Techniques for blending RGB stars into narrowband images

[marekc]

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

[RickS]

Thanks, Marek.

[sixburg]

How is this step performed:  "...and then used PixelMath to assign the values from the RGB image to the NB image"?

Thanks. 

[RickS]

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.

[mads0100]

There is a windows program called Straton that will remove your Narrowband stars.