[SDL] YUV ( What is this? )

[Tim Angus]

Miguel Pragier wrote:
> Could anyone please explain me, in a few words, what is YUV?

YUV is a colour space format. A colour space has a number of planes that 
define the colours. The most obvious colour space is RGB, whereby the 
luminance (brightness) of the red, green and blue colour components are 
stored separately in each plane.

YUV is different in that there is only one luminance plane (Y) and two 
chrominance planes (U, V) that indicate the colour. Additionally, the 
chrominance planes are normally subsampled relative to the Y plane, as 
the human vision system is not as sensitive to chrominance differences 
as it is with luminance. This subsample is normally a quarter of the 
luminance plane, i.e. 1 "sample" on the chrominance plane represents 4 
pixels of colour info in the final image. Relative to an RGB image 
therefore, a YUV image usually uses half the storage requirements.