I use this software on my PC to help differentiate between Red and Green on menus in certain programmes. You overlay the Visolve Deflector and capture part of the screen, then apply filters. It literally takes seconds to use. It would be nice if you could just scroll a transparent window over an area to apply the filters live, rather than having to capture an image, but it is the best tool I have found so far. Visit Visolve for more info.