Frame quality test ...
 
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2022-05-29: APP 2.0.0-beta2 has been released !

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Frame quality test based on APP result


 Heno
(@heno)
Red Giant Customer
Joined: 5 years ago
Posts: 114
Topic starter  

I have run a stack of 400 frames through APP. I have manually flipped through every frame and marked the worst ones before stacking. I wanted to see if APP came to the same conclusion as I with respect to frame quality. I have no idea how the various columns are calculated through the processing, but I find the results surprising to say the least.
I have sorted the files on all the relevant result columns and made a copy of what APP claims to be the best and worst frame in that particular sort. Which sort and best/worst frame is included in the file name. While some of these seem reasonable, some do not make any sense to me at all. I can't help asking the question: Are these calculations robust?

Background luminosity worst
Background luminosity best
Dispersion best
Dispersion worst
Quality best
Quality worst
Registration RMS best
Registration RMS worst
SNR best
SNR worst
Star density high
Star density low
Star shape best
Star shape worst
Star shape worst selected

 


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

They usually are yes, but I can imagine that in this case the calculations become a bit hard to make. The quality overall isn't good with the amount of background versus signal and especially when you get close to the background with the signal, it can get tricky. You can always decide to manually throw out data, the quality score is something that's being update during processing based on the info it receives out of each step. Star shape and things are included in there and it can be that some of the frames with a lot of pollution but still very nice stars, could get a higher score.


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 Heno
(@heno)
Red Giant Customer
Joined: 5 years ago
Posts: 114
Topic starter  

I realize that calculating these tings are probably not easy and this test has showed me that I need to change my routines for selecting which frames to stack. Previously I have mostly checked the quality column and if the 2-3 worst frames were acceptable I have assumed that the rest were too. This is obviously not the case. (It probably is if you have "perfect" data.)
I was not initially aware that these frames contained a lot of clouds, but when I started developing the stacked frames I saw that something was not right. Reloading everything to APP and flicking through the files soon revealed why. And that's why I did this test.
I suggested in a post a long time ago that APP should have had a selection criterion facility whereby one could set criteria values for each of the calculated columns and have APP exclude (uncheck) all the frames that would not meet that criterion. Now, more than ever I think this would be very useful.


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Yes, a more fine-tuned selection criterium may be nice to have, as well as flipping though images faster. Mabula is aware of this and wants that to work in later versions. You can, based on quality, always select to integrate 90% for instance, which filters that automatically. Still always a good idea to take out images with clouds and such manually as APP assumes that you load in data that has decent quality, background light pollution and such it can then correct for, but not clouds for instance.


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