Apply curves node to only a region of a render pass

Hi there, in my last post for the BWC http://blenderartists.org/forum/showthread.php?t=194066 I am wondering if I can apply a curves node to only the region of AO where my character is…any ideas or tuts?
Thanks alot
kub
edit: I think I could solve this using the gimp, but somehow I am not able to open the rendered AO image (jpeg) as a layer…I am using ubuntu 10.04 (system runs since 8.04 and I upgraded a several times). This is maybe a very noob problem as I never was using these two fine programs together in one workflow. I tried with my latest project the “edit externally” function, getting some “could not find file” report. Any help is very appreciated. Will try out to do what I want on Windows Vista and report.

Start reading about render layers. Have you model on its own layer and combine with the rest of the scene after you have applied any curves.
http://wiki.blender.org/index.php/Doc:Manual/Render/Layers

This will certainly lead to the solution, thanks.

Anyone experienced with blender in combination with gimp?

The tip about the render layers was aawesome…as I am learning by doing, sometimes a “kick in the ***” does miracles…

If interested, pls leave a comment in my BWC post. (link above) Any are appreciated.

Cheers,

kub

I believe that you will see, as you get “deeper” into the idea of RenderLayers and the idea of node-based compositing in general, that you have no need to involve Gimp.

@sundialsvc4: Well, for image manipulation there is certainly no need for the gimp (I always remember the film Pulp Fiction…), but for texturing with a design tablet there is a need for gimp I am sure but not quite experienced…I have to learn about the different maps (bump, spec etc.
Diving deeply into Blender makes me stunning every time more as it is a soooooo powerful tool. Somehow a Swiss army knife for CG and every plugin/extension there is for other programs is already integrated. Costs is only the effort you have to make learning it, which is a pleasure with the help of a forum like this…