recoloring noise

Introduction

• 2D noise is often represented as a grayscale image.
• It is often useful to recolor this image so it can be used as a texture.

Code

public static unsafe Mat RecolorNoise(Mat mat, Color lowColor, Color highColor)
{
    if (mat.NumberOfChannels != 1 || mat.Depth != DepthType.Cv8U)
    {
        throw new Exception("Input mat must be grayscale");
    }

    Mat gradient = CreateLinearGradient(256, lowColor, highColor);

    byte* buffer = (byte*)mat.DataPointer.ToPointer();
    byte* end = buffer + mat.Width * mat.Height;

    byte* kGradient = (byte*)gradient.DataPointer.ToPointer();

    Mat recolored = new Mat(mat.Width, mat.Height, DepthType.Cv8U, 3);
    byte* kRecolored = (byte*)recolored.DataPointer.ToPointer();

    while (buffer != end)
    {
        int gradientOffset = *buffer * 3;
        *kRecolored++ = kGradient[gradientOffset];
        *kRecolored++ = kGradient[gradientOffset + 1];
        *kRecolored++ = kGradient[gradientOffset + 2];
        buffer++;
    }

    return recolored;
}

Usage

static void Main(string[] args)
{
    Mat noise = GetFractalOpenSimplexNoise(500, 500, 1 / 128f, 3, 0.5f);

    Mat sky = RecolorNoise(noise, Color.FromArgb(67, 150, 228), Color.White);
    CvInvoke.Imshow("test", sky);
    CvInvoke.WaitKey(0);
}

Output