1. An automatic exposure control circuit, comprising: a hierarchical histogram generator for generating a plurality of histograms of differing resolutions for an image, each histogram comprising a different number of at least one bin, each bin representing a number of pixels in the image having a pixel value within a respective unique range of pixel values for the image, each histogram also corresponding to a unique range of pixel values for the image; and an image exposure adjustment module for adjusting an image exposure setting for the image according to a distribution of pixel values determined from the plurality of histograms.