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Old 25-11-2018, 07:59 AM
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Astrofriend (Lars)
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Lens distortion and correcting

When building mosaics and when doing very wide field photographing it could sometimes be useful to correct the optical distortion.

I try to implement something in the software AstroImageJ were I can do it. There are some plugins but still a bit tricky to get it to work. It's a self learning project/tutorial for myself and maybe others also find it interesting.

Here what I have written down so far:
http://www.astrofriend.eu/astronomy/...istortion.html

It's slowly in progress. The last thing I have done this week is to find the parameters of the optic distortion, page II.

i.e. find a, b and c

r' = a*r + b*r^2 + c*r^3 ...

Correction for rotation symmetric distortion.


There are other software that can do this very easy I think, but I want to do it from the ground to learn more and have more control over it.

/Lars

Last edited by Astrofriend; 25-11-2018 at 08:28 AM.
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Old 25-11-2018, 08:05 AM
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Registar?
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Old 26-11-2018, 06:33 AM
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Hi Bojan,
Thanks for your answere. What I know Registar is only a 16 bit depth software and can I really do align with images that has distortion? Could't find that when reading on he homepage.

Anyway I feel it fun to do my own development. Maybe I later find something better than the AstroImageJ I'm using now. Earlier I used Matlab which is much more powerful in matematics but has problem to handle big size images.

I updatet my homepage with more background information and small corrections.

/Lars
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Old 26-11-2018, 07:56 AM
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Yes, you can align images with distortion.

Central firrst, then surounding frames.

It also takes care of gradient.
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Old 02-12-2018, 08:48 PM
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Hi Bojan,
Thanks for the information.

I have done some more, this time I have took a look how to find the distortion parameters. I used Hugin to do this work.

Here how I did this lens distortion updatet test:
http://www.astrofriend.eu/astronomy/...istortion.html

Still problem how to implement everything in AstroImageJ that my plan was to use. Maybe I at the end have to buy PixInsight, what I see there is a lot of opportunities to do special routines with macros, about the same as I do in AstroImageJ but more astro friendly. But I like open sourch software better.

/Lars
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