IMAGE DETAIL IMPROVEMENT IN A VERTICAL DETAIL ENHANCEMENT SYSTEM

摘要

In a color television receiver including a comb filter for separating luminance and chrominance components of a color television signal, a network is included for enhancing vertical image detail to enhance vertical resolution in the luminance content of a displayed image. The comb filter provides a combed luminance signal output from which vertical detail signal information has been unavoidably deleted, and a combed chrominance signal output including signal frequency components representative of the deleted detail signal, which are selectively extracted from the combed chrominance signal. Low level detail signals are restored to the combed luminance signal via a first signal processing network which exhibits a prescribed signal restoration gain. The detail signal is also added to the combed luminance signal via a second network which cores (removes) low level detail signals including noise in a first operating mode, and amplifies higher level detail signals to enhance vertical image definition in a second mode. Rapid transitions from the coring to the enhancement mode are undesirably manifested in a displayed diagonal image as serrations along the edge of the diagonal line. The visible effects of the serrations are reduced to an acceptable minimum by low pass filtering the enhanced cored detail signal before being added to the combed luminance signal.