Author Topic: How to combine one NB color image with one EGB color image?  (Read 165 times)

Offline MineralMike

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I'm imaging the Crescent Nebula with a one-shot color camera -- 23 full-color subs and 14 H-a subs. I want to add the H-a nebulosity to the RGB in the final image. I also want to shrink the stars in this star-rich field to better show the nebulosity.

I have used StarMask and MorphologicalTransformation to shrink the stars. This works well, but many stars have a red perimeter, thanks to the H-a contribution.

I can remove the stars in a 14x H-a image. Is it possible to add the H-a nebulosity to the shrunk-stars RGB image? I think that would achieve the goal of increased nebulosity and stars without red rings.

What's the best way to do this? Should I instead make a star mask from the H-a image, then apply it to the RGB image? After that, I could shrink all the stars to improve the image further.

Thanks for any advice and suggestions.

--- Mike

Offline hvb356

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Re: How to combine one NB color image with one EGB color image?
« Reply #1 on: 2019 July 13 20:29:19 »
Mike,

my proposal in a very short form:

0. Generate a good starmask, take MaskGen.js

1. Apply little convolution to the mask

2. Subtract continuum (R) from Halpha with CS.js

(use the mask)

this will create the emission line image Ie

3. Add the emission line image to the R-channel with PixelMath

$T + Ie * f * ~mask

Start with f = 1, modify, if necessary

4. Continue with AdvSharpening.js, Morph... Etc.

Scripts are available here

http://www.skypixels.at/pixinsight_scripts.html

Regards

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

Offline MineralMike

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Re: How to combine one NB color image with one EGB color image?
« Reply #2 on: 2019 July 13 20:48:15 »
Thanks, Hartmut.

Lots to learn, especially using PixelMath.

--- Mike