Extraction of the focused object in an image by filtering out the defocused background

Considers the problem of extracting the focused object in an image with defocused background. Such background blur is caused by the defocusing effect of the camera lens. These types of image appear quite often, such as in racing, imaging a person in a scene, imaging a close object of interest, etc... The authors propose to extract the focused object by filtering out the defocused background in those images. A filter is designed based on the optical property of the defocusing process. Such a filter together with some postprocessing techniques are applied to extract the focused objects in images with defocused background. Experiments show that the method is quite effective in doing the desired task