Video bit transition advancement circuit

A video display system of the kind in which the brightness of consecutive image points on a screen of a raster scanned CRT is defined by the values of consecutive pels of a digital video drive waveform, each such pel comprising one bit or a plurality of video bits processed in parallel, and in which means is provided for extending the duration of selected pels in the video waveform in order at least partially to compensate for image distortion introduced by the finite video amplifier rise and fall times of the CRT, characterized in that said means for extending the duration comprises, comparator means for examining each pel in relation to its immediately preceding neighbor in order to detect a transition therebetween representing an increase in brightness value from the immediately preceding pel to the currently examined pel, and re-timing means for causing the advancement in time by a predetermined interval of any such transition in the video drive waveform relative to remaining transitions.