mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
7 years ago
18 changed files with 545 additions and 221 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 System; |
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using System.Runtime.CompilerServices; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Processing.Processors.Dithering; |
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namespace SixLabors.ImageSharp.Processing.Processors.Quantization |
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{ |
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/// <summary>
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/// A generic palette quantizer.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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public class PaletteQuantizer<TPixel> : IQuantizer |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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private readonly TPixel[] palette; |
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/// <summary>
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/// Initializes a new instance of the <see cref="PaletteQuantizer{TPixel}"/> class.
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/// </summary>
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/// <param name="palette">The color palette to use.</param>
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public PaletteQuantizer(TPixel[] palette) |
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: this(palette, true) |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="PaletteQuantizer{TPixel}"/> class.
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/// </summary>
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/// <param name="palette">The color palette to use.</param>
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/// <param name="dither">Whether to apply dithering to the output image</param>
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public PaletteQuantizer(TPixel[] palette, bool dither) |
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: this(palette, GetDiffuser(dither)) |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="PaletteQuantizer{TPixel}"/> class.
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/// </summary>
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/// <param name="palette">The color palette to use.</param>
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/// <param name="diffuser">The error diffusion algorithm, if any, to apply to the output image</param>
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public PaletteQuantizer(TPixel[] palette, IErrorDiffuser diffuser) |
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{ |
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Guard.MustBeBetweenOrEqualTo(palette.Length, QuantizerConstants.MinColors, QuantizerConstants.MaxColors, nameof(palette)); |
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this.palette = palette; |
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this.Diffuser = diffuser; |
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} |
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/// <inheritdoc/>
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public IErrorDiffuser Diffuser { get; } |
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/// <inheritdoc/>
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public IFrameQuantizer<TPixel1> CreateFrameQuantizer<TPixel1>() |
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where TPixel1 : struct, IPixel<TPixel1> |
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{ |
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if (!typeof(TPixel).Equals(typeof(TPixel1))) |
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{ |
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throw new InvalidOperationException("Generic method type must be the same as class type."); |
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} |
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TPixel[] paletteRef = this.palette; |
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return new PaletteFrameQuantizer<TPixel1>(this, Unsafe.As<TPixel[], TPixel1[]>(ref paletteRef)); |
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} |
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/// <inheritdoc/>
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public IFrameQuantizer<TPixel1> CreateFrameQuantizer<TPixel1>(int maxColors) |
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where TPixel1 : struct, IPixel<TPixel1> |
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{ |
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if (!typeof(TPixel).Equals(typeof(TPixel1))) |
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{ |
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throw new InvalidOperationException("Generic method type must be the same as class type."); |
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} |
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TPixel[] paletteRef = this.palette; |
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TPixel1[] castPalette = Unsafe.As<TPixel[], TPixel1[]>(ref paletteRef); |
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maxColors = maxColors.Clamp(QuantizerConstants.MinColors, QuantizerConstants.MaxColors); |
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int max = Math.Min(maxColors, castPalette.Length); |
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if (max != castPalette.Length) |
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{ |
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return new PaletteFrameQuantizer<TPixel1>(this, castPalette.AsSpan(0, max).ToArray()); |
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} |
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return new PaletteFrameQuantizer<TPixel1>(this, castPalette); |
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} |
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private static IErrorDiffuser GetDiffuser(bool dither) => dither ? KnownDiffusers.FloydSteinberg : null; |
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} |
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} |
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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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namespace SixLabors.ImageSharp.Processing.Processors.Quantization |
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{ |
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/// <summary>
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/// Contains color quantization specific constants.
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/// </summary>
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internal static class QuantizerConstants |
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{ |
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/// <summary>
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/// The minimum number of colors to use when quantizing an image.
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/// </summary>
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public const int MinColors = 1; |
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/// <summary>
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/// The maximum number of colors to use when quantizing an image.
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/// </summary>
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public const int MaxColors = 256; |
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} |
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} |
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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.Dithering; |
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namespace SixLabors.ImageSharp.Processing.Processors.Quantization |
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{ |
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/// <summary>
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/// A palette quantizer consisting of web safe colors as defined in the CSS Color Module Level 4.
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/// </summary>
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public class WebSafePaletteQuantizer : PaletteQuantizer |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="WebSafePaletteQuantizer" /> class.
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/// </summary>
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public WebSafePaletteQuantizer() |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="WebSafePaletteQuantizer" /> class.
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/// </summary>
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/// <param name="dither">Whether to apply dithering to the output image</param>
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public WebSafePaletteQuantizer(bool dither) |
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: base(dither) |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="WebSafePaletteQuantizer" /> class.
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/// </summary>
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/// <param name="diffuser">The error diffusion algorithm, if any, to apply to the output image</param>
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public WebSafePaletteQuantizer(IErrorDiffuser diffuser) |
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: base(diffuser) |
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{ |
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} |
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/// <inheritdoc />
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public override IFrameQuantizer<TPixel> CreateFrameQuantizer<TPixel>() |
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=> this.CreateFrameQuantizer<TPixel>(NamedColors<TPixel>.WebSafePalette.Length); |
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/// <inheritdoc/>
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public override IFrameQuantizer<TPixel> CreateFrameQuantizer<TPixel>(int maxColors) |
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=> this.CreateFrameQuantizer(NamedColors<TPixel>.WebSafePalette, maxColors); |
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} |
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} |
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@ -0,0 +1,48 @@ |
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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.Dithering; |
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namespace SixLabors.ImageSharp.Processing.Processors.Quantization |
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{ |
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/// <summary>
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/// A palette quantizer consisting of colors as defined in the original second edition of Werner’s Nomenclature of Colours 1821.
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/// The hex codes were collected and defined by Nicholas Rougeux <see href="https://www.c82.net/werner"/>
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/// </summary>
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public class WernerPaletteQuantizer : PaletteQuantizer |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="WernerPaletteQuantizer" /> class.
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/// </summary>
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public WernerPaletteQuantizer() |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="WernerPaletteQuantizer" /> class.
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/// </summary>
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/// <param name="dither">Whether to apply dithering to the output image</param>
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public WernerPaletteQuantizer(bool dither) |
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: base(dither) |
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{ |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="WernerPaletteQuantizer" /> class.
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/// </summary>
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/// <param name="diffuser">The error diffusion algorithm, if any, to apply to the output image</param>
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public WernerPaletteQuantizer(IErrorDiffuser diffuser) |
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: base(diffuser) |
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{ |
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} |
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/// <inheritdoc />
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public override IFrameQuantizer<TPixel> CreateFrameQuantizer<TPixel>() |
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=> this.CreateFrameQuantizer<TPixel>(NamedColors<TPixel>.WernerPalette.Length); |
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/// <inheritdoc/>
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public override IFrameQuantizer<TPixel> CreateFrameQuantizer<TPixel>(int maxColors) |
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=> this.CreateFrameQuantizer(NamedColors<TPixel>.WernerPalette, maxColors); |
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} |
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} |
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