Luminance and chrominance are combined along with the timing reference ‘sync’ information using one of the coding standards – NTSC, PAL or SECAM – to make composite video. The process, which is an analogue form of video compression, restricts the bandwidths (image detail) of components. In the composite result colour is literally added to the monochrome (luminance) information using a visually acceptable technique. As our eyes have far more luminance resolving power than for colour, the colour sharpness (bandwidth) of the coded signal is reduced to far below that of the luminance. This provides a good solution for transmission but it becomes difficult, if not impossible, to accurately reverse the process (decode) into pure luminance and chrominance which limits its use in post production.