Sharpening
 

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.
--

Alfred Molon
------------------------------
Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Sharpening
 

On Fri, 22 Mar 2013 23:38:33 +0100, 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.

Have you tried High Pass sharpening?
http://www.luminous-landscape.com/tu...arpening.shtml
--

Regards,

Eric Stevens

Sharpening
 

In article , Alfred
Molon wrote:

Is there anything better than unsharp mask to sharpen an image?

'better' depends on a lot of things.

More
specifically, to compensate for a not so sharp lens or a (small)
autofocus error.

try photoshop's smart sharpen, with it set to remove lens blur.

Sharpening
 

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

Sharpening
 

In article , Martin Brown says...
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.

Has anybody done this for a not so sharp lens or a slightly defocused
image?
--

Alfred Molon
------------------------------
Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Sharpening
 

On 23/03/2013 08:54, Alfred Molon wrote:
In article , Martin Brown says...
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.

Has anybody done this for a not so sharp lens or a slightly defocused
image?

Pretty much routine these days for certain types of forensics where the
original photograph is important critical evidence and blurred.

A very old example: http://www.maxent.co.uk/example_1.htm
(done in the 1980's)

Computational cost is about 200x normal linear inverse methods so it is
still time consuming even today. But it can be done.

You can get roughly 3x the raw image resolution on a good day with a
trailing wind on the highlights and with sufficient signal to noise. The
catch is that resolution then depends on local signal to noise.

--
Regards,
Martin Brown

Sharpening
 

In article , Eric Stevens
says...
Have you tried High Pass sharpening?
http://www.luminous-landscape.com/tu...arpening.shtml

Just gave it a quick try and it doesn't seem to be better than USM.
--

Alfred Molon
------------------------------
Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Sharpening
 

On 2013-03-23 11:33:44 -0700, Alfred Molon said:

In article , Eric Stevens
says...
Have you tried High Pass sharpening?
http://www.luminous-landscape.com/tu...arpening.shtml

Just gave it a quick try and it doesn't seem to be better than USM.

Using high Pass sharpening can be tricky, and it is very easy to over
do it ending up with an obviously over sharpened image, but done subtly
it can make an image "POP".
How bad is the OoF problem you are trying to fix?

Sometimes applying the USM selectively to the subject only, and
tweaking contrast and levels can differentiate the subject from the
background a little better. Even a bit of localized/selective
tone-mapping can help sometimes. However, for the truly OoF there is
little one can do to save the shot.

NIK have a few tools in Color Efex Pro 4 and NIK Sharpener Pro 2 which
might help.
Color Efex Pro 4 has a "Detail extractor" filter and a "Tonal contrast"
filter which have helped me with some of my problematic shots in the
past, and can be applied selectively.

Sharpener Pro 2 has a RAW "Pre-sharpener" and an output sharpener
neither of which I use, as to my eye the just seem to add too much
noise and don't really do the sharpening job I want.

If you care to post link to the problem file, either RAW or of
reasonable JPEG quality, I am sure that the tinkerers among us will see
if we can come up with a solution.

--
Regards,

Savageduck

Sharpening
 

In article 2013032312113764440-savageduck1@REMOVESPAMmecom, Savageduck
says...
How bad is the OoF problem you are trying to fix?

I was asking a generic question, and was curious to know to what extent
technology has progressed today.

Many cameras nowadays come with inbuilt reduction for vignetting,
chromatic aberrations and geometric distortions.
They might come one day (who knows?) with inbuilt deblurring, allowing
to automatically correct blurriness due to cheap lenses or small AF
errors.
--

Alfred Molon
------------------------------
Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

Sharpening
 

On 2013-03-23 12:40:02 -0700, Alfred Molon said:

In article 2013032312113764440-savageduck1@REMOVESPAMmecom, Savageduck
says...
How bad is the OoF problem you are trying to fix?

I was asking a generic question, and was curious to know to what extent
technology has progressed today.

Many cameras nowadays come with inbuilt reduction for vignetting,
chromatic aberrations and geometric distortions.
They might come one day (who knows?) with inbuilt deblurring, allowing
to automatically correct blurriness due to cheap lenses or small AF
errors.

OK! It was just that you said that you had tried High Pass filter
sharpening and you didn't find it any better than USM. So, I made the
assumption that there was a particular problem which needed fixing, not
a progress report on the digital processing wish list.

The quest for the perfect system continues. ;-)


--
Regards,

Savageduck