/// <summary>
/// Rotates the image 90 degrees clockwise at the centre point.
/// </summary>
/// <param name="source">The source image.</param>
/// <param name="destination">The destination image.</param>
/// <param name="configuration">The configuration.</param>
private void Rotate90(ImageFrame <TPixel> source, ImageFrame <TPixel> destination, Configuration configuration)
{
int width = source.Width;
int height = source.Height;
Rectangle destinationBounds = destination.Bounds();
ParallelHelper.IterateRows(
source.Bounds(),
configuration,
rows =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
Span <TPixel> sourceRow = source.GetPixelRowSpan(y);
int newX = height - y - 1;
for (int x = 0; x < width; x++)
{
// TODO: Optimize this:
if (destinationBounds.Contains(newX, x))
{
destination[newX, x] = sourceRow[x];
}
}
}
});
}
/// <inheritdoc/>
protected override void OnApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
float threshold = this.Threshold * 255F;
TPixel upper = this.UpperColor;
TPixel lower = this.LowerColor;
var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
int startY = interest.Y;
int endY = interest.Bottom;
int startX = interest.X;
int endX = interest.Right;
bool isAlphaOnly = typeof(TPixel) == typeof(Alpha8);
Parallel.For(
startY,
endY,
configuration.ParallelOptions,
y =>
{
Span <TPixel> row = source.GetPixelRowSpan(y);
var rgba = default(Rgba32);
for (int x = startX; x < endX; x++)
{
ref TPixel color = ref row[x];
color.ToRgba32(ref rgba);
// Convert to grayscale using ITU-R Recommendation BT.709 if required
float luminance = isAlphaOnly ? rgba.A : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B);
color = luminance >= threshold ? upper : lower;
}
});
}
/// <summary>
/// Creates the quantized frame.
/// </summary>
/// <typeparam name="TPixel">The type of the pixel.</typeparam>
/// <param name="options">The options.</param>
/// <param name="image">The image.</param>
public static IndexedImageFrame <TPixel> CreateQuantizedFrame <TPixel>(
PngEncoderOptions options,
Image <TPixel> image)
where TPixel : unmanaged, IPixel <TPixel>
{
if (options.ColorType != PngColorType.Palette)
{
return(null);
}
byte bits = (byte)options.BitDepth;
if (Array.IndexOf(PngConstants.ColorTypes[options.ColorType.Value], bits) == -1)
{
throw new NotSupportedException("Bit depth is not supported or not valid.");
}
// Use the metadata to determine what quantization depth to use if no quantizer has been set.
if (options.Quantizer is null)
{
var maxColors = ImageMaths.GetColorCountForBitDepth(bits);
options.Quantizer = new WuQuantizer(new QuantizerOptions {
MaxColors = maxColors
});
}
// Create quantized frame returning the palette and set the bit depth.
using (IFrameQuantizer <TPixel> frameQuantizer = options.Quantizer.CreateFrameQuantizer <TPixel>(image.GetConfiguration()))
{
ImageFrame <TPixel> frame = image.Frames.RootFrame;
return(frameQuantizer.QuantizeFrame(frame, frame.Bounds()));
}
}
public TiffPaletteWriter(
ImageFrame <TPixel> image,
IQuantizer quantizer,
MemoryAllocator memoryAllocator,
Configuration configuration,
TiffEncoderEntriesCollector entriesCollector,
int bitsPerPixel)
: base(image, memoryAllocator, configuration, entriesCollector)
{
DebugGuard.NotNull(quantizer, nameof(quantizer));
DebugGuard.NotNull(configuration, nameof(configuration));
DebugGuard.NotNull(entriesCollector, nameof(entriesCollector));
DebugGuard.MustBeBetweenOrEqualTo(bitsPerPixel, 4, 8, nameof(bitsPerPixel));
this.BitsPerPixel = bitsPerPixel;
this.maxColors = this.BitsPerPixel == 4 ? 16 : 256;
this.colorPaletteSize = this.maxColors * 3;
this.colorPaletteBytes = this.colorPaletteSize * 2;
using IQuantizer <TPixel> frameQuantizer = quantizer.CreatePixelSpecificQuantizer <TPixel>(this.Configuration, new QuantizerOptions()
{
MaxColors = this.maxColors
});
this.quantizedImage = frameQuantizer.BuildPaletteAndQuantizeFrame(image, image.Bounds());
this.AddColorMapTag();
}
/// <summary>
/// Rotates the image 270 degrees clockwise at the centre point.
