[PD] pix_contrast eats up cpu power

cyrille henry cyrille.henry at la-kitchen.fr
Sat Oct 18 12:59:11 CEST 2008


i don't understand everything on your mail.

with color = color * 0.1 , then every color component (R, G and B) will be 10 times smaller than the original texture color, so the images will be darker.
color value are between 0 and 1, so you can try curve like this : 
 color = pow(color,vec4(0.5));

i don't know exactly what curve to use for a good contrast / saturation, but you can have a look at pix_contrast source code...


olsen a écrit :
> hep cyrille
> thanks for this hint - though it's my first time using shader - i 
> tweaked around a bit with the example. i changed color saturation 
> towards muchocolore in the texture.frag file. although removing color to 
> get a black & white image i'm also loosing opacity f.e. with color = 
> color* 0.1; the image gets almost black.
> where aside the green behind my ears can i find infos about how to 
> handle the shader?
> thanks&salutis
> olsen
> cyrille henry wrote:
>> use shader!
>> you'll have to make your own shader, but adjusting color saturation is 
>> quite easy.
>> see gem documentation/10.glsl/01.simple_texture
>> cyrille
>> olsen a écrit :
>>> hi
>>> roman & me are working on an videoinstallation using gem - only an 
>>> additional [pix_contrast] in the gem chain hits the processing limit 
>>> of our computer - is there a way to adjust color saturation in the 
>>> gpu instead of the cpu in Gem?
>>> thanks&greets
>>> olsen

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