TV Signal Shading Corrector for Input to Digital Image Processor

Abstract

When an ITV camera is used as an input device of a digital image processing system, a conventional shading correction is not good enough for quantitative image processing. Shading correction by software puts a heavy time-consuming burden on a main computer.
In this paper, a TV digitizer with shading correction function controlled by a microprocessor is presented. In the measurement mode, the processor automatically measures the degree of shading and makes up a correction table in RAM area. The gain of a video amplifier is controlled by data read out from the table in DMA mode. In the run mode, digitized data as well as analog signal for monitoring after shading correction are simultaneously obtained.