1. A system for processing an image having an image sensor configured to collect image data representing different terrain types comprising: an input configured to receive the image data comprising pixels wherein each pixel has a magnitude; a processor; a memory, wherein the memory has stored therein instructions that, when executed by the processor, causes the processor to: calculate log-magnitudes from the magnitudes of at least a plurality of the pixels; calculate standard deviations of the log-magnitudes for subsets of the plurality of pixels; compute an integral of the standard deviations over a desired range; and an output configured to send threshold data, wherein the threshold data comprises information representing different groups of pixels classified based on a value of the integral relative to one or more integral values.