Adaptive contrast and brightness enhancement with color preservation

摘要

A method and apparatus for selectively enhancing contrast depending on the level of incoming video signals while preserving colors are provided. An apparatus for enhancing the contrast and brightness of a video signal displayed on a display device includes: a first luminance level transformation circuit that receives luminance and chrominance signals, reduces the level of the luminance signal in response to a first control signal, and outputs the chrominance signals and the luminance signal whose level has been reduced; an image converting circuit that receives the output signals from the first luminance level transformation circuit and converts the received signals into RGB video signals; and a second luminance level transformation circuit that receives the RGB video signals from the image converting circuit, concurrently increases the respective levels of the RGB video signals in response to a second control signal, and outputs the RGB video signals whose levels have been increased. It is desirable that the display device is a color display tube ("CDT"), a thin film transistor liquid crystal display ("TFT-LCD"), or a plasma display panel ("PDP").