An Objective Out-of-Focus Blur Measurement

This paper presents a new method for objective measurement of out-of-focus blur images. The essential idea is to derive the point spread function (PSF) of an out-of-focus blur image from the line spread function (LSF). In this method, it is assumed that at least one sharp edge could be detected. Then, the LSF can be constructed from the edge(s). This approach has fast speed as it works in spatial domain without complex Fourier transform or iterative computation. Moreover, a generic criterion for out-of-focus blur measurement is proposed and it can be applied to all images without depending on image contents. The experimental results validate the accuracy and efficiency of the proposed method.