I've been doing serious astrophotography for around 20 years. I started in Seattle (large mistake), but now, I'm in Arizona, where we get a lot of "severe clear" nights.
I use a small wide field telescope that is easy to travel with, and I have a home observatory that houses a 12" scope that is designed only for photography.
Star shooters know you can spend hours getting a good picture of a galaxy or nebula. The light coming from these distant objects is dim, so it's going to be a while before those photons stack up.
There are some dedicated programs for astrophotography. PixInsight is an excellent example. I think it has been slowly winning astrophotographers over from Photoshop, but it's got a big learning curve, and many photographers who already have lots of time logged with Photoshop may stay with Adobe.
One of the things that has made Photoshop so much more pleasant to use in processing astronomy images is a series of plug-ins from Russell Croman, a former engineer, chip designer, and software guru by trade, who has put those software skills to use making plug-ins that don't work with anything else but astronomy images. The plug-ins have been so popular he's doing it full time now.
GradientXTerminator
I first bought a Croman plug-in back around 2000. It's called GradientXTerminator. It fixed a big problem for astrophotographers, and that's correcting gradients (uneven backgrounds). His solution was so good and so easy I'm still using it 20 years later. It's been through a lot of updates (all free so far) and it now supports my Apple Silicon computers.
Here's a wide shot of the Veil Nebula, with lots of gradients, and an especially bright one in the center.
Fixing this is quite simple. Open an image where uneven backgrounds are messing up your photo. Outline your image with the lasso tool. Invert the selection so you are selecting the sky, which is where the gradients are going to be.
Then, bring up the plug-in and choose how much strength you want Russell's clever algorithms to use to repair the gradients. On top of that, GradientXTerminator will balance the color of your image.
Here's the final result:
Star Shrink
Croman wasn't satisfied to only solve the gradient problem, so he went on to bloated stars. While ideally, stars should be pinpoints of light, our atmosphere and even the optics we choose can enlarge the stars, taking attention away from the subject of your image.
There are some filters built into Photoshop that can help with this, but it's better to have something that is designed solely for stars that get bloated. That's what Star Shrink does. You bring up the filter, and then adjust the stars to get the smaller ones to be pinpoints of light. You can adjust the radius of your stars and the strength of the filter. In areas where the stars are plentiful, like near the Veil Nebula, it can make a big difference. Unlike some of the built-in Photoshop solutions, it works on the whole image at once. So basically, all the stars are reduced with a click.
Here's the Veil Nebula again with a star reduction. It can help highlight the subject of your effort and help reduce distracting stars.
NoiseXTerminator
Of course, noise is one of the biggest issues with astronomical images. You're shooting in very low light, and noise is always the result.
Topaz and some others have some terrific noise reduction plug-ins, and I've used them on sky images. But Croman told me he wanted something designed for noise in astronomy images, so he did his own plug-in.
As Croman says: "NoiseXTerminator was trained exclusively on deep-sky astrophotos, so its neural network is familiar with how stars should look and the types of detail we see in our photos. It can perform natural detail enhancement without boosting noise or inventing non-existent structure."
Here's a closeup of NGC1977 in Orion. It's an old image I did many years ago, and there's lots of noise.
Giving you a web-friendly JPEG isn't the best way to see the noise, but there's plenty of it.
After running NoiseXTerminator things are much cleaner.
While Topaz and other plug-ins do quite nicely, for astrophotos, Croman's solution is a better match.
StarXterminator
This plug-in is truly remarkable. Here's Croman's explanation:
StarXTerminator uses an advanced convolutional neural network with a unique architecture suited to this task. This network has been extensively trained on photographs from a wide range of instruments, from camera lenses to the James Webb space telescope. Small stars, big stars, huge stars, and even diffraction spikes are recognized and removed, with minimal impact to non-stellar features.
I didn't think it would be all that valuable, but it is. Nebula in particular are stunning without the star background, but StarXterminator is really valuable because it lets you separate the stars and your main object on different layers, allowing you adjust the stars to your liking while leaving the nebula or galaxy untouched.
Here's my Veil Nebula again, but with the stars taken out.
Generally I'd save the stars and put them on another layer so I can process both layers independently, but these objects without stars are pretty compelling, although not accurate as to their real-world view.
Summary
If you're using Photoshop for processing, I think some or all of Croman's tools are must-haves. They can save you a lot of time and give you better results than you will likely get just using Photoshop's built-in tools. These Photoshop plug-ins also work with Affinity Photo, if that's your choice for processing.
They also work with the very sophisticated PixInsight, and Croman has produced a PixInsight only tool for sharpening called BlurXTerminator, which is getting rave reviews.
Processing astronomy images is about as challenging as image processing can be. Roman has made a tremendous contribution to the art and the science of astrophotography.
His website is here, and you can check out each plug-in and purchase any of them if you desire.
