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using System;
using Colourful.Implementation;
using Colourful.Implementation.Conversion;
using Matrix = System.Collections.Generic.IReadOnlyList<System.Collections.Generic.IReadOnlyList<double>>;
namespace Colourful.Conversion
{
/// <summary>
/// Basic implementation of the von Kries chromatic adaptation model
/// </summary>
/// <remarks>
/// Transformation described here:
/// http://www.brucelindbloom.com/index.html?Eqn_ChromAdapt.html
/// </remarks>
public sealed class VonKriesChromaticAdaptation : IChromaticAdaptation
{
private readonly IColorConversion<XYZColor, LMSColor> _conversionToLMS;
private readonly IColorConversion<LMSColor, XYZColor> _conversionToXYZ;
private Matrix _cachedDiagonalMatrix;
private XYZColor _lastSourceWhitePoint;
private XYZColor _lastTargetWhitePoint;
/// <summary>
/// Constructs von Kries chromatic adaptation using default <see cref="XYZAndLMSConverter" />
/// </summary>
public VonKriesChromaticAdaptation() : this(new XYZAndLMSConverter())
{
}
/// <summary>
/// Transformation matrix used for the conversion (definition of the cone response domain).
/// <see cref="LMSTransformationMatrix" />
/// </summary>
public VonKriesChromaticAdaptation(Matrix transformationMatrix) : this(new XYZAndLMSConverter(transformationMatrix))
{
}
private VonKriesChromaticAdaptation(XYZAndLMSConverter converter) : this(converter, converter)
{
}
/// <summary>
/// Constructs von Kries chromatic adaptation using given converters
/// </summary>
public VonKriesChromaticAdaptation(IColorConversion<XYZColor, LMSColor> conversionToLMS, IColorConversion<LMSColor, XYZColor> conversionToXYZ)
{
_conversionToLMS = conversionToLMS ?? throw new ArgumentNullException(nameof(conversionToLMS));
_conversionToXYZ = conversionToXYZ ?? throw new ArgumentNullException(nameof(conversionToXYZ));
}
/// <summary>
/// Transforms XYZ color to destination reference white.
/// </summary>
public XYZColor Transform(in XYZColor sourceColor, in XYZColor sourceWhitePoint, in XYZColor targetWhitePoint)
{
if (sourceWhitePoint.Equals(targetWhitePoint))
return sourceColor;
var sourceColorLMS = _conversionToLMS.Convert(sourceColor);
if (sourceWhitePoint != _lastSourceWhitePoint || targetWhitePoint != _lastTargetWhitePoint)
{
var sourceWhitePointLMS = _conversionToLMS.Convert(sourceWhitePoint);
var targetWhitePointLMS = _conversionToLMS.Convert(targetWhitePoint);
_cachedDiagonalMatrix = MatrixFactory.CreateDiagonal(targetWhitePointLMS.L / sourceWhitePointLMS.L, targetWhitePointLMS.M / sourceWhitePointLMS.M, targetWhitePointLMS.S / sourceWhitePointLMS.S);
_lastSourceWhitePoint = sourceWhitePoint;
_lastTargetWhitePoint = targetWhitePoint;
}
var targetColorLMS = new LMSColor(_cachedDiagonalMatrix.MultiplyBy(sourceColorLMS.Vector));
var targetColor = _conversionToXYZ.Convert(targetColorLMS);
return targetColor;
}
}
}
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