth, sourceHeight, this.Tiles, tileHeight, xStart: 0, xEnd: halfTileWidth, luminanceLevels); ProcessBorderColumn(source, cdfData, 0, sourceHeight, this.Tiles, tileHeight, xStart: 0, xEnd: halfTileWidth, luminanceLevels);
// Fix right column // Fix right column
int rightBorderStartX = ((this.Tiles - 1) * tileWidth) + halfTileWidth; int rightBorderStartX = ((this.Tiles - 1) * tileWidth) + halfTileWidth;
ProcessBorderColumn(ref pixelsBase, cdfData, this.Tiles - 1, sourceWidth, sourceHeight, this.Tiles, tileHeight, xStart: rightBorderStartX, xEnd: sourceWidth, luminanceLevels); ProcessBorderColumn(source, cdfData, this.Tiles - 1, sourceHeight, this.Tiles, tileHeight, xStart: rightBorderStartX, xEnd: sourceWidth, luminanceLevels);
// Fix top row // Fix top row
ProcessBorderRow(ref pixelsBase, cdfData, 0, sourceWidth, this.Tiles, tileWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels); ProcessBorderRow(source, cdfData, 0, sourceWidth, this.Tiles, tileWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels);
// Fix bottom row // Fix bottom row
int bottomBorderStartY = ((this.Tiles - 1) * tileHeight) + halfTileHeight; int bottomBorderStartY = ((this.Tiles - 1) * tileHeight) + halfTileHeight;
ProcessBorderRow(ref pixelsBase, cdfData, this.Tiles - 1, sourceWidth, this.Tiles, tileWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels); ProcessBorderRow(source, cdfData, this.Tiles - 1, sourceWidth, this.Tiles, tileWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels);
// Left top corner // Left top corner
ProcessCornerTile(ref pixelsBase, cdfData, sourceWidth, 0, 0, xStart: 0, xEnd: halfTileWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels); ProcessCornerTile(source, cdfData, 0, 0, xStart: 0, xEnd: halfTileWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels);
// Left bottom corner // Left bottom corner
ProcessCornerTile(ref pixelsBase, cdfData, sourceWidth, 0, this.Tiles - 1, xStart: 0, xEnd: halfTileWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels); ProcessCornerTile(source, cdfData, 0, this.Tiles - 1, xStart: 0, xEnd: halfTileWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels);
// Right top corner // Right top corner
ProcessCornerTile(ref pixelsBase, cdfData, sourceWidth, this.Tiles - 1, 0, xStart: rightBorderStartX, xEnd: sourceWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels); ProcessCornerTile(source, cdfData, this.Tiles - 1, 0, xStart: rightBorderStartX, xEnd: sourceWidth, yStart: 0, yEnd: halfTileHeight, luminanceLevels);
// Right bottom corner // Right bottom corner
ProcessCornerTile(ref pixelsBase, cdfData, sourceWidth, this.Tiles - 1, this.Tiles - 1, xStart: rightBorderStartX, xEnd: sourceWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels); ProcessCornerTile(source, cdfData, this.Tiles - 1, this.Tiles - 1, xStart: rightBorderStartX, xEnd: sourceWidth, yStart: bottomBorderStartY, yEnd: sourceHeight, luminanceLevels);
} }
} }
/// <summary> /// <summary>
/// Processes the part of a corner tile which was previously left out. It consists of 1 / 4 of a tile and does not need interpolation. /// Processes the part of a corner tile which was previously left out. It consists of 1 / 4 of a tile and does not need interpolation.
/// </summary> /// </summary>
/// <param name="pixelsBase">The output pixels base reference.</param> /// <param name="source">The source image.</param>
/// <param name="cdfData">The lookup table to remap the grey values.</param> /// <param name="cdfData">The lookup table to remap the grey values.</param>
/// <param name="sourceWidth">The source image width.</param>
/// <param name="cdfX">The x-position in the CDF lookup map.</param> /// <param name="cdfX">The x-position in the CDF lookup map.</param>
/// <param name="cdfY">The y-position in the CDF lookup map.</param> /// <param name="cdfY">The y-position in the CDF lookup map.</param>
/// <param name="xStart">X start position.</param> /// <param name="xStart">X start position.</param>
@ -133,9 +130,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
/// or 65536 for 16-bit grayscale images. /// or 65536 for 16-bit grayscale images.
