I edited the nightside view, adding a new field of stars, toned down seriously the "glowy" (external light) effect of the civilization lights, edited manually the lights distribution (less on coast, more inland).

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The source from which I extracted the pixel distribution to be illuminated can't easily give me more distribution (there aren't that many different color tones).
So I went for manual edition (my original idea was to rely only on filters, rendering and pixel selection).

It would probably be better with a source with more contrasts and numer of tones.
Something to remember for me