Morihiko SAKANO, Noriaki SUETAKE^1*, and Eiji UCHINO¹

Division of Natural Science and Symbiosis, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan
¹Academic Domain of Natural Science, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan

(Received December 11, 2006; Accepted June 9, 2007)

The estimation of the point spread function (PSF) is a very important and indispensable task for practical image restoration. Various PSF estimation algorithms have been developed, especially for the out-of-focus blur. However, a majority of them are useless in an extremely noisy environment. This paper describes a new robust PSF estimation algorithm based on a distribution of gradient vectors on the logarithmic amplitude spectrum mapped to the polar plane. The proposed algorithm can estimate the out-of-focus PSF accurately and robustly, even for an image highly corrupted by noise. The effectiveness of the proposed algorithm is verified by applying it to the PSF estimation for out-of-focus blurred and noisy images.

Key words: psf estimation, image restoration, out-of-focus blur, gradient vector, polar plane, comb-like filter

^*E-mail address: suetake@sci.yamaguchi-u.ac.jp