Windows – How to switch off auto brightness on a Lenovo W530

I'm not seeing this effect myself (white/black Paint windows), and you've probably tried this already, but how about the Automatic Display Brightness setting in the Intel HD Graphics Properties (Advanced mode)?

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Especially if it's in a dark room, it sounds like what a smartphone's 'light sensor' would do: when it's darker, turn down the brightness. When it's lighter, turn up the brightness. In a dark room, the increased brightness from a white screen might cause the sensor to see the whole room became brighter, a kind of feedback loop. And when the screen is black, the whole room becomes darker, causing the screen brightness to be lowered.

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 isn'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]