[GEM-dev] Re: meanwhile, in gempixutil...

[IOhannes m zmoelnig]

james tittle wrote:
> hiya,
> 
> ...sorry I've drifted away from multiple_windows for a bit, and back to 
> the color conversion stuff...even weirder is the fact that I'm starting 
> with fromYV12, for gem2pdp...anyway, I'm not really understanding your 
> constants in the yv12 to rgb transforms: it certainly doesn't work in 
> the pdp case (I've made a overloaded function accepting 
> short*'s)...however, the following almost works, but seems to be 
> overflowing or something in the darkest/lightest areas?
> 

yes.

if i understand your question correctly, the colors are not as they 
should be (or rather: most of the colors are fine, but some are clipping)

this is true and known (and bad, btw)

the problem is (i believe), that YUV does not use the whole range from 
0..255 but something like 16..245 (or whatever: i didn't write it down 
and now i cannot find it); i didn't add any clipping for this (which was 
very stupid) because of performance reasons.

oh, bless the lazy, but i really have to find the docs somewhere.

mfg.asd.r
IOhannes