/// </summary>
/// <param name="source">The source image.</param>
/// <param name="destination">The destination image.</param>
/// <param name="configuration">The configuration.</param>
private void Rotate270(ImageFrame <TPixel> source, ImageFrame <TPixel> destination, Configuration configuration)
{
int width = source.Width;
int height = source.Height;
Rectangle destinationBounds = destination.Bounds();
Parallel.For(
0,
height,
configuration.ParallelOptions,
y =>
{
Span <TPixel> sourceRow = source.GetPixelRowSpan(y);
for (int x = 0; x < width; x++)
{
int newX = height - y - 1;
newX = height - newX - 1;
int newY = width - x - 1;
if (destinationBounds.Contains(newX, newY))
{
destination[newX, newY] = sourceRow[x];
}
}
});
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
int startX = interest.X;
ColorMatrix matrix = this.definition.Matrix;
ParallelHelper.IterateRowsWithTempBuffer <Vector4>(
interest,
configuration,
(rows, vectorBuffer) =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
Span <Vector4> vectorSpan = vectorBuffer.Span;
int length = vectorSpan.Length;
Span <TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
PixelOperations <TPixel> .Instance.ToVector4(configuration, rowSpan, vectorSpan);
Vector4Utils.Transform(vectorSpan, ref matrix);
PixelOperations <TPixel> .Instance.FromVector4Destructive(configuration, vectorSpan, rowSpan);
}
});
}
/// <inheritdoc/>
protected override void OnApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
int height = this.CanvasRectangle.Height;
int width = this.CanvasRectangle.Width;
Matrix3x2 matrix = this.GetCenteredMatrix(source, this.processMatrix);
Rectangle sourceBounds = source.Bounds();
using (var targetPixels = new PixelAccessor <TPixel>(width, height))
{
Parallel.For(
0,
height,
configuration.ParallelOptions,
y =>
{
Span <TPixel> targetRow = targetPixels.GetRowSpan(y);
for (int x = 0; x < width; x++)
{
var transformedPoint = Point.Skew(new Point(x, y), matrix);
if (sourceBounds.Contains(transformedPoint.X, transformedPoint.Y))
{
targetRow[x] = source[transformedPoint.X, transformedPoint.Y];
}
}
});
source.SwapPixelsBuffers(targetPixels);
}
}
/// <summary>
/// Creates the quantized frame.
/// </summary>
/// <typeparam name="TPixel">The type of the pixel.</typeparam>
/// <param name="options">The options.</param>
/// <param name="image">The image.</param>
public static IndexedImageFrame <TPixel> CreateQuantizedFrame <TPixel>(
PngEncoderOptions options,
Image <TPixel> image)
where TPixel : unmanaged, IPixel <TPixel>
{
if (options.ColorType != PngColorType.Palette)
{
return(null);
}
// Use the metadata to determine what quantization depth to use if no quantizer has been set.
if (options.Quantizer is null)
{
byte bits = (byte)options.BitDepth;
var maxColors = ImageMaths.GetColorCountForBitDepth(bits);
options.Quantizer = new WuQuantizer(new QuantizerOptions {
MaxColors = maxColors
});
}
// Create quantized frame returning the palette and set the bit depth.
