1. Apparatus for adaptively thresholding the image pixels that comprise a video image signal on a pixel by pixel basis to distinguish white and black image areas in said video image signal, comprising, in combination: (a) white image signal parameter generating means responsive to transition of the video image signal from black to white to provide a white image signal parameter equal to larger of said video image signal and a preset minimum white signal; (b) black image signal parameter generating means responsive to transition of the video image signal from white to black to provide a black image signal parameter equal to smaller of said video image signal and a preset maximum black signal; (c) first means for combining said white and black image signal parameters to provide an offset parameter for the pixel being processed; (d) second means for combining said offset parameter with the video image signal of at least one neighboring pixel to provide a threshold level for thresholding said pixel being processed; and (e) thresholding means for thresholding said pixel with said threshold level.