第18卷第4期 2010年4月
文章编号
1004-924X(2010)04-0973-08
光学精密工程
Optics and Precision Engineering
利用阶跃响应的4f光学系统图像复原
徐鑫，田逢春，姬艳丽，李立（重庆大学通信工程学院，重庆400030）
Vol.18No. 4 Apr.2010
摘要：4F系统的输出图像存在带限低通、随机噪声和相干噪声并存的特点，对其进行复原处理时不仅要注重保护细节，而且还要处理高频随机噪声和低频相干条纹。为了提高其图像质量，针对这些特点提出了一套图像处理方案。首先，利用4厂系统的阶跃响应获取相干噪声的位置和强度的先验信息；然后，对阶跃响应图像和待复原的图像分别进行同样过程和侧重保护图像细节的随机噪声去除，利用4系统的线性特性将两幅去除随机噪声后的图像进行点除以消去相干噪声来完成复原。实验表明，该方案对峰峰信噪比和结构相似度指数都有很好的复原效果，其分别提高了5db和6%左
右；从视觉效果上看，该方法很好地保护了图像细节，符合4系统的要求，关键词：信息光学；图像复原；阶跃响应；轮廉波变换；4了系统
中图分类号：0438.2;TP391.4
文献标识码：A
Imagerestorationof4finformationopticsystemsbystep-response
XU Xin，TIAN Feng-chun,JI Yan-li,LI Li
(CollegeofCommunicationEnginnering，ChongqingUniversity，Chongqing400030,China)
Abstract:The output images from a conventional 4f information optical system are characterized by their limited frequency bands, random noises and coherent noises in coexistence. Therefore, when those images are restored,it is necessary to protect image details better and to remove the noises in high frequency domain and the coherent fringes in low frequency domain. According to these charac teristics, a new method is proposed to restore 4f system images and to improve the image quality. Firstly, the step response image of the 4f system is used to obtain the prior knowledge of the coherent noise, then the step response and pending images are processed to remove the high frequency random noise in contourlet domain. Finally, based on the linear characteristics of 4f system, the pixel value of the pending image divides the pixel value of step response image from point to point to remove the co herent noise. Experiments demanstrate that the method can restore images and protect image details well and its Peak Signal to Noise Ratio(PSNR)and Structural Similarity Index(SSIM) have improved by 5 db and 6%, respectively. These results show that the proposed method is suitable for 4f optical systems.
Key words: information optics; image restoration; step response; contourlet transform; 4f system
收稿日期：2009-06-11；修订日期：2009-09-09.
基金项目：国家自然科学基金资助项目（No.60472037)；中国博士后科学基金资助项目（No.20080430096）