using (IQuantizer <TPixel> frameQuantizer = options.Quantizer.CreatePixelSpecificQuantizer <TPixel>(image.GetConfiguration()))
{
ImageFrame <TPixel> frame = image.Frames.RootFrame;
return(frameQuantizer.BuildPaletteAndQuantizeFrame(frame, frame.Bounds()));
}
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
TPixel glowColor = this.definition.GlowColor.ToPixel <TPixel>();
float blendPercent = this.definition.GraphicsOptions.BlendPercentage;
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
Vector2 center = Rectangle.Center(interest);
float finalRadius = this.definition.Radius.Calculate(interest.Size);
float maxDistance = finalRadius > 0
? MathF.Min(finalRadius, interest.Width * .5F)
: interest.Width * .5F;
Configuration configuration = this.Configuration;
MemoryAllocator allocator = configuration.MemoryAllocator;
using IMemoryOwner <TPixel> rowColors = allocator.Allocate <TPixel>(interest.Width);
rowColors.GetSpan().Fill(glowColor);
var operation = new RowOperation(configuration, interest, rowColors, this.blender, center, maxDistance, blendPercent, source);
ParallelRowIterator.IterateRows <RowOperation, float>(
configuration,
interest,
in operation);
}
/// <inheritdoc />
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
// We need a clean copy for each pass to start from
using ImageFrame <TPixel> cleanCopy = source.Clone();
using (var processor = new ConvolutionProcessor <TPixel>(this.Configuration, in this.kernels[0], true, this.Source, interest))
{
processor.Apply(source);
}
if (this.kernels.Length == 1)
{
return;
}
// Additional runs
for (int i = 1; i < this.kernels.Length; i++)
{
using ImageFrame <TPixel> pass = cleanCopy.Clone();
using (var processor = new ConvolutionProcessor <TPixel>(this.Configuration, in this.kernels[i], true, this.Source, interest))
{
processor.Apply(pass);
}
var operation = new RowOperation(source.PixelBuffer, pass.PixelBuffer, interest);
ParallelRowIterator.IterateRows(
this.Configuration,
interest,
in operation);
}
}
/// <inheritdoc />
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(source.Bounds(), this.SourceRectangle);
Configuration configuration = this.Configuration;
using IQuantizer <TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer <TPixel>(configuration);
using IndexedImageFrame <TPixel> quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(source, interest);
ReadOnlySpan <TPixel> paletteSpan = quantized.Palette.Span;
int offsetY = interest.Top;
int offsetX = interest.Left;
Buffer2D <TPixel> sourceBuffer = source.PixelBuffer;
for (int y = interest.Y; y < interest.Height; y++)
{
Span <TPixel> row = sourceBuffer.DangerousGetRowSpan(y);
ReadOnlySpan <byte> quantizedRow = quantized.DangerousGetRowSpan(y - offsetY);
for (int x = interest.Left; x < interest.Right; x++)
{
row[x] = paletteSpan[quantizedRow[x - offsetX]];
}
}
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
int startY = interest.Y;
int endY = interest.Bottom;
int startX = interest.X;
int endX = interest.Right;
Matrix4x4 matrix = this.Matrix;
ParallelFor.WithConfiguration(
startY,
endY,
configuration,
y =>
{
Span <TPixel> row = source.GetPixelRowSpan(y);
for (int x = startX; x < endX; x++)
{
ref TPixel pixel = ref row[x];
var vector = Vector4.Transform(pixel.ToVector4(), matrix);
pixel.PackFromVector4(vector);
}
});
}
/// <summary>
/// Quantizes an image frame and return the resulting output pixels.
/// </summary>
/// <typeparam name="TFrameQuantizer">The type of frame quantizer.</typeparam>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="quantizer">The frame </param>
/// <param name="source">The source image frame to quantize.</param>
/// <param name="bounds">The bounds within the frame to quantize.</param>
/// <returns>
/// A <see cref="QuantizedFrame{TPixel}"/> representing a quantized version of the source frame pixels.
