mirror of https://github.com/SixLabors/ImageSharp
Anton Firszov
7 years ago
7 changed files with 180 additions and 141 deletions
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Processing.Processors.Convolution; |
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using SixLabors.Primitives; |
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namespace SixLabors.ImageSharp.Processing |
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{ |
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/// <summary>
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/// Adds Gaussian sharpening extensions to the <see cref="Image{TPixel}"/> type.
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/// Adds Gaussian sharpening extensions to the <see cref="Image"/> type.
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/// </summary>
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public static class GaussianSharpenExtensions |
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{ |
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/// <summary>
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/// Applies a Gaussian sharpening filter to the image.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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/// <param name="source">The image this method extends.</param>
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/// <returns>The <see cref="Image{TPixel}"/>.</returns>
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public static IImageProcessingContext<TPixel> GaussianSharpen<TPixel>(this IImageProcessingContext<TPixel> source) |
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where TPixel : struct, IPixel<TPixel> |
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=> source.ApplyProcessor(new GaussianSharpenProcessor<TPixel>()); |
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public static IImageProcessingContext GaussianSharpen(this IImageProcessingContext source) => |
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source.ApplyProcessor(new GaussianSharpenProcessor()); |
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/// <summary>
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/// Applies a Gaussian sharpening filter to the image.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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/// <param name="source">The image this method extends.</param>
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/// <param name="sigma">The 'sigma' value representing the weight of the blur.</param>
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/// <returns>The <see cref="Image{TPixel}"/>.</returns>
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public static IImageProcessingContext<TPixel> GaussianSharpen<TPixel>(this IImageProcessingContext<TPixel> source, float sigma) |
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where TPixel : struct, IPixel<TPixel> |
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=> source.ApplyProcessor(new GaussianSharpenProcessor<TPixel>(sigma)); |
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public static IImageProcessingContext GaussianSharpen(this IImageProcessingContext source, float sigma) => |
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source.ApplyProcessor(new GaussianSharpenProcessor(sigma)); |
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/// <summary>
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/// Applies a Gaussian sharpening filter to the image.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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/// <param name="source">The image this method extends.</param>
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/// <param name="sigma">The 'sigma' value representing the weight of the blur.</param>
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/// <param name="rectangle">
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/// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
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/// </param>
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/// <returns>The <see cref="Image{TPixel}"/>.</returns>
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public static IImageProcessingContext<TPixel> GaussianSharpen<TPixel>(this IImageProcessingContext<TPixel> source, float sigma, Rectangle rectangle) |
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where TPixel : struct, IPixel<TPixel> |
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=> source.ApplyProcessor(new GaussianSharpenProcessor<TPixel>(sigma), rectangle); |
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public static IImageProcessingContext GaussianSharpen( |
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this IImageProcessingContext source, |
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float sigma, |
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Rectangle rectangle) => |
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source.ApplyProcessor(new GaussianSharpenProcessor(sigma), rectangle); |
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} |
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} |
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} |
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@ -0,0 +1,93 @@ |
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// // Copyright (c) Six Labors and contributors.
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// // Licensed under the Apache License, Version 2.0.
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using System; |
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using SixLabors.ImageSharp.Primitives; |
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namespace SixLabors.ImageSharp.Processing.Processors.Convolution |
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{ |
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internal static class ConvolutionProcessorHelpers |
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{ |
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/// <summary>
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/// Kernel radius is calculated using the minimum viable value.
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/// <see cref="http://chemaguerra.com/gaussian-filter-radius/"/>.
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/// </summary>
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internal static int GetDefaultGaussianRadius(float sigma) |
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{ |
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return (int)MathF.Ceiling(sigma * 3); |
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} |
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/// <summary>
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/// Create a 1 dimensional Gaussian kernel using the Gaussian G(x) function
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/// </summary>
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/// <returns>The <see cref="DenseMatrix{T}"/>.</returns>
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internal static DenseMatrix<float> CreateGaussianBlurKernel(int size, float weight) |
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{ |
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var kernel = new DenseMatrix<float>(size, 1); |
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float sum = 0F; |
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float midpoint = (size - 1) / 2F; |
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for (int i = 0; i < size; i++) |
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{ |
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float x = i - midpoint; |
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float gx = ImageMaths.Gaussian(x, weight); |
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sum += gx; |
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kernel[0, i] = gx; |
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} |
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// Normalize kernel so that the sum of all weights equals 1
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for (int i = 0; i < size; i++) |
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{ |
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kernel[0, i] /= sum; |
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} |
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return kernel; |
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} |
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/// <summary>
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/// Create a 1 dimensional Gaussian kernel using the Gaussian G(x) function
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/// </summary>
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/// <returns>The <see cref="DenseMatrix{T}"/>.</returns>
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internal static DenseMatrix<float> CreateGaussianSharpenKernel(int size, float weight) |
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{ |
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var kernel = new DenseMatrix<float>(size, 1); |
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float sum = 0; |
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float midpoint = (size - 1) / 2F; |
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for (int i = 0; i < size; i++) |
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{ |
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float x = i - midpoint; |
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float gx = ImageMaths.Gaussian(x, weight); |
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sum += gx; |
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kernel[0, i] = gx; |
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} |
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// Invert the kernel for sharpening.
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int midpointRounded = (int)midpoint; |
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for (int i = 0; i < size; i++) |
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{ |
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if (i == midpointRounded) |
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{ |
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// Calculate central value
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kernel[0, i] = (2F * sum) - kernel[0, i]; |
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} |
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else |
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{ |
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// invert value
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kernel[0, i] = -kernel[0, i]; |
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} |
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} |
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// Normalize kernel so that the sum of all weights equals 1
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for (int i = 0; i < size; i++) |
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{ |
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kernel[0, i] /= sum; |
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} |
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return kernel; |
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} |
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} |
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} |
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@ -0,0 +1,42 @@ |
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Primitives; |
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using SixLabors.Primitives; |
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namespace SixLabors.ImageSharp.Processing.Processors.Convolution |
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{ |
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/// <summary>
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/// Applies Gaussian sharpening processing to the image.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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internal class GaussianSharpenProcessor<TPixel> : ImageProcessor<TPixel> |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="GaussianSharpenProcessor{TPixel}"/> class.
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/// </summary>
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/// <param name="definition">The <see cref="GaussianBlurProcessor"/> defining the processor parameters.</param>
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public GaussianSharpenProcessor(GaussianSharpenProcessor definition) |
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{ |
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int kernelSize = (definition.Radius * 2) + 1; |
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this.KernelX = ConvolutionProcessorHelpers.CreateGaussianSharpenKernel(kernelSize, definition.Sigma); |
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this.KernelY = this.KernelX.Transpose(); |
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} |
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/// <summary>
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/// Gets the horizontal gradient operator.
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/// </summary>
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public DenseMatrix<float> KernelX { get; } |
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/// <summary>
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/// Gets the vertical gradient operator.
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/// </summary>
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public DenseMatrix<float> KernelY { get; } |
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/// <inheritdoc/>
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protected override void OnFrameApply(ImageFrame<TPixel> source, Rectangle sourceRectangle, Configuration configuration) |
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=> new Convolution2PassProcessor<TPixel>(this.KernelX, this.KernelY, false).Apply(source, sourceRectangle, configuration); |
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} |
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} |
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