Automatic brightness contrast lighting circuits and luminance/color difference signal processor and video display apparatus comprising the same

摘要

The object of the present invention is to easily compensate automatic brightness limiting performance and automatic contrast limiting performance even if a picture is displayed with a different aspect ratio and to prevent deterioration of picture quality such as graduation and sharpness. A picture display apparatus includes (1) an ABL (automatic brightness limiter) circuit including a comparison circuit for varying an EHT compensation starting point, an ABL gain control circuit for varying a slope of EHT regulation characteristic against APL, an ABL comparison voltage generator, a DAC for adjusting an ABL compensation starting point and a DAC for adjusting an ABL gain and (2) an ACL (automatic contrast limiter) circuit including another comparison circuit for varying an EHT compensation starting point, an ACL gain control circuit for varying a slope of EHT regulation characteristic against APL, an ACL comparison voltage generator, a DAC for adjusting an ACL compensation starting point and a DAC for adjusting an ACL gain. MATH