非均匀介质退化图像快速仿真模型的建立

Construction of fast simulation model for degraded image by inhomogeneous medium

针对非均匀介质成像仿真速度较慢的问题,提出一种获取近似退化图像的快速仿真模型.按视场将图像分为若干子块,计算得到各子块中心位置的点扩散函数矩阵,建立与像素大小对应的成像退化矩阵.近似认为各子块内成像满足等晕条件,分块卷积快速得到各子块退化图像,并采用少量重叠的方法实现整个视场的无缝拼接,加入畸变信息得到最终的退化图像.建立仿真成像系统,做了多组对比实验,并对光追法得到的精确退化图像和该模型得到的近似退化图像进行相似度的比较.结果表明,在一定相似度的要求下,对于512×512像素的图像实现毫秒级的处理速度.

A fast simulation model for getting approximate degraded images was proposed to raise the low speed of the simulation of images degraded by inhomogeneous medium. The image was divided into several sub-blocks according to the field view. Point spread function matrix of the center in each sub-block was computed to construct the degraded matrix, which was corresponding to the pixel size. Each sub-blocks were approximately regarded as isoplanatic regions and the sub-block degrade images were obtained by convolution calculation. Seamless splicing of the entire field of view images were achieved by the way of a little overlap of the adjacent blocks. The distortion was also added to obtain the final degraded image. With an imaging simulation system built, multiple experiments were done to compare the similarity between the degraded images obtaining by proposed model and ray tracing method. Experiment results show that with the requirement of a certain similarity, the time of simulating an image with the size of 512X 512 is about several milliseconds.