> if it's an oft-posted image, a simple diff would show off any hidden messages very quickly. How would that scale though? Many 'oft-posted' images are modifie

> if it's an oft-posted image, a simple diff would show off any hidden messages very quickly. How would that scale though? Many 'oft-posted' images are modified by users for legitimate reasons. You would have to be able to figure out which changes were legitimate and which were hidden messages.