Recursive phase estimation for image sharpening

Sharpness maximisation is a method that can be used to correct phase errors in images. In this paper we present a new recursive method to estimate the phase correction required for maximum image sharpness using the square of image pixel intensity metric S2. This method avoids the optimisation step required by other image sharpening approaches. We also present a similar algorithm based on the solution to the sharpness gradient that is applicable to other sharpness measures. The new algorithm is significantly faster than other methods although the rate of convergence is still scene dependent.