1. A method, comprising: converting pixels within one or more contiguous chunks of pixels of an image to: a first color if a number of pixels within the one or more contiguous chunks of pixels is less than or equal to a first size threshold or greater than or equal to a second size threshold, or a second color if a number of pixels within the one or more contiguous chunks of pixels is between the first and second size thresholds; and determining whether the image comprises spam based, at least in part, on the converting.