Re-processing M13

I want to learn Synthetic Luminance. So I re-process M13 using synthetic-L.
This pic's processing is only

(1)Make Synthetic-L from R,G,B.
(2)Back ground extraction each L and RGB file.s
(3)Stretch each L and RGB files
(4)Adjust Target and Back ground colour.

No noise reduction. Lazy processing. Lol
Center's brightness is increasing without remaining star shape.
Stars colour is more natural.
But less star sharpness
One get one lost.
Our hobby is just like game.