This repo contains the code required to build Colorblind Goggles, on the iTunes app store.
Link: https://itunes.apple.com/gb/app/colorblind-goggles/id1063875867?mt=8
Image filtering is achieved using OpenGL ES 2.0 shaders, with the .fsh extension.
Sorry this code isn't really cleared up and there may be some unused functions in here.