Defocus Estimation from a Single Image

This paper derives the formulae for defocus blur parameter from a single image, based upon the line spread function (LSF). To achieve high accuracy and robustness, the over determining strategies are adopted: 1) a number of LSFs on one edge are extracted; 2) more edges in the images are used. The trust-region method is then employed to obtain the optimal estimation of blur parameter. The experimental results have demonstrated the effectiveness of the proposed method. It can be used for blind image quality evaluation in vision-based applications.