While waiting for my new 3nm narrowband filters I decided to test my setup to its limits by attempting to capture a group of small galaxies in RGB under suburban light pollution.  This was my third target and something of an afterthought after two others and the frames were captured mostly after midnight over nine nights in late November and early December 2021.  Out of about 350 3 min subframes, only 198 survived selection and preprocessing, mainly due to thin high altitude clouds passing through.  As expected, many of the subframes looked awful due to light pollution and dust motes that I could not process away before completing the stacking process.  The new Pixinsight script to normalize scale gradients helped a lot.  The final picture is a product of curiosity rather that astro imaging as an art form.  I thought the three bright spots in the larger galaxy NGC3550 at the centre of the picture were stars or cruddy data until the catalague revealed that this is a multiple, presumably colliding, galaxy system.  While most of the galaxies were around 450 million light years away, I was awed that the tiny galaxy PGC1851758 in the upper right corner was over a billion light years away.

Processing in Pixinsight:
Blink to remove the most obvious bad subs
WBPP to calibrate, cosmetic correct and register subs
Normalize Scale Gradient script to standardize light pollution gradients
Dynamic Crop
Mure Denoise Script
Deconvolution with external PSF, starmask and masked background 
Dynamic Background Extraction with 4 -10 manual sample points 
MultiScaleLinearTransformation (masked) with Logn large scale transfer function to clean up the background on each channel.
RGB combination after LinearFit on Green channel followed by Background Neutralization and Photometric Colour Calibration
TGVDenoise (masked- 500 iterations) on LRGB image and MultiscaleMedianTransform (masked- 6 layers) to reduce noise from small and large structures.
Final adjustments with Curves Transformation and Morphological Transform

Subs in final image: