Post processing

Hi I want to post process image, and redraw specified color to different color (clearing alpha channel is enough). Exists something like glColorFunc(GL_EQUAL) ?? Is there non shader solution ?
Thanks Filip

[QUOTE=phdr_hroch;1252148]Hi I want to post process image, and redraw specified color to different color (clearing alpha channel is enough). Exists something like glColorFunc(GL_EQUAL) ?? Is there non shader solution ?
[/QUOTE]

If you tried hard enough, you might be able to cook something up using glTexEnv() with multiple textures and passes. But using a shader would be simpler and more efficient.