On 22/03/2013 22:38, Alfred Molon wrote:

Is there anything better than unsharp mask to sharpen an image? More
specifically, to compensate for a not so sharp lens or a (small)
autofocus error.

If you can characterise the exact point spread function *and* it in
invariant across the field of view then astronomical deconvolution codes
will do a better job but at a cost of some artefacts.

That was how they sorted out the early Hubble images when it was
hopelessly myopic but very precisely made to an incorrect shape.

--
Regards,
Martin Brown