IMO - There are a number of programs out there to process astro images. I use PixInsight others use Star Tools or Nebulosity and others like Photo Shop. Most have trial periods.
I'm not going to talk about the difference much. It's kind of one of those things that you must decide where you will put your time in to learn. All we can do is inform and recommend from our experiences.
I personalty ended up with PixInsight (PI) after buying Star Tools a trial period using Nebulosity. I ran across a free youtube video set by Mitch (AstroDude) who was teaching PixInsight for Absolute Beginners. This series of videos prompted me to try PI. The twelve video set allowed me to process successfully my first image with excellent results right out of the bag. I had a set of images of M42 Orion Nebula I had taken. I down loaded the trial version and followed along in Mitch's videos and produce this as my first image processed successfully. Since that time I've been hooked on PI.
Lately I've been watching a fellow named Shawn Nielsen at visibledark.ca who is putting out some nice free little short youtube video's on using some of the PixInsight processes.
Having these "PixInsight Videos for Idiots" made PI happen for me where there was no way it would have before. PI is a very powerful image processing program. However, it's not cheap at 268 USD. It's a one time price with support updates at no cost. Still, I consider it worth every penny. BTW - Photoshop is also pricey as you pay yearly fee's to use it plus the cost of any astro add on's. Trevor Jones of AstroBackyard uses PS.
Many, Many people use PhotoShop and Nebulosity and swear by them. If you already have PS it might be worth it to you to buy one of the dozen or so astro add on programs available for use with PS. By far, I suspect PixInsight is the most popular and with the largest feedback and support base followed by PS. Some people use both!
Investigate the major programs and pick the one you like. Find that one that works for you. Most of us go thru a few before we do. I suggest looking at videos available and concentrate on the ones that make sense to you then try them out by doing a sample image process.
Oh yes, before I forget. Here is your galaxy... M51 The Whirlpool Galaxy with about two hours and half hours of stacked data. Not a the best image collection for reasons I won't go into here but, PI saved the day and it resulted in a fairly nice image still. More work can be done in PI to fix the problems.
Have fun with your imaging. There will be ups and downs so just remember...it's a hobby and enjoy it.
Edited by scadvice, 27 March 2020 - 03:29 PM.