Brightness goes down for the whole screen, when windows with dark backgrounds are enlarged

Question

The brightness of the whole screen goes down considerably when I enlarge windows with a dark background (Gnome-terminal and TTYs for example, as well as Games, especially when in fullscreen). It's up to a point sometimes that the text on TTYs is only barely visible. The brightness goes up again if I put other windows (like a regular Firefox-window) in front or when I make the "problematic" windows smaller. It also happens if a Browsser-window shows lots of dark/black background, but it seems that the effect is more severe the more of that darkness is shown.

I use Ubuntu 12.04 and nVidia-drivers 302.17 (problem occured for many months, with 11.10 and older nVidia-drivers as well).

Solution

This sounds like it's your monitor. Some monitors have a feature called "dynamic contrast" which basically adjusts the backlight based on what's on the screen. This way they can claim in their advertising that it has a ridiculously high contrast ratio. It may look nice in some places, depending on your preference.

You can probably turn this off. Fiddle with the controls on your monitor and there should be something about dynamic contrast in the menu. (On my Samsung T240, the option is under Picture / MagicBright).

Comments

[Mrokii]

It was indeed my monitor, ty. That "Dynamic Contrast" option was hidden within a menu named "MagicBright" (a Samsung monitor).

[Marco A.]

I had the same problem, it was called X-Contrast on my Hanns-G monitor

[user4035]

Thank you! Same problem here with Phillips. It tortured me for 2 weeks until I looked at monitor settings.