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using System;
namespace Colourful.Implementation.RGB
{
/// <summary>
/// L* companding
/// </summary>
/// <remarks>
/// For more info see:
/// http://www.brucelindbloom.com/index.html?Eqn_RGB_to_XYZ.html
/// http://www.brucelindbloom.com/index.html?Eqn_XYZ_to_RGB.html
/// </remarks>
public sealed class LCompanding : ICompanding
{
private const double Kappa = 24389d / 27d;
private const double Epsilon = 216d / 24389d;
/// <inheritdoc />
public double InverseCompanding(double channel)
{
var V = channel;
var v = V <= 0.08 ? 100.0 * V / Kappa : Math.Pow((V + 0.16) / 1.16, 3.0);
return v;
}
/// <inheritdoc />
public double Companding(double channel)
{
var v = channel;
var V = v <= Epsilon ? v * Kappa / 100.0 : 1.16 * Math.Pow(v, 1.0 / 3.0) - 0.16;
return V;
}
/// <inheritdoc cref="object" />
public override bool Equals(object obj) => obj is LCompanding;
/// <inheritdoc cref="object" />
public override int GetHashCode() => 1;
/// <inheritdoc cref="object" />
public static bool operator ==(LCompanding left, LCompanding right) => Equals(left, right);
/// <inheritdoc cref="object" />
public static bool operator !=(LCompanding left, LCompanding right) => !Equals(left, right);
}
}
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