One of the ratios of sampling frequencies used to digitise the luminance and colour difference components (Y, B-Y, R-Y) or the RGB components of a video signal. In this ratio there is always an equal number of samples of all components. RGB 4:4:4 is commonly used in standard computer platform-based equipment and when sampling film. While it may appear to offer the potential of yet better pictures formed from more data, television recording and transmission systems are based on 4:2:2, 4:1:1, and 4:2:0 Y, B-Y, R-Y sampling so, in most cases, the gains are limited and can be negated by the conversions between the sampling systems. However, film is commonly scanned at 2k and recorded directly to disks. The signal is then kept in the RGB form all the way through the Digital Intermediate process to the film recorder.

See also: 2k (Digital Film Supplement), Digital intermediate (Digital Film Supplement), Dual link