Sharp-focus image restoration from defocused images

We present a noniterative algorithm for sharp-focus image restoration from multiple defocused images having known relative defocus values between the image planes but unknown absolute defocus values with respect to the in-focus plane. Starting from an arbitrary value of defocus relative to the in-focus plane and using the optical transfer function, the algorithm evaluates the absolute defocus and retrieves the in-focus image of an incoherently illuminated planar object. Experiments with a circular-aperture imaging system confirm the efficiency and robustness of the algorithm. A reconstruction time of approximately 100 ms is attained with two defocused 512x512 pixel images (captured by a 10 bit camera) on a 2.16 GHz laptop.