Author Topic: IC1396: Stars are too bright. How to bring out the nebulosity?  (Read 3280 times)

Offline k

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Hello All,
I need help to process this image. It has lot of stars and nebula is fainer than the stars.
I'm not able to understand how to bring out the nebulosity and reduce the stars.
If I apply Morphological transform, stars reduce to some extent but not much. If I apply multiple times, it results in weird artifacts.
https://drive.google.com/open?id=0BxEdF2AoMf8NMkhndWdKeUxpdjQ
Please help.

Regards,
Keerthi

Offline Dimitris Platis

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #1 on: 2017 January 08 09:37:11 »
What exactly r u looking for? Something like this?
Unfortunately, the small size creates significant artifacts of color and luminance...but u get the idea.

Offline k

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #2 on: 2017 January 08 12:16:35 »
Hi Dimitris,
Thanks a lot for your reply.
As you can see, there are too many stars in front of the nebula.
Looks like Nebula is buried under the stars.
Is it possible to make the nebula pop up and make stars less bright than the nebula without creating any artifacts?

Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #3 on: 2017 January 08 13:33:30 »
It's all about the star masks. It takes different star masks for the reducing the brightness of the stars and bring out the background.



Mike

Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #4 on: 2017 January 08 14:22:43 »
Thought I would show 2 more images. I have to split the posting because of the attachment size restriction. The first is the core area of this image at full resolution. This is with the brightness reduction.

Mike

Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #5 on: 2017 January 08 14:23:27 »
The second is the same core area but this time without the brightness reduction.

Mike

Offline k

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #6 on: 2017 January 08 21:15:57 »
Hello Mike,
Thanks a lot. This is exactly the result I was looking for.
Can you please share the parameters for the star mask? I could not figure it out from the process container.

Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #7 on: 2017 January 08 23:21:12 »
Here are the mask parameters. They are made from the image in the previous step. So star_mask is made from the image after DBE. star_mask1 from the image after the first MT and so on. The star masks were made from linear images, not stretched. These settings are very image dependent. It is very unlikely these settings would work in other images.

The image12 mask is a 50 percent gray mask made with pixelmath.



Mike

Offline k

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #8 on: 2017 January 09 06:17:30 »
Hi Mike,
Thanks a lot for the parameters. I was able to get similar results with the parameters.
But how did you arrive at mask parameters for the star masks?
TGVDenoise with the parameters given by you dint work properly. It created severe ringing around the stars. So I just omitted this step while processing.
Once again, thanks for your help.

Regards,
Keerthi

Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #9 on: 2017 January 09 14:43:40 »
Keerthi

If you have rings around the stars using TGVDenoise double check the settings and that you are using image12(gray mask) with your image. Here is a link to a posting where I first came across the use of TGVDenoise using the gray mask.
pixinsight.com/forum/index.php?topic=8942


As far as how I get the settings for the star masks, here is a video that I hope makes it a little clearer on how I derive those settings from a linear image. There is no audio and very limited text in the video. I don't have the ability to add voice to it and it's not easy for me to add the text currently. I'm not a video tutorial person, haha.
https://drive.google.com/open?id=0B13r3kYqTf8Nb3VnSVhHOVRabGc

Hope this helps.


Mike

Offline k

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #10 on: 2017 January 11 10:31:44 »
Hello Mike,
Sorry for late reply.
Thanks a lot for the explanation. The star mask tutorial is really nice.
You are the best :)

Regards,
Keerthi

Offline jkmorse

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #11 on: 2017 January 12 07:24:48 »
+1 Mike on the tutorial.  Great content and much needed since for most people star masks, particularly in the linear stage, can be a black box   :-\.

Thanks,

Jim
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Offline msmythers

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Re: IC1396: Stars are too bright. How to bring out the nebulosity?
« Reply #12 on: 2017 January 12 17:39:46 »
Thanks guys.



Mike