1. A method for all-in-focus image reconstruction and depth map generation in an imaging device, the method comprising: capturing a multi-focus image by the imaging device; partitioning the multi-focus image into a plurality of blocks; determining, for each block of the plurality of blocks, a best inverse multi-focus point spread function (PSF) for reconstructing original image intensity values in the block, wherein the best inverse multi-focus PSF is selected from a plurality of predetermined inverse multi-focus PSFs stored in a memory of the imaging device; and applying to each block of the plurality of blocks the best inverse multi-focus PSF determined for the block to reconstruct the all-in-focus image.