1. A method of computing neighborhoods of pixels which neighborhoods are bounded to include particular image characteristics comprising: (a) using the digital image to compute neighborhoods of pixels which are to be processed and wherein such neighborhoods of pixels are substantially bounded by pixels defining the particular image characteristic; (b) computing an activity number for each pixel based upon the values of adjacent pixels; (c) using the activity numbers for each pixel and activity numbers for adjacent pixels in a predetermined neighborhood to produce a plurality of trend numbers for each pixel related to the particular image characteristic; and (d) using the trend numbers for each pixel to determine the neighborhoods of pixels which bound the particular image characteristic.