Windows is automatically adjusting the brightness of the screen based on the background color of whichever windows is open. When toggling between dark/light background the brightness will decrease/increase respectively. This is not tied at all to the lightning
conditions of the room, and I've been able nail down that this only happens when two conditions are met (but it it 100% reproducible under these conditions) 1. Laptop is running on battery, and 2. screen brightness slider is adjusted to the lower brightness
settings approximately up to about 30-40%.
I've tried eliminating every possible variable that I can think of, including diagnostic startup through msconfig. This automatic brightness adjustment occurs regardless of the program or window involved, but here is an example where i've cut out everything
and simply toggle between the Windows Desktop (with background set to black) and Windows Explorer (white background).
EXAMPLE 1: Desktop (black) is up, no programs loaded. I open Windows Explorer (white) and the brightness gradually fades brighter for a period of about 5 seconds, tick-tick-tick-tick-tick brighter. I minimize Windows Explorer (returning to black background)
and the brightness gradually fades darker, tick-tick-tick-tick darker. When working in a blacked-out room this constant increasing/decreasing of brightness very annoying. Note that the brightness slider is set to the minimum setting this whole time (at approximately
40% the automatic fading is no longer noticeable to the point of annoying, although it is still present, but 40% is much too bright for a blacked-out room).
EXAMPLE 2: I open two tabs in either Google Chrome or Internet Explorer (happens for both, and all other programs for that matter), in one tab the webpage has a dark background (grey/brick/whatever) while the other tab has a light background (white/yellow/whatever).
As I toggle between the tabs the brightness will decrease after switching to the darker background and increase after switching to the lighter background, fading tick-tick-tick-tick-tick over about 5 seconds each time.
Since this only happens on battery it should be just a simple setting in Power Options, but I have not yet located such and option. I would appreciate any ideas, and I can supply further information if needed. Two solutions would be acceptable
A) brightness remains constant at the level I set it regardless of whether laptop is plugged in or on battery.
B) brightness adjusts in one single "jump" when toggling between light/dark backgrounds, rather than fading over 5 seconds.
Thanks for your assistance
