absolute point of focus processing technique

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TheSkyBurner
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absolute point of focus processing technique

Post by TheSkyBurner » Fri Jun 08, 2018 6:15 pm

http://www.cedic.at/apfr/

Has anyone tried this method of image processing yet? It seems slightly different from iterative smart sharpening.

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PDB
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Re: absolute point of focus processing technique

Post by PDB » Sat Jun 09, 2018 6:54 am

Yes I tried, but had to find out the alternatives in Gimp first (not same commands). It is a lot of work and it works. But if it is really so much better than other sharpening techniques? Probably, but I did not get bettter results (but thats probably me, giving up too fast)

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Bruce Girrell
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Re: absolute point of focus processing technique

Post by Bruce Girrell » Sat Jun 09, 2018 6:00 pm

At the end of the intro video, Kaltseis suggests that we read the "additional information" PDF file before viewing the next video (at 4:15 in the video). I can't seem to locate the PDF file. Anyone else know where it is? Is it maybe the information on the main page with the red label "usage" that then starts off "additional APF-R informations"?

I also have to ask a newbie question. The instructions state "if your system provide a pixel scale by 0,8" (arcsec) and your seeing is 2" (arcsec) ..."
How do I determine those values?

Thanks

Bruce G

Edit: After viewing video #2, I think that the "additional APF-R informations" that I referred to above is the part that he wants you to read.
Last edited by Bruce Girrell on Sat Jun 09, 2018 7:00 pm, edited 1 time in total.

Bruce Girrell
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Re: absolute point of focus processing technique

Post by Bruce Girrell » Sat Jun 09, 2018 7:03 pm

OK... I'm going to have to view that a couple of times. I'm good up to the conversion to smart objects and then I start to lose it. Apparently it is this part that is represented by the R of APF-R. The technique up to that point is essentially a multi-resolution unsharp mask.

It is clearly an effective method. I would be reluctant to attach the word "focus" to it though, as it is not a physics-based process (such as deconvolution). Kaltseis notes that if you do deconvolution, it should be done first and should be gentle. The APF-R method is very effective at achieving local contrast enhancement and to our brains, contrast is almost the same as sharpness.

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PDB
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Re: absolute point of focus processing technique

Post by PDB » Sat Jun 09, 2018 7:03 pm

Hi Bruce,

Pixel Scale in " can be calculated as follows (if I remember correctly):

2*ArcTan("PixelSize in Micrometer"/ 1000/2/"Focal Length in mm")*206265

Seeing Value: that is difficult. You have an average seeing for your location (meteoblue gives some indication) but in lucky imaging you probably need an average value reported from an Solar Seeing Scintillation monitor (commercially available or DIY viewtopic.php?f=9&t=16746)

P

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_Zakalwe
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Re: absolute point of focus processing technique

Post by _Zakalwe » Sun Jun 10, 2018 12:45 pm

Its not a focus technique, but a post-processing sharpening routine.

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