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Soft, dull stars in processing

Russell Croman Astrophotography StarXTerminator Pleiades Astrophoto PixInsight Processing Deep Sky
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Evan Boyle avatar
Evan Boyle avatar
Hello everyone!

I have a quick question about processing stars in Pixinsight.

If you have a look at my more recent images I've posted on Astrobin, a lot of my stars appear soft and doughy and also lack vibrant colours.

I'm getting to a point where I'm relatively happy with my processing workflow for nebulae, but the stars themselves still seem to be tricky. I'm curious if this is purely due to my acquisition methods and the stars are a bit out of focus so there's only so much that can be done in post processing, or if there's something I'm not doing properly in Pixinsight?
I really would like nice sharp pinpoints of vibrant colours in my image, but instead I'm always left with slightly oddly coloured doughy blobs! 

I always run a StarXTerminator and process the stars and nebulae seperately, though I don't really know what I'm doing when it comes to processing the stars on their own if truth be told. 

Any insight or advice would be greatly appreciated!

Kind regards and clear skies!
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andrea tasselli avatar
andrea tasselli avatar
Star size and shape look alright to me, for what I have seen in RGB. Colors are a bit lacking for sure, across the board. To that Arcsinhstretch is the answer plus HT.
Dcolam avatar
Dcolam avatar
Hi Evan,

I think, you are self critizing on a high level here smile

The stars look nice. But I know what you mean, I also had this thought in the past with my pics and I just accepted the stars how they are. Seeing your pictures, I was suspecting that you are using an Esprit 100ED like me.

It might just be a characteristic of the telescope, especially when imaging in RGB, NB the stars look much tighter which is expected. It is still not a Tak at the end the day, even though it is a SUBERB scope.

What I usually include in my workflow, is a few rounds of a VERY slight saturation curve on the stars alone. This brings out the color in the halos a bit more. If I then still find them to be a bit overwhelming, I run the star reduction script of Bill Blenshen.

I hope that helps.

CS
David
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Evan Boyle avatar
Evan Boyle avatar
Thanks for your insight guys, it's super helpful! I'll be sure to use Arcsinhstretch and check it out!

Thanks for your kind words David, I definitely am prone to some self-criticism sometimes smile That's definitely good advice, I'll try bumping up the saturation a bit more. It's good to know other Esprit users have had similar thoughts and I'm not the only one! Maybe I'll just have to upgrade to a Tak then smile

Thanks again for you help Andrea and David! 
CS
Evan
Dale Penkala avatar
Dale Penkala avatar
Hello Evan,
I tend to agree with Andrea & David, I think your stars look pretty good actually and I have the same scope and at one point the same camera until I upgraded to the 2600mc pro. As far as color goes here is a suggestion for you to try and add color rather then bumping up the saturation in curves or the process of “saturation” itself.

Once I go starless and work on the star layer I’ll add my color by pulling 2 luminance’s from it. What I like to do with the 1st luminance is use morphological transformation and dilate it by about .4-.6 convolute that maybe .2-.3. Apply that as a mask. 
Then I take the second luminance and use that in LRGB combine. I adjust my Saturation slider from .38-.45 depending on how much I want to add color. Usually I’ll add 2-3 times back at .38 and slowly decrease until I’m happy with the color. Once I’m done I like to use a very slight convolution just a touch to smoothen out the star. You’ll find that it blends really well when you add the stars back to the starless layer. (Thats if your not already doing so) 

Once you start to get color coming the way you like it. Remove the mask run SCNR on the star layer and then use the “CorrectMagentaStars” script at the default setting of .40. Once you’re done pull another luminance. Put your dilated mask back on and final tweak your color from there.

Once I got the color to where I’m happy I’ll invert the mask an go into Curves and pull the saturation back on the background. Again helps to make the blend to the starless much nicer.

Just my suggestion is all.

Dale
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Evan Boyle avatar
Evan Boyle avatar
Wow, thank you so much for such a detailed and helpful response, Dale! I really appreciate you taking the time to impart your knowledge 🤩
I'll have to read your method a few more times and try it out in Pixinsight on some of my older targets to really understand it but by the sounds of it (and by looking at your images here on AB), it'll work a treat!

Thanks again!

Have a great day!
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