一种优化CMOS图像传感器成像质量的方法  

A Method for Optimizing the Imaging Quality of CMOS Image Sensor

作　　者：白琼 杨少华[1] 严明[1] 刘璐[1] 周二瑞 张雪莹 BAI Qiong;YANG Shaohua;YAN Ming;LIU Lu;ZHOU Errui;ZHANG Xueying(Northwest Institute of Nuclear Technology,Xi’an 710024,China)

机构地区：[1]西北核技术研究所,西安710024

出　　处：《现代应用物理》2023年第1期28-33,53,共7页Modern Applied Physics

基　　金：国家自然科学基金资助项目(1177051126)。

摘　　要：噪声及动态范围是衡量CMOS图像传感器成像质量优劣的重要指标,CMOS图像传感器中的噪声主要包括模式噪声及随机噪声。在成像过程中,模式噪声对信号的影响明显大于随机噪声。本文提出了利用线性校正、分段线性校正及多项式拟合校正等多种非均匀性校正方法降低图像的模式噪声;并根据CMOS图像传感器光响应特性曲线,利用二阶多项式拟合方法,将传感器非线性区域的各像素响应校正到接近线性的目标响应曲线上,进一步提升了图像传感器的动态范围及响应线性度。通过实验验证,本文选择的CMOS图像传感器,当图像像元灰度值小于3.6×10^(3)时,采用线性校正方法;灰度值大于3.6×10^(3)时,采用二阶多项式拟合校正方法,对图像在整个曝光区间内的模式噪声的抑制效果最优;此外,经基于多项式拟合方法扩展动态范围后,图像的最大量程可从4.09×10^(3)增至4.79×10^(3)。Noise and dynamic range are important indicators to evaluate the imaging quality of CMOS image sensors.The noise in CMOS image sensor mainly includes pattern noise and random noise.In the imaging process,the influence of pattern noise on the signal is obviously greater than that of random noise.In this paper,linear correction,piecewise linear correction,polynomial fitting correction,and other non-uniformity correction methods are proposed to reduce the pattern noise of the image.According to the optical response characteristic curve of CMOS image sensor,the second order polynomial fitting method is used to correct the response of each pixel in the nonlinear region of the sensor to the near-linear target response curve,which further improves the dynamic range and response linearity of the image sensor.The experimental results show that for the CMOS image sensor involved in this paper,the linear correction method is adopted when the grayscale value of image pixel is less than 3.6×10^(3),and the quadratic polynomial fitting correction method is adopted when the grayscale value is greater than 3.6×10^(3),which has the best suppressing effect on the pattern noise of the image in the entire exposure interval.In addition,after the dynamic range extension based on the polynomial fitting method,the maximum range of the image can be increased from 4.09×10^(3) to 4.79×10^(3).

关 键 词：非均匀性校正 模式噪声 动态扩展 CMOS图像传感器 多项式拟合 

分 类 号：TN911[电子电信—通信与信息系统]