A Reduction Method of Photon Shot Noise on CMOS Image Sensor Based on Local Brightness Distribution

Abstract

The noise is contained with the photographic image when taking a picture by CCD Image Sensor and CMOS Image Sensor. The typical noise is divided into two elements. Former is a random noise and latter is a fixed pattern noise. The random noise is generated by the variance of the sensitivity of the photodiode and the threshold of the transistor. However, it is decreased by the semiconductor processing technology and the noise reduction technology. In the development of CMOS image sensor, the random noise will become a problem. In this study, the focus is on the photon shot noise. When taking a picture in the environment of a low luminance, the photon shot noise becomes especially predominant. I proposed a method which used a smoothing filter, a median filter and the edge reinforcement with an index from luminance variance in local area of image. A proposed method and a conventional method are used and two dimensional filters were processed. PSNR (Peak Signal Noise Ratio) is used for the comparison and the evaluation. As a conclusion, it is confirmed that the proposed method can decrease the noise more to extent compared with conventional method.