/// </returns>
public static QuantizedFrame <TPixel> QuantizeFrame <TFrameQuantizer, TPixel>(
ref TFrameQuantizer quantizer,
ImageFrame <TPixel> source,
Rectangle bounds)
where TFrameQuantizer : struct, IFrameQuantizer <TPixel>
where TPixel : unmanaged, IPixel <TPixel>
{
Guard.NotNull(source, nameof(source));
var interest = Rectangle.Intersect(source.Bounds(), bounds);
// Collect the palette. Required before the second pass runs.
ReadOnlyMemory <TPixel> palette = quantizer.BuildPalette(source, interest);
MemoryAllocator memoryAllocator = quantizer.Configuration.MemoryAllocator;
var quantizedFrame = new QuantizedFrame <TPixel>(memoryAllocator, interest.Width, interest.Height, palette);
Memory <byte> output = quantizedFrame.GetWritablePixelMemory();
if (quantizer.Options.Dither is null)
{
SecondPass(ref quantizer, source, interest, output, palette);
}
else
{
// We clone the image as we don't want to alter the original via error diffusion based dithering.
using (ImageFrame <TPixel> clone = source.Clone())
{
SecondPass(ref quantizer, clone, interest, output, palette);
}
}
return(quantizedFrame);
}
private void EncodeLocal <TPixel>(Image <TPixel> image, IndexedImageFrame <TPixel> quantized, Stream stream)
where TPixel : unmanaged, IPixel <TPixel>
{
ImageFrame <TPixel> previousFrame = null;
GifFrameMetadata previousMeta = null;
for (int i = 0; i < image.Frames.Count; i++)
{
ImageFrame <TPixel> frame = image.Frames[i];
ImageFrameMetadata metadata = frame.Metadata;
GifFrameMetadata frameMetadata = metadata.GetGifMetadata();
if (quantized is null)
{
// Allow each frame to be encoded at whatever color depth the frame designates if set.
if (previousFrame != null && previousMeta.ColorTableLength != frameMetadata.ColorTableLength &&
frameMetadata.ColorTableLength > 0)
{
var options = new QuantizerOptions
{
Dither = this.quantizer.Options.Dither,
DitherScale = this.quantizer.Options.DitherScale,
MaxColors = frameMetadata.ColorTableLength
};
using IFrameQuantizer <TPixel> frameQuantizer = this.quantizer.CreateFrameQuantizer <TPixel>(this.configuration, options);
quantized = frameQuantizer.QuantizeFrame(frame, frame.Bounds());
}
else
{
using IFrameQuantizer <TPixel> frameQuantizer = this.quantizer.CreateFrameQuantizer <TPixel>(this.configuration);
quantized = frameQuantizer.QuantizeFrame(frame, frame.Bounds());
}
}
this.bitDepth = ImageMaths.GetBitsNeededForColorDepth(quantized.Palette.Length);
this.WriteGraphicalControlExtension(frameMetadata, this.GetTransparentIndex(quantized), stream);
this.WriteImageDescriptor(frame, true, stream);
this.WriteColorTable(quantized, stream);
this.WriteImageData(quantized, stream);
quantized.Dispose();
quantized = null; // So next frame can regenerate it
previousFrame = frame;
previousMeta = frameMetadata;
}
}
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
var operation = new OpaqueRowOperation(this.Configuration, source.PixelBuffer, interest);
ParallelRowIterator.IterateRows <OpaqueRowOperation, Vector4>(this.Configuration, interest, in operation);
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
using (Buffer2D <TPixel> firstPassPixels = configuration.MemoryAllocator.Allocate2D <TPixel>(source.Size()))
{
this.ApplyConvolution(firstPassPixels, source.PixelBuffer, source.Bounds(), this.KernelX, configuration);
this.ApplyConvolution(source.PixelBuffer, firstPassPixels, sourceRectangle, this.KernelY, configuration);
}
}
/// <summary>
/// This method pre-seeds the PaletteQuantizer in the AoT compiler for iOS.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
private static void AotCompilePaletteQuantizer <TPixel>()
where TPixel : unmanaged, IPixel <TPixel>
{
using (var test = (PaletteFrameQuantizer <TPixel>) new PaletteQuantizer(Array.Empty <Color>()).CreateFrameQuantizer <TPixel>(Configuration.Default))
{
var frame = new ImageFrame <TPixel>(Configuration.Default, 1, 1);
test.QuantizeFrame(frame, frame.Bounds());
}
}
/// <summary>
/// This method pre-seeds the WuQuantizer in the AoT compiler for iOS.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
private static void AotCompileWuQuantizer <TPixel>()
where TPixel : unmanaged, IPixel <TPixel>
{
using (var test = new WuFrameQuantizer <TPixel>(Configuration.Default, new WuQuantizer().Options))
{
var frame = new ImageFrame <TPixel>(Configuration.Default, 1, 1);
test.QuantizeFrame(frame, frame.Bounds());
}
}
/// <summary>
/// Swaps the image at the Y-axis, which goes vertically through the middle at half of the width of the image.
