Methods, apparatuses, and systems are presented for measuring difference between graphics images relating to performing an arithmetic operation involving a first graphics image comprising a plurality of first pixels and a second graphics image comprising a plurality of second pixels to produce a difference image comprising a plurality of difference pixels, generating measures of proximity from a plurality of ranges of observation within the difference image, wherein the measures of proximity represent spatial proximity of difference pixels to other difference pixels within the difference image, and applying non-uniform weighting to the difference pixels to produce a weighted difference image, wherein the non-uniform weighting depends on the measures of proximity generated from the plurality of ranges of observation.