"lut" docker

[Boudewijn Rempt]

On Mon, 4 Jun 2012, Boudewijn Rempt wrote:
> On Mon, 4 Jun 2012, Simon Legrand wrote:
>
>> Yeah, two gain and gamma sliders would actually be the 'cherry on top' for 
>> this dockable UI. I'm not
>> sure how viable it is, but it would truly be great to have.
>> But just to confirm this would only be a viewing tool. It would not change 
>> the pixels nor would it
>> change the actual colour profile of the image. It'd be a 3rd step tool 
>> only. 
>>  
>
> Right. The gain slider we actually already have, only it's called exposure in 
> Krita :-). I'm not sure what I can do about the gamma slider, I need to dig 
> in what that does in Nuke and Mari. And since I only have an intel graphics 
> card I cannot run their demos :-)
>

Actually, I think our exposure slider does both exposure and gamma. I'm 
not sure where Adrian got the hardcoded values in the shader from:


uniform sampler2D image;
uniform vec4 exposure;

const vec4 gamma = vec4(0.45, 0.45, 0.45, 1.0);
const vec4 grey = vec4(84.66 / 255.0, 84.66 / 255.0, 84.66 / 255.0, 1.0);

void main(void)
{
    vec4 colour = texture2D(image, gl_TexCoord[0].st);
    colour *= exposure;
    colour = pow(colour, gamma);
    colour *= grey;

    gl_FragColor = colour;
}


Does anyone remember that?

Boudewijn