Author Topic: Techniques for blending RGB stars into narrowband images  (Read 8039 times)

Offline marekc

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Re: Techniques for blending RGB stars into narrowband images
« Reply #15 on: 2013 October 13 13:32:27 »
Hi Rick,

I think your efforts paid off. Those look like good RGB stars to me. I haven't shot narrowband yet, but when the time comes for me to tangle with putting RGB stars into an NB image, I'd be happy to get a result like yours.

- Marek

Offline RickS

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Re: Techniques for blending RGB stars into narrowband images
« Reply #16 on: 2013 October 13 14:33:33 »
Thanks, Marek.

Offline sixburg

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Re: Techniques for blending RGB stars into narrowband images
« Reply #17 on: 2014 January 29 16:51:09 »
How is this step performed:  "...and then used PixelMath to assign the values from the RGB image to the NB image"?

Thanks. 

Offline RickS

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Re: Techniques for blending RGB stars into narrowband images
« Reply #18 on: 2014 January 29 18:59:56 »
How is this step performed:  "...and then used PixelMath to assign the values from the RGB image to the NB image"?

I applied a star mask to the NB image and then applied a PixelMath expression which was just the name of the RGB image to it.  That copies the RGB image over the NB image where it is not protected by the mask.

I have since found a better way which I described in my processing notes here: http://pixinsight.com/forum/index.php?topic=6486.msg44134

The relevant steps are:
- Create star mask from NB luminance * strong HDRMT
- Extract CIE L*a*b*
- PixelMath a*: iif(RGB_star_mask>0.1,RGB_star_mask*CIEa(RGB_stars)+(1-RGB_star_mask)*$T,$T)
- PixelMath b*: iif(RGB_star_mask>0.1,RGB_star_mask*CIEb(RGB_stars)+(1-RGB_star_mask)*$T,$T)
- Repeat a couple of times
- Recombine L*a*b*

Cheers,
Rick.

Offline mads0100

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Re: Techniques for blending RGB stars into narrowband images
« Reply #19 on: 2014 February 02 01:53:41 »
There is a windows program called Straton that will remove your Narrowband stars.