Abstract: Motion blur is caused by the relative motion between object and imaging system,and precise motion blur parameters are needed when the uniform linear motion-blurred image is recovered.It can be proved that the motion blur parameters are relative to the zero points of Fourier spectrum.The number of dark lines is related to the fuzzy scale,and the spectrum dark lines are perpendicular to the angle.In the detection of the dark lines of spectrum,due to the image structure or noise,it is difficult to accurately locate the spectral dark lines,and the spectral structure will be affected by image’s aspect ratio.To deal with these problems,this paper proposed a way named bottom-hat which are used in morphology and processed it in the blur image spectrum,and then used the Hough transform to find the blurred angles.Blurred angles and the distance between two mid zero points were used to find the blurred length.Experimental results show that the errors of blurred length detected by the proposed method are lower than 0.25 pixels,and the errors of the angle are lower than 0.6°.The proposed method is very robust for it can estimate the blur parameters of blurred images in different scales and contents.

Key words: Blur angle, Blur length, Bottom-hat transform, Fourier spectrum, Hough transform, Motion blur