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I have a windows 8 laptop. My desktop background is very dark (almost black) and when i have no windows open, my brightness dims. When i open an application that is primarily white (google chrome's start page) or just a white image, the screen brightens. It seems to be caused by the color of the screen. If i open http://www.fanhow.com/images/1/10/Green_Storm_Fill_Black_Color.jpg and zoom in and out, when the black image is small, the screen brightens, when it gets bigger, the screen darkens.

I have most likely ruled out "Adaptive Brightness" because I do not have an ambient light sensor.

Is this a feature?

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What brand of laptop do you have? I know the Dell I'm using also has an adaptive brightness, regardless of the fact it does not have a light sensor. It just changes brightness of the screen depending on how much white/black is shown at that moment. Whenever I switch from a very dark to a very bright website I notice and increase/decrease in screen brightness. I'm running Windows 7 by the way. –  Matthias Jan 23 '13 at 7:24
    
That is the same with me. Is this a feature? –  agz Jan 24 '13 at 20:27
    
I believe it's a feature on some screen models, yes. –  Matthias Jan 25 '13 at 14:25
    
This article lists the 3 types of adaptive brightness in Windows 8 & 8.1. You should disable them one-by-one (and reboot) to totally rule-out adaptive brightness. –  harrymc Nov 29 '13 at 19:44
    
You might find something useful in superuser.com/questions/187302/… –  lserni Nov 30 '13 at 0:21

3 Answers 3

Short answer: It is a feature.

This is the effect of either Intel's "Display Power Saving Technology" or AMD's "Vari-Bright" feature, the intent is to reduce power usage by reducing brightness when you look at dark images (which ostensibly would not need to be back lit so much). This technology detects whether the screen is displaying a mostly dark or mostly light image, and adjusts the back light accordingly. Unfortunately this can be annoying if important parts of the UI are light colors (like Chrome), or when dealing with highly visual applications (Photoshop, Media, etc) where changes to brightness have a negative effect on visual fidelity.

So yes, this is a feature, unfortunately this means either dealing with the effect, or forfeiting the power savings it produces.

If you dislike this feature, it can be disabled (or adjusted) it in the settings for your graphics card.

Intel:

The exact layout of Intel's options may vary from system to system, but on my machine:

Intel system tray icon > Graphics Properties > Power > On Battery > Display Power Saving Technology

It shouldn't be too hard to find, even if it ins't in the same place on your machine. You may need to look for the properties in control panel.

AMD:

Open the Catalyst Control Center (search for "CCC" in start, choose CCC - Advanced) > Graphics > Power Play > Enable Vari-Bright [Check-box] [Source]

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I have AMD, not Intel hardware, and I encounter the same thing. (See my comment on the question) –  deleteme Dec 2 '13 at 17:31
    
@gparyani I did a little research and AMD has a very similar technology (which I have edited my post to address), you may find this helpful: h10025.www1.hp.com/ewfrf/wc/… –  zeel Dec 2 '13 at 19:11

My laptop does exactly the same thing. It's a display panel "feature" (not Windows 8 fault), Dynamic contrast . Maybe a badly implemented one.

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The answer is correct but unfortunately unhelpful for when your laptop is plugged in, as Intel doesn't allow you to change the setting for AC power. Here's something else to try.

The registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000 should have a value named DCUserPreferencePolicy.
Contrary to its name, it seems to affect the AC behavior as well.
I think the top half of the number is for AC power. So you might have something like 0x00220020. The bottom 0 means this feature is disabled for DC power, so I think changing the upper half to mirror the lower half (that is, to 0x00200020) should fix it. In my case, I just set the whole thing to 0 because I didn't particularly care what it was. You can try that or something else.

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