/// </summary>
/// <param name="source">The source image to apply the process to.</param>
/// <param name="configuration">The configuration.</param>
private void FlipY(ImageFrame <TPixel> source, Configuration configuration)
{
var operation = new RowOperation(source);
ParallelRowIterator.IterateRows(
configuration,
source.Bounds(),
in operation);
}
/// <inheritdoc/>
protected override void OnApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
ParallelOptions parallelOptions = configuration.ParallelOptions;
using (Buffer2D <TPixel> firstPassPixels = configuration.MemoryManager.Allocate2D <TPixel>(source.Size()))
{
this.ApplyConvolution(firstPassPixels, source.PixelBuffer, source.Bounds(), this.KernelX, parallelOptions);
this.ApplyConvolution(source.PixelBuffer, firstPassPixels, sourceRectangle, this.KernelY, parallelOptions);
}
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
var operation = new RowIntervalOperation(interest.X, source, this.definition.Matrix, this.Configuration);
ParallelRowIterator.IterateRows <RowIntervalOperation, Vector4>(
this.Configuration,
interest,
in operation);
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
this.dither.ApplyPaletteDither(
this.Configuration,
this.palette.Memory,
source,
interest,
this.ditherScale);
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
byte threshold = (byte)MathF.Round(this.Definition.Threshold * 255F);
bool isAlphaOnly = typeof(TPixel) == typeof(Alpha8);
var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
int startY = interest.Y;
int endY = interest.Bottom;
int startX = interest.X;
int endX = interest.Right;
// Collect the values before looping so we can reduce our calculation count for identical sibling pixels
TPixel sourcePixel = source[startX, startY];
TPixel previousPixel = sourcePixel;
PixelPair <TPixel> pair = this.GetClosestPixelPair(ref sourcePixel);
Rgba32 rgba = default;
sourcePixel.ToRgba32(ref rgba);
// Convert to grayscale using ITU-R Recommendation BT.709 if required
byte luminance = isAlphaOnly ? rgba.A : ImageMaths.Get8BitBT709Luminance(rgba.R, rgba.G, rgba.B);
for (int y = startY; y < endY; y++)
{
Span <TPixel> row = source.GetPixelRowSpan(y);
for (int x = startX; x < endX; x++)
{
sourcePixel = row[x];
// Check if this is the same as the last pixel. If so use that value
// rather than calculating it again. This is an inexpensive optimization.
if (!previousPixel.Equals(sourcePixel))
{
pair = this.GetClosestPixelPair(ref sourcePixel);
// No error to spread, exact match.