/// </param> /// </param>
private static void ProcessCornerTile( private static void ProcessCornerTile(
ref TPixel pixelsBase, ImageFrame<TPixel> source,
CdfTileData cdfData, CdfTileData cdfData,
int sourceWidth,
int cdfX, int cdfX,
int cdfY, int cdfY,
int xStart, int xStart,
@ -146,10 +142,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
{ {
for (int dy = yStart; dy < yEnd; dy++) for (int dy = yStart; dy < yEnd; dy++)
{ {
int dyOffSet = dy * sourceWidth; Span<TPixel> rowSpan = source.GetPixelRowSpan(dy);
for (int dx = xStart; dx < xEnd; dx++) for (int dx = xStart; dx < xEnd; dx++)
{ {
ref TPixel pixel = ref Unsafe.Add(ref pixelsBase, dyOffSet + dx); ref TPixel pixel = ref rowSpan[dx];
float luminanceEqualized = cdfData.RemapGreyValue(cdfX, cdfY, GetLuminance(pixel, luminanceLevels)); float luminanceEqualized = cdfData.RemapGreyValue(cdfX, cdfY, GetLuminance(pixel, luminanceLevels));
pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W)); pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W));
} }
@ -159,10 +155,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
/// <summary> /// <summary>
/// Processes a border column of the image which is half the size of the tile width. /// Processes a border column of the image which is half the size of the tile width.
/// </summary> /// </summary>
/// <param name="pixelBase">The output pixels reference.</param> /// <param name="source">The source image.</param>
/// <param name="cdfData">The pre-computed lookup tables to remap the grey values for each tiles.</param> /// <param name="cdfData">The pre-computed lookup tables to remap the grey values for each tiles.</param>
/// <param name="cdfX">The X index of the lookup table to use.</param> /// <param name="cdfX">The X index of the lookup table to use.</param>
/// <param name="sourceWidth">The source image width.</param>
/// <param name="sourceHeight">The source image height.</param> /// <param name="sourceHeight">The source image height.</param>
/// <param name="tileCount">The number of vertical tiles.</param> /// <param name="tileCount">The number of vertical tiles.</param>
/// <param name="tileHeight">The height of a tile.</param> /// <param name="tileHeight">The height of a tile.</param>
@ -173,10 +168,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
/// or 65536 for 16-bit grayscale images. /// or 65536 for 16-bit grayscale images.
/// </param> /// </param>
private static void ProcessBorderColumn( private static void ProcessBorderColumn(
ref TPixel pixelBase, ImageFrame<TPixel> source,
CdfTileData cdfData, CdfTileData cdfData,
int cdfX, int cdfX,
int sourceWidth,
int sourceHeight, int sourceHeight,
int tileCount, int tileCount,
int tileHeight, int tileHeight,
@ -194,10 +188,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
int tileY = 0; int tileY = 0;
for (int dy = y; dy < yLimit; dy++) for (int dy = y; dy < yLimit; dy++)
{ {
int dyOffSet = dy * sourceWidth; Span<TPixel> rowSpan = source.GetPixelRowSpan(dy);
for (int dx = xStart; dx < xEnd; dx++) for (int dx = xStart; dx < xEnd; dx++)
{ {
ref TPixel pixel = ref Unsafe.Add(ref pixelBase, dyOffSet + dx); ref TPixel pixel = ref rowSpan[dx];
float luminanceEqualized = InterpolateBetweenTwoTiles(pixel, cdfData, cdfX, cdfY, cdfX, cdfY + 1, tileY, tileHeight, luminanceLevels); float luminanceEqualized = InterpolateBetweenTwoTiles(pixel, cdfData, cdfX, cdfY, cdfX, cdfY + 1, tileY, tileHeight, luminanceLevels);
pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W)); pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W));
} }
@ -213,7 +207,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
/// <summary> /// <summary>
/// Processes a border row of the image which is half of the size of the tile height. /// Processes a border row of the image which is half of the size of the tile height.
/// </summary> /// </summary>
/// <param name="pixelBase">The output pixels base reference.</param> /// <param name="source">The source image.</param>
/// <param name="cdfData">The pre-computed lookup tables to remap the grey values for each tiles.</param> /// <param name="cdfData">The pre-computed lookup tables to remap the grey values for each tiles.</param>
/// <param name="cdfY">The Y index of the lookup table to use.</param> /// <param name="cdfY">The Y index of the lookup table to use.</param>
/// <param name="sourceWidth">The source image width.</param> /// <param name="sourceWidth">The source image width.</param>
@ -226,7 +220,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
/// or 65536 for 16-bit grayscale images. /// or 65536 for 16-bit grayscale images.
