More filtering foo for Xtina

the_xtina, prompted by a post by hitchhiker, I'm curious as to whether one can write a greasemonkey script that would look at each icon on a page searching for a characteristic file size, image dimensions, and loop time, or some other simple description of the file that wouldn't require actual face recognition-style analysis, and then block either (a) the icon itself, or (b) any post or comment with that icon.

I don't actually care about the specific icon in question and wouldn't use such a script, I'm just curious if this is doable. So don't feel you need to create such a thing, a yes or no would be entirely satisfying to me.