It seems that r_overbright is actually the real visual enhancment that makes everything so much brighter!
One can still use r_lightscale 2 or even higher, but r_overbright should be reduced!

do i need to open console , or must i change in .cfg file ?

In lunch options just add +r_overbright 1
Or create autoexec.cfg in game folder.

So, this stuff is not in the original DOOM 3, is it?

Wow, if this is the case... there needs to be some serious apologies for the freakout. Another post just discovered while the seceret levels for Doom 2 have been edited to remove Nazi/SS references for legalties, the levels and data are still intact for the original secret levels. in the Iwad for compatibility with doom source ports and vanilla doom 1/2 mods.

Alright, gotta go to twitter and apologize to id and Carmack for four-letter words.

That's right!
Well....I didn't mean to cause a freakout! People should control their emotions! I'm anolising the game, I'm not forcing anybogy go crazy!
And still r_overbright is another way of lightscaling, so it's not an improvement. it's not some sort of ambient lightning or global illumination.

The point is, they did add a new algorithim. The problem now is.... what the heck else did they add? I've seen some posts here suggesting it may have merged some id tech 5 code and switches... so what else is there that we dont know about yet? and does it do anything cool, lolol?

it would be beneficial to their image to make a list of technical changes so people will discontinue this nonsense