Nikita Misiura has created a neat program to create starless images. Here is a page to find out more about the program: https://www.astrobin.com/397290/
Follow this link to Nikita’s download page for the PixInsight Starnet++ processes: https://sourceforge.net/projects/starnet/ You can then install the Starnet++ program as a resident PixInsight process. I am using the command line version for macOS. If you want to try the command line versions for Starnet++ then you have to go to this page: https://sourceforge.net/projects/starnet/files/ Click on the “v1.1” link and then download either the Window, macOS or Linux version. I haven’t run the Windows command line version. If you have some experience with the Linux or macOS terminal, running these versions is very straightforward. The “readme.txt” file tells you everything you need to know to run the program.
The macOS version that I use contains a mono and a color version of the program. In my experimentation I have found that I like the results of the mono version better than the color version. Perhaps I haven’t done enough experimentation to find the correct size of image to use or how to optimize the “stride” parameter. Here are a few examples using mono_starnet++. All of the examples are h-alpha narrow band images.
Click on the images to see a higher resolution version.