Aplying gamma to colors

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medzo
Posts: 151
Joined: Fri Nov 13, 2009 2:04 pm

Aplying gamma to colors

Post by medzo »

Hi

Its something i dont understand. In vray all colors are affected by gamma (studio max costumize-preferences-gamma and lut- materials and colors 2,2). What about kray? If i want to simulate vray should all colors be changed to gamma 2,2?
jnom
Posts: 263
Joined: Wed Dec 02, 2009 7:00 am

Re: Aplying gamma to colors

Post by jnom »

Complicated subject. Look for Matts kray lwf tutorial. Basically you enable kray lwf plugin gamma 2.2. Then in kray main gui general tab, set tonemap to linear. Your output should be HRD so you can tonemap in photoshop or ae.
But if you want to burn in the tonemap during rendering, enable kray tonemap blending. Play with the different setting to get different results.
Btw in lightwave you have to disable CS in preference. You might get wierd results if you enable lwf in kray and lwf in lightwave.
medzo
Posts: 151
Joined: Fri Nov 13, 2009 2:04 pm

Re: Aplying gamma to colors

Post by medzo »

i know this is complicated :)

but look, when in vray you set up basic material with color value (diffuse color) like 5 and render you get a dark grey material -not black, in kray to get the same result you need to go to material node and plug color node with value 5 into simple color correction node with gamma value set to 2,2. Even if you have QLW set to 2,2 and tonemap to 2,2. Its like the colors arent affected by tonemaping jut the textures...
jure
Posts: 2142
Joined: Thu Jun 02, 2005 6:53 pm

Re: Aplying gamma to colors

Post by jure »

medzo wrote:Hi

Its something i dont understand. In vray all colors are affected by gamma (studio max costumize-preferences-gamma and lut- materials and colors 2,2). What about kray? If i want to simulate vray should all colors be changed to gamma 2,2?
It is a bit of complicated subject but I'll try to explain it in a simple manner:
The problem originates from the fact that you need to apply gamma correction to your images to properly view them on your monitor.
The proper way to do this is to feed the renderer with LINEAR colors, because rendering calculations happen in LINEAR space. When rendering is done then you need to apply gamma correction to your colors so that they can be displayed properly on your monitor.
Now the easiest way to achieve this is to use Kray QLWF plugin (this will "degamma" INPUT colors) and apply gamma to final rendered image (either via general tab gamma parameter or Tonemap blending plugin).

Note however that in LW10+ you need to set your color space corrections all to Linear for this to work correctly. If you want to use LW10+ CS settings then you shouldn't use Kray QLWF plugin (note however that kray preview rendering is not color corrected so it will look wrong until image is loaded into LW image viewer).

So basicly you control your INPUT and OUTPUT gamma. Both can be controlled in several ways and this is usually where confusion happens.
- Jure
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