Picture signal corrector

Abstract

Abstract PURPOSE:To obtain a resolution equal to that of an A/D converting circuit, by performing A/D conversion at an upper limit reference voltage and a lower limit voltage based on a correcting value corresponding to white and black density areas designated on an original picture. CONSTITUTION:A scanning circuit 7 scans a reference white plate ahead the scanning of the original picture, then scans a black density area and obtained white and black reference signals are stored respectively in storage circuits 9, 10. On the other hand, extraction circuits 1, 2 extract respectively white and black data signals of plural picture elements and give them to a mean value circuit 3. The circuit 10 obtains each mean value from the white and black data signals and outputs the white reference signal H and the black reference signal M. A white level tracking circuit 4 and a black level tracing circuit 5 calculate respectively the white reference signal Bb and the black reference signal Bd from the circuits 9, 10 and the upper limit reference voltage VH and the lower limit reference voltage VL from the signal H or M. The A/D conversion circuit 6 takes the volages VH and VL as the upper and the lower limit volage and the A/D conversion is attained with a discriminating level splitting the voltage between them.

Inventors

• 👤 Iwao Tanahashi
• 👤 巌 棚橋

Bibliographic Details