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Author Topic: Deconvolution sharpening revisited  (Read 110384 times)
Lundberg02
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« Reply #340 on: July 12, 2014, 06:42:03 PM »
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I've plowed through the four years' worth of posts here to my benefit, and abstracted many salient points into a doc to keep. I've used Focus Magic for several years with what I thought were very good results, especially in one case where I recovered a license plate from a very motion blurred car. It always bothered me that I couldn't do sub pixel like I always do first in USM, so the suggestion to upsample and the assurance that it doesn't create artifacts was very welcome. I wonder if that's always true, however. In the Photoshop forum, one of the "experts", a man who overkills everything (he has a ten thousand dollar RAID array of SSDs), complained about the chromatic aberration removal tool in CS6 creating artifacts, but only later, after no one else saw them, did he reveal that he always up samples images before doing anything, including printing.

In other news, the fact that a Gaussian PSF is as good as anything else doesn't surprise me, and neither does the fact that a 7x7 array is probably optimal.  I learned long ago (50 years) that a few convolutions of arbitrary transforms closely approximates Gaussian, this is akin to the Central Limit Theorem in probability. Outliers are suppressed by convolution and by adding random variables as well. Sample means from any distribution are Gaussian distributed in the limit, same type of thing.

There is a fairly new app called Blurity for deconvolving that no one mentioned. It's reasonably priced and makes claims of efficacy, but its own examples on the web site show pretty severe ringing, so I didn't bother investigating it. YMMV.

Focus Magic has tutorials that i have only skimmed, but I intend to revisit and follow their forensic tute to gain a better understanding of FM's capability.

As a result of this thread I also bought ALCE from Bigano's website because I was impressed by the examples. It appears to be a sort of super Clarity adjustment, and I hope it will bring to life very old b&w prints from my days in the military. Note that bigano.com has a new website as of this weekend.
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