1. A method of processing image data to aid in discerning patterns therein, the method being performed by a hardware image processing device and including the acts: (a) defining a block of N rows and N columns of pixel data, from a larger set of image data, where N is at least five, the block thereby comprising at least 25 pixel locations; (b) identifying plural gradient values from said block, each of said values comprising a difference between a pixel value at a center location of the block, and a pixel value at another location in said block; (c) combining the identified gradient values for the block, and using the resulting combined value to establish the value of a pixel in an output image, at a position corresponding to said center pixel; and (d) repeating acts (b) and (c) for other N×N blocks of pixel data in said larger set, to thereby yield an output image from which certain patterns may more easily be discerned.