Could it maybe name the .png files the number of that pixel?
I suppose if there are more than one with the same number (for example, in the SMB3 Mushroom, there are the same number of black and white pixels) you could call one 2A.png and another 2B.png. Or, if there are more than 26 colours, maybe something like 2-001 and 2-002.
I dunno. Just ideas. If the PixelCounter works I won't bother bugging you about it.
I guess you probably want Coinage for that, eh?