My recommendation:
Leave Contrast and Black level at factory settings (50%) for general use.
Operate all brightness features as desired.

Some information about Advanced menu. It's not possible in this review to talk about every item - too many.
First of all, I skip fine image settings that are "reserved" for professional people.
This review is intended to illustrate how this universal machine can help regular (but demanding!) users.
Let's mention some interesting features.

To open Advanced menu, you switch the 2490 off. Then you press and hold Input button and press Power button.
The first page of Advanced menu appears.