1. A method comprising the acts: determining, for each of plural pixels in a received input image, three data, the first datum indicating a value of a first color parameter at said pixel, the second datum indicating a value of a second color parameter at said pixel, and the third datum indicating a value of a luminance parameter at said pixel; generating a histogram for the received input image, said histogram comprising (a) first data indicating a count of pixels in the received input image having said determined first datum within each of M quantized first color parameter value ranges, (b) second data indicating a count of pixels in the received input image having said determined second datum within each of M quantized second color parameter value ranges, and (c) third data indicating a count of pixels in the received input image having said determined third datum within each of N quantized luminance parameter ranges; and comparing the generated histogram against a collection of reference histograms to identify a reference histogram that corresponds to the generated histogram, to thereby identify the input image; wherein at least said act of generating the histogram is performed by a cell phone that includes a programmable device that executes software instructions read from a memory, a camera, a touchscreen and a display; and N is less than half of M.