Human retinal receptors respond to light energy in terms of its red, green, and blue light components, so RGB light control works best for imaging display devices. The native video signals produced by computers and game consoles are typically uncompressed RGB signal format, however, since their transmission mediums do not benefit from signal compression. RF tuners, cable and satellite set top boxes, and DVD/Blu-ray disk players all natively transmit or store YCbCr format digital video signals, since each of these limited bandwidth transmission and storage mediums benefit from signal compression. YCbCr video is considered a form of lossless compression, as the elements of the original RGB signal that are removed in creating YCbCr are picture elements that humans aren’t able to see at normal viewing distances. During creation of YCbCr signals from RGB (the encoding process), higher frequency signal content is removed from the Cb and Cr channels to compress the signal. The two chroma channels, Cb and Cr, are color difference channels. The luma channel, typically denoted Y (more accurately Y’, indicating that the channel is gamma encoded), approximates the monochrome picture content.

In YCbCr, Y is luma (brightness), Cb is blue minus luma (B-Y) and Cr is red minus luma (R-Y). The difference between YCbCr and RGB is that RGB represents colors as combinations of red, green and blue signals, while YCbCr represents colors as combinations of a brightness signal and two chroma signals.

This conversion of the processed YCbCr component video signal into an RGB signal is done by the display’s color decoder. electron gun and phosphors in a CRT, imaging chip(s) and filters in an LCD). However, at the end of a display’s video processing path, the YCbCr component video signal needs to be converted back to an RGB signal, to be usable by the display’s imaging control device (e.g. Modern video displays with HDMI digital inputs process video signals in YCbCr format.

A video display color decoder converts a YCbCr digital video signal back into its original RGB format.

Light blue color code for processing