if (sourcePixel.Equals(pair.First))
{
continue;
}
sourcePixel.ToRgba32(ref rgba);
luminance = isAlphaOnly ? rgba.A : ImageMaths.Get8BitBT709Luminance(rgba.R, rgba.G, rgba.B);
// Setup the previous pointer
previousPixel = sourcePixel;
}
TPixel transformedPixel = luminance >= threshold ? pair.Second : pair.First;
this.Definition.Diffuser.Dither(source, sourcePixel, transformedPixel, x, y, startX, startY, endX, endY);
}
}
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
Rgba32 rgba = default;
bool isAlphaOnly = typeof(TPixel) == typeof(Alpha8);
var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
int startY = interest.Y;
int endY = interest.Bottom;
int startX = interest.X;
int endX = interest.Right;
// Collect the values before looping so we can reduce our calculation count for identical sibling pixels
TPixel sourcePixel = source[startX, startY];
TPixel previousPixel = sourcePixel;
PixelPair <TPixel> pair = this.GetClosestPixelPair(ref sourcePixel);
sourcePixel.ToRgba32(ref rgba);
// Convert to grayscale using ITU-R Recommendation BT.709 if required
float luminance = isAlphaOnly ? rgba.A : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B);
for (int y = startY; y < endY; y++)
{
Span <TPixel> row = source.GetPixelRowSpan(y);
for (int x = startX; x < endX; x++)
{
sourcePixel = row[x];
// Check if this is the same as the last pixel. If so use that value
// rather than calculating it again. This is an inexpensive optimization.
if (!previousPixel.Equals(sourcePixel))
{
pair = this.GetClosestPixelPair(ref sourcePixel);
// No error to spread, exact match.
if (sourcePixel.Equals(pair.First))
{
continue;
}
sourcePixel.ToRgba32(ref rgba);
luminance = isAlphaOnly ? rgba.A : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B);
// Setup the previous pointer
previousPixel = sourcePixel;
}
this.Dither.Dither(source, sourcePixel, pair.Second, pair.First, luminance, x, y);
}
}
}
/// <inheritdoc/>
protected override void OnApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
int width = source.Width;
int height = source.Height;
ParallelOptions parallelOptions = configuration.ParallelOptions;
using (var firstPassPixels = new PixelAccessor <TPixel>(width, height))
using (PixelAccessor <TPixel> sourcePixels = source.Lock())
{
this.ApplyConvolution(firstPassPixels, sourcePixels, source.Bounds(), this.KernelX, parallelOptions);
this.ApplyConvolution(sourcePixels, firstPassPixels, sourceRectangle, this.KernelY, parallelOptions);
}
}
/// <summary>
/// Swaps the image at the Y-axis, which goes vertically through the middle at half of the width of the image.
/// </summary>
/// <param name="source">The source image to apply the process to.</param>
/// <param name="configuration">The configuration.</param>
private void FlipY(ImageFrame <TPixel> source, Configuration configuration)
{
ParallelHelper.IterateRows(
source.Bounds(),
configuration,
rows =>
{
for (int y = rows.Min; y < rows.Max; y++)
{
source.GetPixelRowSpan(y).Reverse();
}
});
}
/// <summary>
/// This method pre-seeds the default dithering engine (FloydSteinbergDiffuser) in the AoT compiler for iOS.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
private static void AotCompileDithering <TPixel>()
where TPixel : unmanaged, IPixel <TPixel>
{
ErrorDither errorDither = ErrorDither.FloydSteinberg;
OrderedDither orderedDither = OrderedDither.Bayer2x2;
TPixel pixel = default;
using (var image = new ImageFrame <TPixel>(Configuration.Default, 1, 1))
{
errorDither.Dither(image, image.Bounds(), pixel, pixel, 0, 0, 0);
orderedDither.Dither(pixel, 0, 0, 0, 0);
}
}
/// <inheritdoc/>
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var intersect = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
Configuration configuration = this.Configuration;
TPixel upper = this.definition.Upper.ToPixel <TPixel>();
TPixel lower = this.definition.Lower.ToPixel <TPixel>();
float thresholdLimit = this.definition.ThresholdLimit;
int startY = intersect.Y;
int endY = intersect.Bottom;
int startX = intersect.X;
int endX = intersect.Right;
int width = intersect.Width;
int height = intersect.Height;
// ClusterSize defines the size of cluster to used to check for average. Tweaked to support up to 4k wide pixels and not more. 4096 / 16 is 256 thus the '-1'
byte clusterSize = (byte)Math.Truncate((width / 16f) - 1);
Buffer2D <TPixel> sourceBuffer = source.PixelBuffer;
// Using pooled 2d buffer for integer image table and temp memory to hold Rgb24 converted pixel data.
