Those settings helped on the re run. I m posting the 5x5 image. There is only one area on the right hand side of some star misshape, and one area where there is flaring to the top right of the Pacman nebula. I'll be able to fix these once stretched. This is just a simple histo stretch and a small contrast tweak for the screen. TomLum 25 pane APP Astro 1 post

Here is the 25 pane version, used with the DBE files. Very good blending result for brightness, gradients and detail. Two areas of overlapping show star distortion.  Whether these can be joined without issues by other settings I m noy sure yet. More testing to do. This took 3 hrs on the laptop to put together. TomAPP-Cassiopeia-25-Lum-blend-from-DBE-frames-histo16b-1600

Let me try that initial image again16-pane-Lum-DBE-test-2k

Zoomed in version. I stretched the final image to show the Non linear version.16-pane-Lum-zoom-registration