Looks like there is a great new GPUImageLookupFilter.m filter in Brad Larson’s amazing GPUImage library. It uses a CLUT stored as a PNG file to apply color correction to an image. The trick is that you can then optimize your fragment shader to use this image as a texture and look up the destination color in it. This trick seems to be well-known, but not often documented ; I only found one article that described the idea behind CLUTs and how they could be used in an OpenGL shader. I was about to embark on writing all this stuff myself, but it looks like GPUImage made my life easier once more !