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#1
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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 |
#2
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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 |
#3
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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. |
#4
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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 |
#5
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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 |
#6
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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 |
#7
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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 |
#8
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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 |
#9
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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 |
#10
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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 |
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