[theora-dev] YUV question

[Holger Waechtler]

<Pine.GSO.4.58.0406040851440.22563 at shell>
Message-ID: <40C565BD.101 at qanu.de>

Mike Melanson wrote:

>> Besides TV standards,
>>nothing holds you fron using something like Y = R/4 + G/2 + B/4, which
>>would considerably speed up codec, or sticking with good old 12-bit RGB.
>
>
> 	True, very true. Which is why the creators of Cinepak did just
> that with their codec over a decade ago...
>
>   http://www.csse.monash.edu.au/~timf/videocodec/cinepak.txt

JPEG2000 defines a similiar colorspace that can get losslessly
transformed from/to RGB using integer arithmethic only, the old
experimental w3d code in the xiph CVS contained something like this too.

The compression of these schemes for color images is not as well as the
one using a model that better matches the human visual sensitivity, but
grayscale pictures get compressed a little better since the U+V
components become true zero due to the symmetric definition of U and V.

Holger