Circuit for enhancing chrominance transitions in real-time video reception

摘要

A circuit for enhancing chrominance transitions in a received chrominance video signal comprises a linear-phase digital filter supplied with an input stream of discrete chromatic image elements. The filter also has a high-pass transfer characteristic in a region of the frequency spectrum corresponding to an upper limit of a transmitted chrominance signal bandwidth for enhancing high-frequency components of the received chrominance signal. The circuit additionally includes non-linear digital post-processing circuitry which accepts as input an output of the filter and the input stream of discrete chromatic image elements. The non-linear post-processing circuitry acts on the output of the filter to eliminate distortions introduced in the received chrominance signal by the filter. The post-processing circuitry then detects if the received chrominance signal contains a transition pattern corresponding to predetermined patterns. If the chrominance signal matches one of the predetermined patterns, the filter is bypassed and the output of the circuit is equal to the received chrominance signal.