4:2:2

A&V

A commonly used term for a component digital video format. The details of the format are specified in the CCIR (ITU-R) 601 standard document. The numerals 4:2:2 denote the approximate ratio of the sampling frequencies of the single luminance channel to the two color (chrominance) channels. For every four luminance samples, there are two samples of each color channel.

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HD

Defines standard definition video signals, where the luminance (Y) is sampled at 13.5 MHz and the color difference samples (R-Y,B-Y) channels are each sampled at 6.75 MHz. This terminology has come into common usage to describe both high definition and standard definition systems where the ratio between luminance and chrominance samples is 2 to 1 (i.e. 2 sets of color difference samples (R-Y,B-Y) for every 4 luminance samples (Y)). Also see 22:11:11