using (Buffer2D <ulong> intImage = this.Configuration.MemoryAllocator.Allocate2D <ulong>(width, height))
{
Rgba32 rgb = default;
for (int x = startX; x < endX; x++)
{
ulong sum = 0;
for (int y = startY; y < endY; y++)
{
Span <TPixel> row = sourceBuffer.DangerousGetRowSpan(y);
ref TPixel rowRef = ref MemoryMarshal.GetReference(row);
ref TPixel color = ref Unsafe.Add(ref rowRef, x);
color.ToRgba32(ref rgb);
sum += (ulong)(rgb.R + rgb.G + rgb.B);
if (x - startX != 0)
{
intImage[x - startX, y - startY] = intImage[x - startX - 1, y - startY] + sum;
}
else
{
intImage[x - startX, y - startY] = sum;
}
}
}
/// <inheritdoc />
protected override void OnFrameApply(ImageFrame <TPixel> source)
{
var interest = Rectangle.Intersect(source.Bounds(), this.SourceRectangle);
Configuration configuration = this.Configuration;
using IQuantizer <TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer <TPixel>(configuration);
using IndexedImageFrame <TPixel> quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(source, interest);
var operation = new RowIntervalOperation(this.SourceRectangle, source, quantized);
ParallelRowIterator.IterateRowIntervals(
configuration,
interest,
in operation);
}
/// <inheritdoc/>
protected override void OnApply(ImageFrame <TPixel> source, Rectangle sourceRectangle, Configuration configuration)
{
float threshold = this.Threshold * 255F;
var rgba = default(Rgba32);
bool isAlphaOnly = typeof(TPixel) == typeof(Alpha8);
var interest = Rectangle.Intersect(sourceRectangle, source.Bounds());
int startY = interest.Y;
int endY = interest.Bottom;
int startX = interest.X;
int endX = interest.Right;
// Collect the values before looping so we can reduce our calculation count for identical sibling pixels
TPixel sourcePixel = source[startX, startY];
TPixel previousPixel = sourcePixel;
PixelPair <TPixel> pair = this.GetClosestPixelPair(ref sourcePixel, this.Palette);
sourcePixel.ToRgba32(ref rgba);
// Convert to grayscale using ITU-R Recommendation BT.709 if required
byte luminance = (byte)(isAlphaOnly ? rgba.A : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B)).Clamp(0, 255);
for (int y = startY; y < endY; y++)
{
Span <TPixel> row = source.GetPixelRowSpan(y);
for (int x = startX; x < endX; x++)
{
sourcePixel = row[x];
// Check if this is the same as the last pixel. If so use that value
// rather than calculating it again. This is an inexpensive optimization.
if (!previousPixel.Equals(sourcePixel))
{
pair = this.GetClosestPixelPair(ref sourcePixel, this.Palette);
sourcePixel.ToRgba32(ref rgba);
luminance = (byte)(isAlphaOnly ? rgba.A : (.2126F * rgba.R) + (.7152F * rgba.G) + (.0722F * rgba.B)).Clamp(0, 255);
// Setup the previous pointer
previousPixel = sourcePixel;
}
TPixel transformedPixel = luminance >= threshold ? pair.First : pair.Second;
this.Diffuser.Dither(source, sourcePixel, transformedPixel, x, y, startX, startY, endX, endY);
}
}
}