If the app uses JS, I recently did a bunch of image processing using the node GM wrapper ('gm' on npm), and it was generally a huge pain in the ass. I found that I couldn't do the edits I needed in a single atomic call to gm, and I couldn't get the wrapper to pipe multiple calls together, so I wound up having to write and manage temp files, and it was all pretty hairy.

I later found a project called 'jimp', which is more or less similar to gm but written in pure JS, and which made it easy to chain calls together into nontrivial edits. Since it has no native dependencies it would probably be easier to bundle with electron as well. Presumably it's slower than gm of course (in my case that didn't matter, so I never looked back).