采用MTF定量评估CCD错位成像的成像质量

Quantitative evaluation of image quality of CCD subpixel imaging using MTF

为提高CCD错位成像系统成像质量,提出用MTF方法定量评估CCD错位成像的成像质量,推导了CCD错位成像两种模式的MTF,取人眼能分辨的最低对比度0.05为阈值,分析表明,交错采样和四点采样模式的理论极限分辨率分别提高到1.4倍和1.86倍,奈奎斯特频率处MTF值分别提高了0.110 6(27%)和0.167 9(41%)。用空间频率范围(0,0.5)内MTFA评估CCD成像质量,结果表明,交错采样模式和四点采样模式成像质量均优于CCD普通模式,且四点采样模式比交错采样模式成像质量进一步提高。建立了Matlab仿真CCD错位成像的数学模型,鉴别率板仿真结果验证了应用MTF定量评估CCD错位成像系统成像质量的正确性。

To improve image quality of subpixel imaging further,quantitative evaluation of image quality of subpixel imaging system based on MTF was proposed.The MTF of two main modes of CCD subpixel imaging was derived.Taking minimum contrast ratio of human eye 0.05 as threshold,analysis showed that theoretical limiting resolution of interlaced sampling mode and four-point sampling mode were improved to 1.4 times and 1.86 times respectively,and MTF values at Nyquist frequency of two modes were increased by 0.110 6（27%） and 0.167 9（41%）,respectively.Evaluation of MTFA in（0,0.5） illustrates that two CCD subpixel imaging modes both have better image quality than CCD common imaging mode,and the image quality of four-point mode is the best.A mathematical model for simulating CCD subpixel imaging using Matlab was established,the results of simulation of bar-target verify the correctness of the analysis based on MTF.