A video signal enhancement unit (100) and an image display apparatus containing the unit have a processing unit (102) for contrast modification of the video signal. The processing unit (102) receives input data from a contrast counter (112), designed to store a contrast count. The contrast count is decreased by a pixel counter (104) each time the total number of pixels which have video signal levels that are higher than a predetermined video level, exceeds a predefined threshold. The contrast count is increased each time a trigger means (114) generates a pulse. A contrast comparator (116) can be coupled to the contrast counter (112) to limit the contrast count to a maximum contrast value.