VIPS's a free image processing system. It aims to be about half way between Excel and Photoshop. It's obviously much smaller than these two, but it's not a toy either (about 200k lines of code). It's very bad at photo retouching, but it's great (much better than programs like Photoshop, I think) at all the other things you use photoshop for. It's particularly good with large images (ie. images larger than the amount of RAM in your machine), and for working with colour. WWW: http://jcupitt.github.io/libvips/