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[OM] Spring Somewhere [was From our yard]

Subject: [OM] Spring Somewhere [was From our yard]
From: usher99@xxxxxxx
Date: Thu, 21 Feb 2013 19:51:41 -0500 (EST)
Dr. D writes

>>No, you've got it.  I know diffraction is frequency related but I 
didn't
>>understand the rest of what you said about sharp cutoffs.  You're now
>>the leader.  :-)

Point-spread deconvolution will not work all that well  to fix blur due 
 diffraction from a small aperture.
Recall form the real Dr. D's link that on FT sensor by F11 max 
resolution is down to about 4MP overall and 3MP
with red light.

http://www.luminous-landscape.com/tutorials/resolution.shtml


Unlike diffraction blur ,Gaussian blur "leaks" enough high frequency 
information into the image that it can be boosted and reconstructed 
(indeed, a gaussian is a very special extremum case that results in max 
blur for the least loss of high frequency detail)

found the below images--not perfect but good enough

original  image:

http://praetoriusphoto.images.s3.amazonaws.com/fmforums/20120322_deconvolution/sinsweep.jpeg

added diffraction:
http://praetoriusphoto.images.s3.amazonaws.com/fmforums/20120322_deconvolution/diffracted_sweep.jpg


note how detail frequencies above the cutoff are almost completely 
wiped out.


Gassian blur added:

http://praetoriusphoto.images.s3.amazonaws.com/fmforums/20120322_deconvolution/gaussian_sweep.jpg

note gradual reduciton of high freq info rather than cut-off.

Dr. Dp   (Diffraction protege)
I trust Dr. D dosen't mind me keeping the training wheels on a while 
longer
-- 
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