[vorbis-dev] ogg pic format (again).. here's why
cmh at bDistributed.com
Fri Jan 26 19:29:15 PST 2001
At 6:41 PM +0100 1/26/01, Gerry wrote:
>Both pictures, animations and
>"real" movies (should) have this in common: compress it to as good quality
>and small size as possible. Why not make all in one ?
Except, of course, that they have very different perceptual and
For instance, the Discrete Cosine Transform used in JPEG and MPEG can
result in lots of visual noise in large single-color areas. Most
animation consists of a large number of large single-color areas.
Hence a compression scheme built around a DCT isn't the best for
Similarly, computer images will generally either be in an RGB or CMYK
color space (depending on how they were generated/acquired and where
they're eventually destined to be displayed). Video, on the other
hand, is usually both captured and displayed in a
luminance/chromanance format (often 4:2:2 Y'Cb'Cr'). These three
color spaces have very different gamuts and perceptual behaviors.
(For instance, with color printing -- CMYK, aka "process colors" or
subtractive primaries -- you also have to worry about halftone
patterns and dot gain.)
Chris Hanson <cmh at bDistributed.com>
bDistributed.com: Making Business Distributed
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