/// </param> /// </param>
private static void ProcessBorderRow( private static void ProcessBorderRow(
ref TPixel pixelBase, ImageFrame<TPixel> source,
CdfTileData cdfData, CdfTileData cdfData,
int cdfY, int cdfY,
int sourceWidth, int sourceWidth,
@ -244,12 +238,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
{ {
for (int dy = yStart; dy < yEnd; dy++) for (int dy = yStart; dy < yEnd; dy++)
{ {
int dyOffSet = dy * sourceWidth; Span<TPixel> rowSpan = source.GetPixelRowSpan(dy);
int tileX = 0; int tileX = 0;
int xLimit = Math.Min(x + tileWidth, sourceWidth - 1); int xLimit = Math.Min(x + tileWidth, sourceWidth - 1);
for (int dx = x; dx < xLimit; dx++) for (int dx = x; dx < xLimit; dx++)
{ {
ref TPixel pixel = ref Unsafe.Add(ref pixelBase, dyOffSet + dx); ref TPixel pixel = ref rowSpan[dx];
float luminanceEqualized = InterpolateBetweenTwoTiles(pixel, cdfData, cdfX, cdfY, cdfX + 1, cdfY, tileX, tileWidth, luminanceLevels); float luminanceEqualized = InterpolateBetweenTwoTiles(pixel, cdfData, cdfX, cdfY, cdfX + 1, cdfY, tileX, tileWidth, luminanceLevels);
pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W)); pixel.FromVector4(new Vector4(luminanceEqualized, luminanceEqualized, luminanceEqualized, pixel.ToVector4().W));
tileX++; tileX++;
@ -410,8 +404,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
[MethodImpl(InliningOptions.ShortMethod)] [MethodImpl(InliningOptions.ShortMethod)]
public void Invoke(in RowInterval rows) public void Invoke(in RowInterval rows)
{ {
ref TPixel sourceBase = ref this.source.GetPixelReference(0, 0);
for (int index = rows.Min; index < rows.Max; index++) for (int index = rows.Min; index < rows.Max; index++)
{ {
(int y, int cdfY) tileYStartPosition = this.tileYStartPositions[index]; (int y, int cdfY) tileYStartPosition = this.tileYStartPositions[index];
@ -427,11 +419,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
int xEnd = Math.Min(x + this.tileWidth, this.sourceWidth); int xEnd = Math.Min(x + this.tileWidth, this.sourceWidth);
for (int dy = y; dy < yEnd; dy++) for (int dy = y; dy < yEnd; dy++)
{ {
int dyOffSet = dy * this.sourceWidth; Span<TPixel> rowSpan = this.source.GetPixelRowSpan(dy);
int tileX = 0; int tileX = 0;
for (int dx = x; dx < xEnd; dx++) for (int dx = x; dx < xEnd; dx++)
{ {
ref TPixel pixel = ref Unsafe.Add(ref sourceBase, dyOffSet + dx); ref TPixel pixel = ref rowSpan[dx];
float luminanceEqualized = InterpolateBetweenFourTiles( float luminanceEqualized = InterpolateBetweenFourTiles(
pixel, pixel,
this.cdfData, this.cdfData,
@ -597,15 +589,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
[MethodImpl(InliningOptions.ShortMethod)] [MethodImpl(InliningOptions.ShortMethod)]
public void Invoke(in RowInterval rows) public void Invoke(in RowInterval rows)
{ {
ref TPixel sourceBase = ref this.source.GetPixelReference(0, 0);
for (int index = rows.Min; index < rows.Max; index++) for (int index = rows.Min; index < rows.Max; index++)
{ {
int cdfX = 0; int cdfX = 0;
int cdfY = this.tileYStartPositions[index].cdfY; int cdfY = this.tileYStartPositions[index].cdfY;
int y = this.tileYStartPositions[index].y; int y = this.tileYStartPositions[index].y;
int endY = Math.Min(y + this.tileHeight, this.sourceHeight); int endY = Math.Min(y + this.tileHeight, this.sourceHeight);
ref int cdfMinBase = ref MemoryMarshal.GetReference(this.cdfMinBuffer2D.GetRowSpan(cdfY)); Span<int> cdfMinSpan = this.cdfMinBuffer2D.GetRowSpan(cdfY);
using IMemoryOwner<int> histogramBuffer = this.allocator.Allocate<int>(this.luminanceLevels); using IMemoryOwner<int> histogramBuffer = this.allocator.Allocate<int>(this.luminanceLevels);
Span<int> histogram = histogramBuffer.GetSpan(); Span<int> histogram = histogramBuffer.GetSpan();
@ -620,10 +610,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
int xlimit = Math.Min(x + this.tileWidth, this.sourceWidth); int xlimit = Math.Min(x + this.tileWidth, this.sourceWidth);
for (int dy = y; dy < endY; dy++) for (int dy = y; dy < endY; dy++)
{ {
int dyOffset = dy * this.sourceWidth; Span<TPixel> rowSpan = this.source.GetPixelRowSpan(dy);
for (int dx = x; dx < xlimit; dx++) for (int dx = x; dx < xlimit; dx++)
{ {
int luminance = GetLuminance(Unsafe.Add(ref sourceBase, dyOffset + dx), this.luminanceLevels); int luminance = GetLuminance(rowSpan[dx], this.luminanceLevels);
histogram[luminance]++; histogram[luminance]++;
} }
} }
@ -633,7 +623,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
this.processor.ClipHistogram(histogram, this.processor.ClipLimit); this.processor.ClipHistogram(histogram, this.processor.ClipLimit);
} }
Unsafe.Add(ref cdfMinBase, cdfX) = this.processor.CalculateCdf(ref cdfBase, ref histogramBase, histogram.Length - 1); cdfMinSpan[cdfX] += this.processor.CalculateCdf(ref cdfBase, ref histogramBase, histogram.Length - 1);
cdfX++; cdfX++;
} }

8
src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs
View File

@ -116,13 +116,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
public void Invoke(int y) public void Invoke(int y)
{ {
ref int histogramBase = ref MemoryMarshal.GetReference(this.histogramBuffer.GetSpan()); ref int histogramBase = ref MemoryMarshal.GetReference(this.histogramBuffer.GetSpan());
ref TPixel pixelBase = ref MemoryMarshal.GetReference(this.source.GetPixelRowSpan(y)); Span<TPixel> pixelRow = this.source.GetPixelRowSpan(y);
int levels = this.luminanceLevels; int levels = this.luminanceLevels;
for (int x = 0; x < this.bounds.Width; x++) for (int x = 0; x < this.bounds.Width; x++)
{ {
// TODO: We should bulk convert here. // TODO: We should bulk convert here.
