[PD] pix_contrast eats up cpu power

[olsen]

cyrille henry wrote:
> hello,
> 
> i don't understand everything on your mail.
i thought adjusting the contrast & brightness needs to be done in the 
frag file - with the update help example its clear!
my problem was by modifing the color argument in the frag file i also 
loose opacity of the whole image instead of contrast only.
as roman mentioned it - now it works exactly the way we need! merci 
mille & two doublescoops of gelato for this move!
olsen
> 
> 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...
> 
> 
> Cyrille
> 
> 
> 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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