[jugglemaster] Juggling Videos

Paul Norton luap at icculus.org
Wed Aug 25 05:27:59 EDT 2004

off on a tangent! CYM/CYMK is a printing thing, being more appropriate as 
dyes absorb light, whereas monitors create it (i.e. CYM mixes absorptions 
to create a colour, and RGB mixes light)

YCrCb is an alternative way of representing RGB, and seems fairly common 
in the video area. Y is the luminance, Cr is the red-chrominance, and Cb 
is the blue chrominance. The technique takes advantage of the fact that 
the human eye is more sensitive to luminance than chrominance, so you can 
bin some of the chrominance information without much perceived loss of 

This is usually demonstrated by reducing the number of bits of the 
chrominance channels.

video takes advantage of it by storing less samples of Cr and Cb than Y.
has a better description than I could give of what's going on with the 
video stuff.

Surely there must be existing GPL code for converting an RGB frame to 
YUV/YCrCb ?! (or vice-versa)


On Tue, 24 Aug 2004, Perry Rivera wrote:

> Gary,
> Well I do know that monitors tend to be RGB, and printouts CYMK or various
> additions to the CYMK theme.  The K is needed because the CYM makes a really
> dark color but not a true shade of black.
> My 2 pesetas,
> -Perry ...
> -----Original Message-----
> From: Chunky Kibbles [mailto:chunky at icculus.org]
> Sent: Tuesday, August 24, 2004 19:10
> To: jugglemaster at icculus.org
> Subject: [jugglemaster] Juggling Videos
> http://icculus.org/jugglemaster/mpeg/
> Somewhat less hacky and ugly than the postscript "printouts".
> Unfortunately, I don't understand colorspace conversion from RGB to
> YCrCb. If anyone out there wants to lend a hand, I'd really 'preciate
> it :-)
> Gary (-;

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