Hacker News Reader

Not sure I follow - especially if it already depends on IM, how is it different from 'convert -compose difference' or a similar operator?

It looks like it's a thin wrapper around "GraphicsMagick for node". Which itself is a javascript wrapper around GraphicsMagick / ImageMagick.

I'm so glad I didn't go into web development.

ImageMagick is not so cool without a bit of JS.