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Optimizing Decoder 

Also adding Modulo64 and 256 to Numerics and optimizing a little bit Encoder
qoi
LuisAlfredo92 3 years ago
parent
d671006f0e
commit
02212bdd13
No known key found for this signature in database GPG Key ID: 13A8436905993B8F
3 changed files with 60 additions and 27 deletions
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  1. 25
      src/ImageSharp/Common/Helpers/Numerics.cs
  2. 46
      src/ImageSharp/Formats/Qoi/QoiDecoderCore.cs
  3. 16
      src/ImageSharp/Formats/Qoi/QoiEncoderCore.cs

25
src/ImageSharp/Common/Helpers/Numerics.cs
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@ -73,6 +73,30 @@ internal static class Numerics
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static nint Modulo8(nint x) => x & 7;
/// <summary>
/// Calculates <paramref name="x"/> % 64
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int Modulo64(int value) => value & 63;
/// <summary>
/// Calculates <paramref name="x"/> % 64
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static nint Modulo64(nint value) => value & 63;
/// <summary>
/// Calculates <paramref name="x"/> % 256
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int Modulo256(int value) => value & 255;
/// <summary>
/// Calculates <paramref name="x"/> % 256
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static nint Modulo256(nint value) => value & 255;
/// <summary>
/// Fast (x mod m) calculator, with the restriction that
/// <paramref name="m"/> should be power of 2.
@ -1039,4 +1063,5 @@ internal static class Numerics
public static nuint Vector256Count<TVector>(int length)
where TVector : struct
=> (uint)length / (uint)Vector256<TVector>.Count;
}

