Removing/reducing BIG halos in RGB

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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goldspider
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Removing/reducing BIG halos in RGB

Post by goldspider »

I've got some large halos in my M45 data that I'd like to process out (or prevent entirely, but that question is posted on CN).

I've attached a screenshot showing an AutoDev done on my RGB data. The mostly-green halos around some of the brighter stars are very evident. Are there any modules in StarTools that can isolate and reduce them?

Thanks!
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admin
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Re: Removing/reducing BIG halos in RGB

Post by admin »

Hi,

I cannot see the image you attached - would you be able to attach/upload it again?
Thank you!
Ivo Jager
StarTools creator and astronomy enthusiast
goldspider
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Joined: Wed Feb 22, 2017 3:38 pm

Re: Removing/reducing BIG halos in RGB

Post by goldspider »

admin wrote:Hi,

I cannot see the image you attached - would you be able to attach/upload it again?
Thank you!
Let me try this again...
Attachments
halos.jpg
halos.jpg (504.6 KiB) Viewed 5740 times
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Re: Removing/reducing BIG halos in RGB

Post by admin »

These are more than likely secondary reflections.
To fix these in post processing tends to be tricky, but not always impossible... Would you be able to upload the dataset?
Ivo Jager
StarTools creator and astronomy enthusiast
goldspider
Posts: 15
Joined: Wed Feb 22, 2017 3:38 pm

Re: Removing/reducing BIG halos in RGB

Post by goldspider »

admin wrote:These are more than likely secondary reflections.
To fix these in post processing tends to be tricky, but not always impossible... Would you be able to upload the dataset?

Yeah I figured that was what those were; maybe from the filters? I'll be looking into this some more.

I'll upload the data to my Box account and post back with a link to it.
goldspider
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Re: Removing/reducing BIG halos in RGB

Post by goldspider »

Here's a Box link to a folder containing my LRGB stack files.

https://psu.box.com/s/g6oidesl10mdtkckaapdlgzvd4roaz6p
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Re: Removing/reducing BIG halos in RGB

Post by admin »

goldspider wrote:Here's a Box link to a folder containing my LRGB stack files.

https://psu.box.com/s/g6oidesl10mdtkckaapdlgzvd4roaz6p
Thank you for uploading that. It appears the issue is primaily visible in the green channel and not (at all?) in the luminance data. So this may well be an issue with your green filter.
The solution then, is to process this as straight LRGB (or L+Syn L, RGB where the green is not added to the synthetic luminance).

A really quick process with ST 1.6 gives a reasonable result with the green halo barely visible;
NewComposite.jpg
NewComposite.jpg (406.9 KiB) Viewed 5597 times
I'd say this is an encouraging result. Does this help?
Ivo Jager
StarTools creator and astronomy enthusiast
goldspider
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Joined: Wed Feb 22, 2017 3:38 pm

Re: Removing/reducing BIG halos in RGB

Post by goldspider »

Thanks a bunch, I'll give that a shot.

I reached out to Astronomik about the halos, and got a response indicating that it is a characteristic of the filters I'm using. They said that the Type C2 filters have some overlap between color curves for more accurate planetary colors, which can also result in halos like this from brighter stars. They said their "Deep Space" RGB filters don't have any overlap in the color curves, and would almost eliminate these kinds of halos.

Thanks again for the help!
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