An extended depth of field is achieved by a computational imaging system
that combines a multifocal imaging subsystem for producing a purposefully
blurred intermediate image with a digital processing subsystem for
producing a recovered image having an extended depth of field. The
multifocal imaging system preferably exhibits spherical aberration as the
dominant feature of the purposeful blur. A central obscuration of the
multifocal imaging subsystem renders point-spread functions of object
points more uniform over a range of object distances. An iterative
digital deconvolution algorithm for converting the intermediate image
into the recovered image contains a metric parameter that speeds
convergence, avoids stagnations, and enhances image quality.