Author Topic: RGB star color preservation with NB  (Read 229 times)

Offline johnnyK

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RGB star color preservation with NB
« on: 2018 July 08 22:37:46 »
Processing RGB and NB subs together using the script utility NBRGB the stars seem to lose there original colors obtained from the RGB subs. Is there a best practice or tutorial on how to create NB and RGB images while bringing out the star colors.
Converting from PS to PI so I am still new with all the tools available. I was able to generate decent star colors in PS by whiting out ans shrinking the stars in NB subs and overlaying the RGB over the NB with a Lighten Blend mode.
Thanks

Offline akulapanam

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Re: RGB star color preservation with NB
« Reply #1 on: 2018 July 08 23:28:17 »
I was noticing that myself today.  It seems like the HaRVB-AIP script does a better job here

Offline hvb356

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Re: RGB star color preservation with NB
« Reply #2 on: 2018 July 09 08:20:57 »
You may check out my script "EmissionLineIntegration.js", which can be found on Herbert's page:  https://www.skypixels.at/pixinsight_scripts.html
EmissionLineIntegration tries to remove unwanted frequencies from the NB and adds the emission line intensities to the channels. Play with contingents and leave Mue correction unchanged.
This Rosette https://www.flickr.com/photos/hvb_astro/39547057252/sizes/l was made from RGB + Ha + OIII

TOA-150, ML8300, CFW2-7 w. Astronomik HaLRGB, PDF, EM-400, guiding FS-60 + ST402, ASCOM bsd. image acquisition

Offline johnnyK

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Re: RGB star color preservation with NB
« Reply #3 on: 2018 July 09 18:38:52 »
Thanks I will check it out.
JK

Offline akulapanam

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Re: RGB star color preservation with NB
« Reply #4 on: 2018 July 10 19:26:11 »
I played with that script a bit and looked at the PowerPoint here.  http://www.skypixels.at/downloads/PixInsight/Tagung_VIII/EmissionLineIntegration.pdf .  It seems to work fairly well but produces a noiser image and the color tends to be a bit hot pink compared to the RGB frames but maybe better than Salmon?

Offline monkeybird747

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Re: RGB star color preservation with NB
« Reply #5 on: 2018 July 13 13:59:40 »
There is this tutorial that uses a good star mask and MorphologicalTransformation to erode/remove the unwanted stars from the NB image.

http://www.lightvortexastronomy.com/tutorial-reducing-star-sizes.html#Section3

You could try that before combining using one of the above mentioned methods. I'm going to try this on my next processing attempt with some OSC + Ha data. My first attempt shows some of what you are talking about, i.e. some star color loss that is hard to get back. Here is a screen shot of, from left to right, RGB fully processed, Ha integration, RGB+Ha fully processed.