Author Topic: combining images from different scopes and cameras  (Read 721 times)

Offline alcol

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combining images from different scopes and cameras
« on: 2018 January 04 16:34:05 »
Hi folks

Any feedback on the following would be welcome. I have a number of Ha subs taken last year some from an Atik383 camera and some a ASI1600 both on  an ED80 scope (unfortunately the 2 batches rotated by 90 degrees). I recently decided to produce a 4 part mosaic of the Rosette Nebula used the ASI1600 camera on an ED120 scope and wanted to add the data gathered last year.

I read up on how to combine the subs simply using StarAlignment and ImageIntegration.  I have attached the view of the various subs. The 2 images on the left are from the 2 batches subs taken last year with the ED80 scope and the one at top right is a sub of 1 part of the 4 part mosaic taken on the ED120, there are obviously also 3 other sections (not shown). The image, bottom right is the integrated image of all the subs, this is produced using the top right part mosaic sub as the reference image. The other 3 sections of the mosaic would be integrated in the same way.

What I don't quite understand is how to get rid of the various shades of mainly background in the integrated image? It could be cropped out but it would get very close to the nebula in places. Using DBE as the next stage without cropping out the various shades of background would presumably cause some distortions to the image?

Advice on how to progress the mosaic would be appreciated

Offline John_Gill

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Re: combining images from different scopes and cameras
« Reply #1 on: 2018 January 05 07:27:14 »
Hi,

This might help in getting the backgrounds to match.  When doing the StarAlignment, there is an option to enable Frame Adaptation.

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John
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Offline RickS

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Re: combining images from different scopes and cameras
« Reply #2 on: 2018 January 05 09:45:40 »
This might help in getting the backgrounds to match.  When doing the StarAlignment, there is an option to enable Frame Adaptation.

Yes, StarAlignment with frame adaption followed by GradientMergeMosaic often works well for me.

Offline alcol

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Re: combining images from different scopes and cameras
« Reply #3 on: 2018 January 05 19:17:45 »
Thanks Guys, I have checked the settings I used on Staralignment and i didn't have Frame adaption ticked. Will retry with this enabled. Tutorials I have read suggest that this is disabled, but I will give it a try and report back.

Thanks

Offline pfile

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Re: combining images from different scopes and cameras
« Reply #4 on: 2018 January 05 20:44:55 »
there is also a script floating around out there called DNALinearfit (by David Ault) which basically computes the intersection between two panes, then runs LinearFit on the intersection to adapt the frame brightness.

rob

Offline alcol

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Re: combining images from different scopes and cameras
« Reply #5 on: 2018 January 06 10:59:06 »
Hi folks
I haven't explained too well what my problem is.

It is not with the production of the mosaic itself it is about how to combine data sets from different times and different FOV and how to handle the dark areas left on the integrated image (without cropping it out). The images I posted are about the use of subs taken some time ago of the full rosette nebula (two images on the left) and adding this data to an image of one quadrant of the rosette nebula taken recently (the same data would be added to the other 3 quadrants of the nebula).

The problem is what to do about the dark area that result because the old data only contributes to part of the quadrant image - as illustrated by the image bottom right.

As suggested I did re run the star alignment using FrameAdaption but this made no difference.

Thanks for any further help

Offline MikeOates

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Re: combining images from different scopes and cameras
« Reply #6 on: 2018 January 16 10:44:50 »
I you are referring to when you integrate a single panel and you get those different background tones, I have found that if you drizzle, the result blends together much better. If you don't want to make a larger image, just drizzle at 1x

There will be different levels of noise in the image (where there are fewer subs you get more noise), but the tones even out.

Mike

Offline alcol

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Re: combining images from different scopes and cameras
« Reply #7 on: 2018 January 16 11:37:41 »
Thanks Mike, appreciated.