A novel anti-vignetting algorithm for CMOS image sensor

Abstract

In order to eliminate the image vignetting and color aberration caused by the lens, an improved linear approximation algorithm has been proposed in this paper. Firstly a statistical method is adopted to obtain the image central point and the compensation factor curves of RGB three channels which are carried out through the linear extraction. Secondly each RGB channel's attenuation speed is calculated out. Finally the original image is compensated using the obtained attenuation speed. By the software simulation and FPGA verification, the image vignetting can be eliminated effectively and the non-uniform color caused by the lens can be improved significantly. The relative illumination of the image is increased to 97.62 %, and image vignetting phenomenon is disappeared. At the same time, the relative color of the image is increased by 12.8 %, got to 83.14 %. Therefore the image color becomes more uniform. The proposed novel linear approximation algorithm fulfills the requirement of practical applications, and improves image quality effectively. © 2013 Springer-Verlag.