Research On All-focus Imaging Method Based On Coded Aperture

This paper focuse on the research of all-focus imaging method based on coded aperture technology, which used the defocus image restoration and coded aperture technology. It can make the blurry regional of image, which caused defocus, get clearer by the algorithm in this paper. The major work done can be summarized as follows:(1) Studied on the relevant theorys of coded aperture, including the origin and appliation of the coded aperture theory, and the potential relationship batween the defocus pattern and the depth of object.(2) Researched the selection method of aperture pattern. First, the blurred image be computed by statistical model, then the similarity between the images at different depths can be computed by this statistics and a very classical algorithm that is Kullback-Leibler (KL) divergence. Finally, used the comparison method proposed in this paper can select the relative optimal pattern.(3) Obtained aperture filters. After aperture pattern was selected, it must extract a group of the filters, which can be got through several steps, including extraction of the defocus images at depths from near to far, interception, segmentation, scaling, normalized and so on.(4) Researched the image restoration method. Through the theoretical analysis, this paper got an equation to solve the clear image from blurry image and the filter. After compare with several solving methods, it was selected, which the method based on the image of sparse distribution. It is the mixed and nested calculation about the iterative re-weighted least squares process (IRLS) and the Conjugate Gradient algorithm.(5) Designed the hardware and software systems. According to the basic need of this research, the appropriate equipment was selected and the design and selection of hardware system were completed. Compiled the various function modules of software system and integrated them. Finally, the hardware and software systems were integrated, and the performance reached to the purpose and requirement of this research.This paper research the all-focus imaging system based on coded aperture, which be used successfully in the restoration work of the blurry image which caused defocus phenomenon. The result shown that this system effectively restoration the defocus image, and the effect of image can basically meet the requirement.