Notpron Forums

I'm stuck on this level for about 2 months now.
I think i know what i'm supposed to do, but i don't really know what i'm looking for. I noticed something suspicious, but no matter how much i play around in GIMP or Paint Shop, i can't make it visible.
Any hints? Please?
I hate squares.

It's pretty easy if you use Gimp or Photoshop, but also very boring and lengthy.

I got all 3 differences, but one of them won't work.
I only get the "be more specific" hint. But it doesn't matter how much "specific" my answer is, it's always wrong.