Abstract: A color video system in which the chrominance portion of a composite video signal, such as an off-air TV signal, is transmitted or recorded in the form of a trisequential sequence containing in lieu of the original colors R, G, B the substitute colors R', G' B', and in which at the receiving or playback end a luminance signal Y.sub.M =0.33(R'+G'+B') is derived from the trisequential substitute color signal, where R', G', B' are chosen so that Y.sub.M also satisfies the relationship Y.sub.M =0.30R + 0.59G + 0.11B required for black and white compatibility. The technique used at the transmitting or recording end obviates the necessity of first developing for this purpose the original colors and then deriving therefrom the substitute colors by the addition to the former of a separate signal Z= -0.03R + 0.26G - 0.22B, as proposed in the prior art.