1. A method comprising: with at least one electronic device: obtaining one or more electronic signals representing a digital image rendered for display on a display device; identifying at least one test region of said digital image, said test region comprising a first portion associated with a boundary of at least one textual character, and at least a second portion associated with a background adjacent to said at least one textual character, wherein said identifying the at least one test region comprises detecting the boundary based, at least in part, on an edge detection threshold value, including: determining edge values for pairs of adjacent pixels within the digital image; comparing each of the edge values to the edge detection threshold value to identify edge candidate pixel pairs; identifying a plurality of adjacent edge candidate pixel pairs as an edge of the at least one textual character; and specifying one or more of the plurality of adjacent edge candidate pixel pairs as the test region, wherein the first and second portions of the test region comprise respective first and second pixels of the specified one or more edge candidate pixel pairs; generating one or more digital signals representing a test result associated with said test region based, at least in part, on a comparison of at least one image characteristic associated with said test region to one or more test criteria; and initiating display of at least a portion of said test region and at least one corresponding test indicator, said test indicator being based, at least in part, on said test result and comprising one or more electronic signals representing digital image data.