Star reduction techniques

[EC48675 (Euan)]

I've recently got into trying star reduction in photoshop on my images, and so far I've only tried the Astronomy Tools Action Set for photoshop. It does an alright job, but I'm wondering what other people do to really get the target to stand out more and not be overwhelmed by the star size.

What are some other ways to reduce stars?

[Camelopardalis (Dunk)]

Blur XTerminator is pretty effective at reducing the star size, but you could use free tools such as StarNet2 to extract them, and reduce them to taste.

[Geochron (Jon)]

I think the Astronomy tools action only works on the whole image - is that correct? If so it will definitely have limitations. If you can you really need to separate the stars and the nebulosity first using either Starnet++ (free) or RC Astro Star Exterminator (paid). If you have a look at the RC Astro site you can download a Photoshop action which (once you have purchased the Star Exterminator plug-in) will produce 'stars' and 'starless' layers in Photoshop at the 'press of a button'....

Once you have a 'stars only' layer then there are a multitude of ways of reducing their intensity but perhaps the simplest is just to move the middle slider around in the Levels dialog. Adjust to taste. Cheap and cheerful

Another thing which is relatively straightforward, once you have the hang of separating stars and starless images, is to produce two different versions of your image, one with a minimal stretch and the other with your normal stretch. If you extract the star layer from the minimal stretch and combine it with the starless layer from the normal stretch this has the effect of reducing the star influence on the combined image.

There are plenty of other more complex recipes out there for this (and also for recombining the star and starless layers effectively) so it is really just a matter of finding something that best suits your workflow....

cheers, Jon

[EC48675 (Euan)]

Thanks so much! I'll try those techniques out once the weather finally clears!

[Startrek (Martin)]

I’m one of very few on IIS who don’t use the popular and traditional Astro software like PS , PI to process their deep space images.
I use Startools which is a totally different animal ( active signal evolution tracking) but does a superb job at Star correction and Star reduction . There are a few modules which can either dampen down your Star field or directly reduce Star size and brightness.

https://www.startools.org/modules/repair

https://www.startools.org/modules/magic

Unfortunately due to Startools being an active tracking process it’s best to use it autonomously from start to finish. If you just use it for one or two modules and continue in another software like PI , then you loose its signal to noise tracking capabilities. It can be done but not recommended

Cheers
Martin

[AstroViking (Steve)]

If you are an Affinity Photo user, the set of macros by James Ritson include several for star manipulation.

I tend to use the 'Star Size Reduction' on the most (formerly known as "Star Eater"), followed by the star luminosity and/or brightness macros.

Cheers,
V.

[PRejto (Peter)]

There is a different way if you just want to make larger stars look better one at a time. Check out "liquify" in photoshop. You find this under filters. Then select Pucker (4th down on left side) and adjust the brush size to just get around the star. It's quite effective! (But, if you have spikes on your stars this is not the way to go!....thanks to Adam Block for this method).

Peter

[JA]

Originally Posted by EC48675

I've recently got into trying star reduction in photoshop on my images, and so far I've only tried the Astronomy Tools Action Set for photoshop. It does an alright job, but I'm wondering what other people do to really get the target to stand out more and not be overwhelmed by the star size.

What are some other ways to reduce stars?

Aside from software means , other (more fundamental / pre-capture) ways to reduce star size / bloat include....

1. Use Narrowband filters to replace some/all of the RGB channels
2. Stop down the optic/lens with an aperture mask or via an iris
3. Change the optic to a less aberrated optic

Best
JA

[Premordial (Max)]

Starnet works for me. It's part of my workflow within Siril.

[2CRAZY (Heath)]

Originally Posted by Camelopardalis

Blur XTerminator is pretty effective at reducing the star size, but you could use free tools such as StarNet2 to extract them, and reduce them to taste.

Thanks, I was also wondering about this, will give this a try next time.