ImageSharp/tests/ImageSharp.Tests/TestDataIcc/Conversion/IccConversionDataLutEntry.cs

// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using System.Numerics;
using SixLabors.ImageSharp.Metadata.Profiles.Icc;

namespace SixLabors.ImageSharp.Tests.TestDataIcc.Conversion;

public class IccConversionDataLutEntry
{
    private static readonly IccLut Lut256 = CreateLut(256);
    private static readonly IccLut Lut32 = CreateLut(32);
    private static readonly IccLut LutIdentity = CreateIdentityLut(0, 1);

    // test cases were originally calculated unaware that
    // IccConversionDataMatrix.Matrix3x3Random is actually the row-major transposed matrix
    // of the typical column-major matrix
    public static float[,] TestMatrix =
    {
        { 0.1f, 0.4f, 0.7f },
        { 0.2f, 0.5f, 0.8f },
        { 0.3f, 0.6f, 0.9f }
    };

    private static readonly IccLut8TagDataEntry Lut8 = new(
        [Lut256, Lut256],
        IccConversionDataClut.Clut2x1,
        [Lut256]);

    private static readonly IccLut16TagDataEntry Lut16 = new(
        [Lut32, Lut32],
        IccConversionDataClut.Clut2x1,
        [LutIdentity]);

    private static readonly IccLut8TagDataEntry Lut8Matrix = new(
        TestMatrix,
        [Lut256, Lut256, Lut256],
        IccConversionDataClut.Clut3x1,
        [Lut256]);

    private static readonly IccLut16TagDataEntry Lut16Matrix = new(
        TestMatrix,
        [Lut32, Lut32, Lut32],
        IccConversionDataClut.Clut3x1,
        [LutIdentity]);

    private static IccLut CreateLut(int length)
    {
        float[] values = new float[length];
        for (int i = 0; i < values.Length; i++)
        {
            values[i] = 0.1f + (i / (float)length);
        }

        return new IccLut(values);
    }

    private static IccLut CreateIdentityLut(float min, float max) => new([min, max]);

    public static object[][] Lut8ConversionTestData =
    [
        [Lut8, new Vector4(0.2f, 0.3f, 0, 0), new Vector4(0.4578933760499877f, 0, 0, 0)],
        [Lut8Matrix, new Vector4(0.21f, 0.31f, 0.41f, 0), new Vector4(0.40099657491875312f, 0, 0, 0)]
    ];

    public static object[][] Lut16ConversionTestData =
    [
        [Lut16, new Vector4(0.2f, 0.3f, 0, 0), new Vector4(0.3543750030529918f, 0, 0, 0)],
        [Lut16Matrix, new Vector4(0.21f, 0.31f, 0.41f, 0), new Vector4(0.29739562389689594f, 0, 0, 0)]
    ];
}