46
src/ImageSharp/Formats/Qoi/QoiDecoderCore.cs
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@ -3,6 +3,8 @@
using System.Buffers.Binary;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using SixLabors.ImageSharp.IO;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.Metadata;
@ -85,7 +87,7 @@ internal class QoiDecoderCore : IImageDecoderInternals
/// </summary>
/// <param name="stream">The stream where the bytes are being read</param>
/// <exception cref="InvalidImageContentException">If the stream doesn't store a qoi image</exception>
private void ProcessHeader(Stream stream)
private void ProcessHeader(BufferedReadStream stream)
{
Span<byte> magicBytes = stackalloc byte[4];
Span<byte> widthBytes = stackalloc byte[4];
@ -141,7 +143,7 @@ internal class QoiDecoderCore : IImageDecoderInternals
private static void ThrowInvalidImageContentException()
=> throw new InvalidImageContentException("The image is not a valid QOI image.");
private void ProcessPixels<TPixel>(Stream stream, Buffer2D<TPixel> pixels)
private void ProcessPixels<TPixel>(BufferedReadStream stream, Buffer2D<TPixel> pixels)
where TPixel : unmanaged, IPixel<TPixel>
{
Rgba32[] previouslySeenPixels = new Rgba32[64];
@ -151,26 +153,27 @@ internal class QoiDecoderCore : IImageDecoderInternals
// See https://github.com/phoboslab/qoi/issues/258
int pixelArrayPosition = GetArrayPosition(previousPixel);
previouslySeenPixels[pixelArrayPosition] = previousPixel;
byte operationByte;
Rgba32 readPixel = default;
Span<byte> pixelBytes = MemoryMarshal.CreateSpan(ref Unsafe.As<Rgba32, byte>(ref readPixel), 4);
TPixel pixel = default;
for (int i = 0; i < this.header.Height; i++)
{
for (int j = 0; j < this.header.Width; j++)
{
byte operationByte = (byte)stream.ReadByte();
byte[] pixelBytes;
Rgba32 readPixel;
TPixel pixel = default;
Span<TPixel> row = pixels.DangerousGetRowSpan(i);
operationByte = (byte)stream.ReadByte();
switch ((QoiChunk)operationByte)
{
// Reading one pixel with previous alpha intact
case QoiChunk.QoiOpRgb:
pixelBytes = new byte[3];
if (stream.Read(pixelBytes) < 3)
if (stream.Read(pixelBytes[..3]) < 3)
{
ThrowInvalidImageContentException();
}
readPixel = previousPixel with { R = pixelBytes[0], G = pixelBytes[1], B = pixelBytes[2] };
readPixel.A = previousPixel.A;
pixel.FromRgba32(readPixel);
pixelArrayPosition = GetArrayPosition(readPixel);
previouslySeenPixels[pixelArrayPosition] = readPixel;
@ -178,13 +181,11 @@ internal class QoiDecoderCore : IImageDecoderInternals
// Reading one pixel with new alpha
case QoiChunk.QoiOpRgba:
pixelBytes = new byte[4];
if (stream.Read(pixelBytes) < 4)
{
ThrowInvalidImageContentException();
}
readPixel = new Rgba32(pixelBytes[0], pixelBytes[1], pixelBytes[2], pixelBytes[3]);
pixel.FromRgba32(readPixel);
pixelArrayPosition = GetArrayPosition(readPixel);
previouslySeenPixels[pixelArrayPosition] = readPixel;
@ -206,9 +207,9 @@ internal class QoiDecoderCore : IImageDecoderInternals
blueDifference = (byte)(operationByte & 0b00000011);
readPixel = previousPixel with
{
R = (byte)((previousPixel.R + (redDifference - 2)) % 256),
G = (byte)((previousPixel.G + (greenDifference - 2)) % 256),
B = (byte)((previousPixel.B + (blueDifference - 2)) % 256)
R = (byte)Numerics.Modulo256(previousPixel.R + (redDifference - 2)),
G = (byte)Numerics.Modulo256(previousPixel.G + (greenDifference - 2)),
B = (byte)Numerics.Modulo256(previousPixel.B + (blueDifference - 2))
};
pixel.FromRgba32(readPixel);
pixelArrayPosition = GetArrayPosition(readPixel);
@ -219,12 +220,12 @@ internal class QoiDecoderCore : IImageDecoderInternals
// depending on the green one
case QoiChunk.QoiOpLuma:
byte diffGreen = (byte)(operationByte & 0b00111111),
currentGreen = (byte)((previousPixel.G + (diffGreen - 32)) % 256),
currentGreen = (byte)Numerics.Modulo256(previousPixel.G + (diffGreen - 32)),
nextByte = (byte)stream.ReadByte(),
diffRedDG = (byte)(nextByte >> 4),
diffBlueDG = (byte)(nextByte & 0b00001111),
currentRed = (byte)((diffRedDG - 8 + (diffGreen - 32) + previousPixel.R) % 256),
currentBlue = (byte)((diffBlueDG - 8 + (diffGreen - 32) + previousPixel.B) % 256);
currentRed = (byte)Numerics.Modulo256(diffRedDG - 8 + (diffGreen - 32) + previousPixel.R),
currentBlue = (byte)Numerics.Modulo256(diffBlueDG - 8 + (diffGreen - 32) + previousPixel.B);
readPixel = previousPixel with { R = currentRed, B = currentBlue, G = currentGreen };
pixel.FromRgba32(readPixel);
pixelArrayPosition = GetArrayPosition(readPixel);
@ -233,7 +234,7 @@ internal class QoiDecoderCore : IImageDecoderInternals
// Repeating the previous pixel 1..63 times
case QoiChunk.QoiOpRun:
byte repetitions = (byte)(operationByte & 0b00111111);
int repetitions = operationByte & 0b00111111;
if (repetitions is 62 or 63)
{
ThrowInvalidImageContentException();
@ -247,9 +248,10 @@ internal class QoiDecoderCore : IImageDecoderInternals
{
j = 0;
i++;
row = pixels.DangerousGetRowSpan(i);
}
pixels[j, i] = pixel;
row[j] = pixel;
}
j--;
@ -263,7 +265,7 @@ internal class QoiDecoderCore : IImageDecoderInternals
break;
}
pixels[j, i] = pixel;
row[j] = pixel;
previousPixel = readPixel;
}
}
@ -283,5 +285,7 @@ internal class QoiDecoderCore : IImageDecoderInternals
}
}
private static int GetArrayPosition(Rgba32 pixel) => ((pixel.R * 3) + (pixel.G * 5) + (pixel.B * 7) + (pixel.A * 11)) % 64;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int GetArrayPosition(Rgba32 pixel)
=> Numerics.Modulo64((pixel.R * 3) + (pixel.G * 5) + (pixel.B * 7) + (pixel.A * 11));
}

16
src/ImageSharp/Formats/Qoi/QoiEncoderCore.cs
View File

@ -2,6 +2,7 @@
// Licensed under the Six Labors Split License.
using System.Buffers.Binary;
using System.Runtime.CompilerServices;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.PixelFormats;
@ -63,6 +64,7 @@ public class QoiEncoderCore : IImageEncoderInternals
for (int j = 0; j < pixels.Width && i < pixels.Height; j++)
{
// We get the RGBA value from pixels
Span<TPixel> row = pixels.DangerousGetRowSpan(i);
TPixel currentPixel = pixels[j, i];
currentPixel.ToRgba32(ref currentRgba32);
@ -87,14 +89,15 @@ public class QoiEncoderCore : IImageEncoderInternals
{
j = 0;
i++;
if (i == pixels.Height)
{
break;
}
row = pixels.DangerousGetRowSpan(i);
}
if (i == pixels.Height)
{
break;
}
currentPixel = pixels[j, i];
currentPixel = row[j];
currentPixel.ToRgba32(ref currentRgba32);
}
while (currentRgba32.Equals(previousPixel) && repetitions < 62);
@ -196,6 +199,7 @@ public class QoiEncoderCore : IImageEncoderInternals
stream.WriteByte(1);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int GetArrayPosition(Rgba32 pixel)
=> ((pixel.R * 3) + (pixel.G * 5) + (pixel.B * 7) + (pixel.A * 11)) % 64;
=> Numerics.Modulo64((pixel.R * 3) + (pixel.G * 5) + (pixel.B * 7) + (pixel.A * 11));
}

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