Digital correction circuit and image data processing apparatus equipped with a digital correction circuit

Abstract

In the &ggr; correction circuit, a crossover point arithmetic processing unit performs arithmetic processing for each region on crossover points y in the output data direction of a &ggr; correction crossover line based on a plurality of slope data A respectively specified for each of a plurality of regions and crossover point positions X in the input data direction set in advance. A 5-to-4 encoder and a selector select one of a plurality of slope data A respectively specified for each of a plurality of regions and one result B of the results y of arithmetic processing on said crossover points based on the upper bits of input data, a flag encoder and another selector calculate the difference &Dgr;X from a crossover point position in the input data direction to the input data in the region to which input data belongs, and an arithmetic processing unit multiples the above difference &Dgr;X by the selected slope A, adds the multiplication result to the value of the selected crossover point position B in the output data direction, and outputs that value as a &ggr; correction value. Consequently, even if the number of crossover lines for digital &ggr; correction increases, arithmetic processing is simplified. When an image data processing apparatus is used, a pseudo gray scale processing circuit may be provided in a later stage of this &ggr; correction circuit to decrease the number of data bits.