IMAGE QUALITY ENHANCEMENT CIRCUIT AND METHOD THEREFOR

According to an image quality enhancing circuit and a method therefor, an impulse for each of an input luminance and color signals is detected. A trimmed mean of a predetermined-sized window is output when the impulse is detected. Otherwise, the input signals are bypassed. Accordingly, noise-reduced luminance and color signals are output. An enhanced luminance signal is output by receiving the noise-reduced luminance signal in a picture unit and independently equalizing histograms for subimages divided on the basis of the mean value of the received luminance signal. A local contrast defined as a difference between the value of an input sample with respect to the enhanced luminance signal and each value obtained by low-pass filtering the samples in a predetermined-sized window including the input sample, and the input sample value is adaptively weighted according to the detected local contrast, so that a changed luminance signal is output. A compensated color signal is output by compensating the noise-reduced color signal according to the changed luminance signal. Thus, impulse noise is effectively removed, and an undistorted color signal is provided while enhancing the contrast of the luminance signal, so that the image quality is greatly improved.