Fixing defocus and ...
 
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Fixing defocus and star trails  

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(@ispybadguys)
White Dwarf Customer
Joined: 4 months ago
Posts: 10
June 1, 2021 00:12  

I have only been using APP a week and I am very impressed. Great work. I was able to get going in a few minutes.

 

I am sure you all know how defocus and star trails can get into your collections. I have some collections where PHD2 quit and my collections continued with 2 minute subs. I discovered something that is very useful and might make a good addition to APP. There is an algorithm called Lucy-Richardson deconvolution. I have been trying it in Matlab and it seems to do wonders for both these issues. The algorithm needs an estimated point spread function but a nice bright star gives you this. It takes about 5 minutes to calculate for a 61 mpixel image on a fast MacBook Pro.

I and post some examples.

Kurt


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
June 1, 2021 09:06  

I think Mabula knows about that, he's also interested in deconvolution in a future version of APP. So, we'll need to see if that can be used for some of these examples. In the end though there is only so much software can do and it will probably not be the best for your data, fixing the issues at data gathering is always preferred. I think you can set your capture software to start over when guiding is not ok, I do that to filter a lot (or hopefully just a few) I would throw away anyway later.


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(@mabula-admin)
Universe Admin
Joined: 4 years ago
Posts: 2692
June 1, 2021 14:40  

Dear Kurt @ispybadguys,

Thanks and you are most welcome!

Thank you very much for bringing this to our attention.

Indeed, like Vincent says, we will introduce deconvolution in a future version to solve issues like you mention. It is on our ToDo 😉

Cheers,

Mabula


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(@ispybadguys)
White Dwarf Customer
Joined: 4 months ago
Posts: 10
June 1, 2021 23:44  

Thanks

I used to work at a National Laboratory and we designed and built space telescopes. To get the best possible image out of them we would take several images at different focus positions and we could compute the telescope wavefront error from this and the we used Lucy-Richardson to correct the images. Not only can you correct focus errors but also seeing conditions. Nothing is free you have to trade in some SNR to get this.

 

Kurt


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