public void AdjustContrast(float contrast) { float s = contrast + 1.0f; float o = 128 * (1.0f - s); float[] mtx = { s, 0, 0, 0, o, 0, s, 0, 0, o, 0, 0, s, 0, o, 0, 0, 0, s, 0 }; ConcatMatrix(this, mtx); }