Abstract. The spectral method is developed for estimating the parameters of the point-spread function (PSF) in the problem of restorating the distorted (smeared, defocused) im-ages. The method is based on the analysis of a spectrum, or the Fourier transform (FT) of a distorted image. This method makes it possible to estimate the PSF parameters: the angle θ and magnitude Δ of image smearing, as well as the size  of the image defocusing spot. This enhances the image restoration accuracy. The smeared image spectrum is compressed in the smearing direction, and this makes it possible to estimate θ and Δ. The defocused image spectrum is also compressed, and more strongly, the larger the defocusing spot. A new estimates are obtained for the smearing parameters θ and Δ using the Nyquist frequency and for the defocusing parameter  using the Bessel function. The results of applying this method to image processing are presented. The developed technique can be used to enhance the accuracy of smeared and defocused image restoration via their mathematical processing by solving the integral equations.

Keywords: image distortions (smearing, defocusing), point-spread function, distortion parameters, Fourier spectrum of distorted image, Nyquist frequency, Bessel function,

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