public class PaletteColormap : ScottPlot.Drawing.IColormap
{
    public string Name => "SpecialColormap";

    private readonly byte[] RedValues = new byte[256];
    private readonly byte[] GreenValues = new byte[256];
    private readonly byte[] BlueValues = new byte[256];

    public PaletteColormap(Color[] colors)
    {
        for (int i = 0; i < RedValues.Length; i++)
        {
            int colorIndex = colors.Length * i / RedValues.Length;
            RedValues[i] = colors[colorIndex].R;
            GreenValues[i] = colors[colorIndex].G;
            BlueValues[i] = colors[colorIndex].B;
        }
    }

    public (byte r, byte g, byte b) GetRGB(byte value)
    {
        return (RedValues[value], GreenValues[value], BlueValues[value]);
    }
}