Have you ever done an imaging session and wanted to add more detail in certain areas, but didn't have any more subs of the same size and with the same camera and optics, but you did have some from a different set?
It took me a long time to finally use the Projects feature in PixInsight but now, I always use this feature when I am ready to do image processing on any Astro imaging project data.
I’m willing to bet that if you’re using dedicated astro image processing software, you’ve at some point run across a capability of the software that does something called image analysis.