// RGB -> YCbCr // Y = Coef. for red*Red+Coef. for green*Green+Coef. for blue*Blue // Cb = (Blue-Y)/(2-2*Coef. for blue) // Cr = (Red-Y)/(2-2*Coef. for red) // YCbCr -> RGB // Red = Cr*(2-2*Coef. for red)+Y // Green = (Y-Coef. for b