Hi Rolf,
Webcams can be very weak in the blue and as you don't seem
to use a filter (IR at least), the image could be very red/ green dominant?
A lot of my modded webcam star field stuff had bad IR halos
without using an IR rejection filter.
Your image seems to be free of that though.
Have you done any G2V star calibrating? A lot of that field is
predominantly reddish stars.
Steve