Author Topic: Blotchy result from DBE  (Read 1134 times)

Offline m_abukhalid

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Blotchy result from DBE
« on: 2018 March 05 06:09:57 »
Hello all. I am trying to resolve an issue that I am constantly struggling with to some degree. Attached is a picture Im working on of Leo's triplet (stacked image not sooc) and I've purposefully overstretched it to highlight the purple/brown patches that riddle the photo. I see this right after using DBE process in pixinsight. The ABE process doesnt do as clean or complete a job of removing the gradient but I don't see the same patchy result. Has anyone seen this before? Any idea how to resolve it at the image capture or during background extraction? Any input would be appreciated as I run into this quite regularly. Thanks!

I have uploaded the original XISF file, as well as the ABE and DBE output jpgs here:
Stacked XISF: https://drive.google.com/file/d/1V5QdXEsynAZapfRtjWZVoqE10RrJ82vV/view?usp=sharing
DBE: https://drive.google.com/file/d/1Omcz99wkd2gq5XAY54VbsotCNA6cHwJ_/view?usp=sharing
ABE: https://drive.google.com/file/d/11HBylKbXqtVh4Vs-6rc9GFD6mnFfH1VQ/view?usp=sharing

ps. Stack was generated by using bias and flat frames. No darks were used in calibration for this image as they just made the image worse.

« Last Edit: 2018 March 05 06:29:30 by m_abukhalid »

Offline pfile

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Re: Blotchy result from DBE
« Reply #1 on: 2018 March 05 08:32:19 »
you have samples placed on stars or on the halos of stars... youll need to carefully move them off, using the dark parts of the original DBE as a guide.

Offline catpool

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Re: Blotchy result from DBE
« Reply #2 on: 2018 July 09 07:29:42 »
Did you make the debayering before star alignment?
I had a similar pattern when I made the debayering after star alignment (what a mistake :))

Offline ajniskan

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Re: Blotchy result from DBE
« Reply #3 on: 2018 July 09 11:18:42 »
Hello all. I am trying to resolve an issue that I am constantly struggling with to some degree. Attached is a picture Im working on of Leo's triplet (stacked image not sooc) and I've purposefully overstretched it to highlight the purple/brown patches that riddle the photo. I see this right after using DBE process in pixinsight. The ABE process doesnt do as clean or complete a job of removing the gradient but I don't see the same patchy result. Has anyone seen this before? Any idea how to resolve it at the image capture or during background extraction? Any input would be appreciated as I run into this quite regularly. Thanks!

Did you happen to use local normalization? I sometimes get an image like yours when I have LN in my process flow.

br,
Antti
Imaging with: iOptron CEM25P, TS-Pro 6" RC with Pegasus FocusCube, Altair Astro Hypercam 178C or unmodded Canon 6D. Guiding with SW EvoGuide 50SD, AltairAstro GPcam & PHD2. Control via laptop, huge battery pack & APT/BYE.

Offline GJL

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Re: Blotchy result from DBE
« Reply #4 on: 2018 July 10 01:51:26 »
If you use LocalNormalisation try to increase Scale to 512 or 1024

Gerhard

Offline ajniskan

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Re: Blotchy result from DBE
« Reply #5 on: 2018 July 12 11:39:27 »
If you use LocalNormalisation try to increase Scale to 512 or 1024

Thanks Gerhard, I'll experiment with that. For some reason I've always kept the scale below 256.

Antti
Imaging with: iOptron CEM25P, TS-Pro 6" RC with Pegasus FocusCube, Altair Astro Hypercam 178C or unmodded Canon 6D. Guiding with SW EvoGuide 50SD, AltairAstro GPcam & PHD2. Control via laptop, huge battery pack & APT/BYE.