1. A cell phone comprising: a processor; a memory; a camera system; and a wireless interface; the memory storing instructions causing the processor to perform the following operations: obtain a frame of image data from the camera system; generate multi-dimensional histogram data from the obtained frame of image data, the histogram data having plural dimensions and defining a greater plurality of histogram bins, first and second dimensions of the plural dimensions corresponding to quantized hue information, a third dimension corresponding to quantized illumination information processed with a second derivative function; compare the generated histogram data with plural sets of reference histogram data; and by reference to the comparison, identify one or more candidate matching images corresponding to the captured image.