Patent ID: 7956932

Claim:
An image signal processing apparatus comprising: a smoothing module configured to reduce grayscale differences between pixel block units of an input digital image signal, where the grayscale differences are to be detected by using difference information between pixels, and an effect of a smoothing process which rounds the pixels is to be varied according to parameters; a histogram acquisition module configured to acquire a histogram value of the input digital image signal for one frame; a histogram value buffer module configured to buffer histogram values for a plurality of frames, the histogram value from the histogram acquisition module being input to the histogram value buffer module; a luminance level transition detection module configured to detect an interval during which an image gradually changes from light to dark or from dark to light, based on the histogram values for a plurality of frames, and to output a correction parameter during the interval, the correction parameter enhancing an effect of smoothing and reducing the grayscale differences in a plain area; and a correction module configured to provide a parameter to the smoothing module to smooth and reduce the grayscale differences, the parameter being obtained by adding the correction parameter to an initial parameter.