ioreg -lw0 | grep IODisplayEDID | sed "/[^<]*</s///" | xxd -p -r | strings -6
This gives you e.g. the following information:
The first line is the LCD model number, the second is the active color profile.
If you google the LCD Model number, you can find out more about your screen (contrast ratio, brightness).
For my screen (build into a 1st generation Macbook build in 8/2006) I get the following information:
Info about B133EW01 Screen Model