M55 Sagittarii

Processed using APP, PixInsight with WBPP, SPCC, BXT, NXT, SXT, ImageBlend, GHS, and Affinity Photo 2.

I used WBPP to process exposure-time groups and then APP to combine them. Rather than RAS, I applied Adam Block's technique of using ImageBlend to combine an unstretched copy with a MaskStretched copy in order to directly control the superimposition of the brightest stars onto the star mass.