var vector = Unsafe.Add(ref pixelBase, x).ToVector4(); var vector = pixelRow[x].ToVector4();
int luminance = ImageMaths.GetBT709Luminance(ref vector, levels); int luminance = ImageMaths.GetBT709Luminance(ref vector, levels);
Interlocked.Increment(ref Unsafe.Add(ref histogramBase, luminance)); Interlocked.Increment(ref Unsafe.Add(ref histogramBase, luminance));
} }
@ -165,14 +165,14 @@ namespace SixLabors.ImageSharp.Processing.Processors.Normalization
public void Invoke(int y) public void Invoke(int y)
{ {
ref int cdfBase = ref MemoryMarshal.GetReference(this.cdfBuffer.GetSpan()); ref int cdfBase = ref MemoryMarshal.GetReference(this.cdfBuffer.GetSpan());
ref TPixel pixelBase = ref MemoryMarshal.GetReference(this.source.GetPixelRowSpan(y)); Span<TPixel> pixelRow = this.source.GetPixelRowSpan(y);
int levels = this.luminanceLevels; int levels = this.luminanceLevels;
float noOfPixelsMinusCdfMin = this.numberOfPixelsMinusCdfMin; float noOfPixelsMinusCdfMin = this.numberOfPixelsMinusCdfMin;
for (int x = 0; x < this.bounds.Width; x++) for (int x = 0; x < this.bounds.Width; x++)
{ {
// TODO: We should bulk convert here. // TODO: We should bulk convert here.
ref TPixel pixel = ref Unsafe.Add(ref pixelBase, x); ref TPixel pixel = ref pixelRow[x];
var vector = pixel.ToVector4(); var vector = pixel.ToVector4();
int luminance = ImageMaths.GetBT709Luminance(ref vector, levels); int luminance = ImageMaths.GetBT709Luminance(ref vector, levels);
float luminanceEqualized = Unsafe.Add(ref cdfBase, luminance) / noOfPixelsMinusCdfMin; float luminanceEqualized = Unsafe.Add(ref cdfBase, luminance) / noOfPixelsMinusCdfMin;

53
tests/ImageSharp.Benchmarks/Processing/HistogramEqualization.cs
View File

@ -0,0 +1,53 @@
// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.
using System.IO;
using BenchmarkDotNet.Attributes;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.Processing.Processors.Normalization;
using SixLabors.ImageSharp.Tests;
namespace SixLabors.ImageSharp.Benchmarks.Processing
{
[Config(typeof(Config.ShortClr))]
public class HistogramEqualization : BenchmarkBase
{
private Image<Rgba32> image;
[GlobalSetup]
public void ReadImages()
{
if (this.image == null)
{
this.image = Image.Load<Rgba32>(File.OpenRead(Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, TestImages.Jpeg.Baseline.HistogramEqImage)));
}
}
[GlobalCleanup]
public void Cleanup()
{
this.image.Dispose();
}
[Benchmark(Description = "Global Histogram Equalization")]
public void GlobalHistogramEqualization()
{
this.image.Mutate(img => img.HistogramEqualization(new HistogramEqualizationOptions()
{
LuminanceLevels = 256,
Method = HistogramEqualizationMethod.Global
}));
}
[Benchmark(Description = "AdaptiveHistogramEqualization (Tile interpolation)")]
public void AdaptiveHistogramEqualization()
{
this.image.Mutate(img => img.HistogramEqualization(new HistogramEqualizationOptions()
{
LuminanceLevels = 256,
Method = HistogramEqualizationMethod.AdaptiveTileInterpolation
}));
}
}
}
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