Bitmap bmp = new Bitmap(200, 200);
for (int x = 0; x < 200; x++)
{
for (int y = 0; y < 200; y++)
{
int calc = (int)(((SimplexNoise.Noise.Generate(x, y)+1)/2)*255);
bmp.SetPixel(x, y, Color.FromArgb(calc, calc, calc));
}
}
I was using https://code.google.com/p/simplexnoise/ but you can use any noise generator.
I hope this helps