1. Apparatus for optically inspecting a graphic pattern on a product for identity with the graphic pattern on a previously-examined training sample, comprising: a video camera, means for positioning a product to be inspected so that said camera scans a rectangular frame portion containing graphic patterns of said product, window gate means operative to define a plurality of electronic window areas within the scanned frame, and to pass the video signal from the camera solely during scans through said window areas, means to manually preset the sizes and locations of said windows so that they closely surround the training graphic pattern, means operative during an inspection of a product to automatically enlarge said windows enough to be sure that said graphic patterns are included therein, and then contract said windows until they closely surround said graphic pattern, said means to enlarge each of said windows including means to compute a plurality of vertically-enlarged overlapping search windows and a plurality of horizontally-enlarged overlapping search windows, video signal processing means operative to translate the video signal passed by said window gate means into representative feature sets of digital signals, and means to compare said feature sets of digital signals with feature sets of digital signals obtained during a previous examination of the corresponding rectangular frame portion of the training sample.