Proposal of an Adaptive HDR System and Electronically Controlled Gamma Correction Circuit for a Surveillance Camera

Abstract

The purpose of this research is to propose a small-scale adaptive HDR (High Dynamic Range) system that can be implemented in cameras that can be applied to simple monitoring systems widely used in small cameras such as webcams, and to develop a gamma correction circuit to be installed in the HDR system to correct image degradation in the camera. Another purpose of this research is to show that image degradation can be largely corrected by controlling the optimal gamma correction value according to the average luminance value of the captured image, and proposed a conversion formula. We also proposed a gamma correction circuit that can electronically control its exponent value, and confirmed the correcting operation as designed by making a prototype circuit. Actually, the gamma correction circuit was used to display a grayscale pattern on an LCD, and the effect of image correction was verified. Future task is correcting image damages of black down and blown out at the same time. And another task is to increase higher cut off frequency of the gamma correction circuit.