How to use rgb stars in a narrowband image?

[dcastroimage]

Need to remove stars from narrowband image and replace with rgb stars

[jkmorse]

Simplest way would be to do the following steps:

1.  Make a star mask of the NB image covering all the stars you want to replace
2.  Load the RGB image into pixelmath with no other expression, just the file name
3.  apply pixelmath to the NB image protected by the star mask (just pull the little triangle at the bottom left of the tool onto the NB image)

That should do it

[RickS]

I usually add RGB stars to a NB image by extracting the L, a* and b* channels from each then using PixelMath and a star mask to blend the a* and b* from the RGB with the a* and b* from the NB image. Recombine the L, a* and b* for the NB image and voila! Sounds easy but there's always a bit of messing around and tuning for any specific image.  The advantage of this approach is that the original NB star profiles are preserved and only the colour is changed.

Cheers,
Rick.

[jkmorse]

Rick,

I like yours better.  To really get mine to work you pretty much have to kill the NB stars which can result in replacing nice tight stars with bloated ones.

Best,

Jim

[msmythers]

Jim

When making the star mask from the NB image use a structure mask or a smoothness of 0 or 1 in starmask. If it needs a little edge flaring use a very, very minimum amount of convolution. That will usually take care of the bloated stars. You can also use a little erosion in MorphologicalTransformation on your star mask to tighten to reduce the size of the stars in the mask if they are bloated. I like to apply the mask inverted to my working image. Then I tweak the mask with Morph and watch the result in real time in the working image. It's a lot easier to tell when I have the stars covered perfectly.


Mike

 

[Dimitris Platis]

U can really use narrowband stars with excellent results (no magenta) as long as u dot the following.,,,
1) Remove stars by Structure map + Morphological Transformation
2) Create Difference Map
3) Linear fit all filters (Ha, OIII, SII)
4) Add stars to each filter
5) SHO script

[jkmorse]

Mike,

Great suggestions.  I will add them to my workflow.

Best,

Jim

[dcastroimage]

Thanks for all the suggestions guys