Icf Circular Aperture Coded Image Restoration Method

In ICF (inertial confinement fusion) experiments, RAM (ring coded-aperture microscope ) is an important imaging equipment of X-rays, The coded image received through RAM must be decoded in order to estimate the target image, which is the final result of the whole equipment. As for the image restoration methods, there are some disadvantages in traditional Wiener filter method, which the signal-to-noise ratio of spectra has to be replaced with a constant parameter that overlooks the spectral information of the underlying image and noise though the spectra are a priori unknown, and consequently the filtered result may lose some important details and the high quality image restoration can't be obtained.This paper presents a modified Wiener filter for image restoration of RAM images in ICF. In the new method, the traditional Wiener filter is used in the first step of the approach to obtain the initial estimate of the target image, based on which the spectral densities of the target image and noise image are estimated. Then by using the information a new Wiener filter is reconstructed that is used to filter the coded image again to obtain an improved result. The validity of the new method is confirmed by the experiment results given in the paper: for simulations, the mean square errors are decreased more than 10%, and for practical ICF images, the restoration results are improved significantly compared with the results obtained by using the traditional Wiener filters. The approach can also be applied to other image restoration problems such that the point spread functions are known.In addition, this paper presents an approach, by computing relative error, for determining the signal-to-noise ratio parameter in the traditional Wiener filter, which is used in the first step of the modified method. The paper also gives an algorithm for estimating the variance of the imaging noises by computing residual deconvolution errors, which is used in the second step of the modified Wiener filter. These two steps play an important role in the whole approach.The validity of the proposed modified method is confirmed by the simulations and practical ICF image experiment results given in the paper.