I've been having this issue with my (relatively new) Dell XPS. When I'm playing a game, the image can go from bright in one area to dark in another area. While I believe that's normal in some parts of the game (i.e. I go from say a outdoor environment to maybe inside a cave), it happens in other parts of the game as well and the change from dark to dim (or dim to dark) in both cases is so sudden that it doesn't look normal. This has happened with at least two of the games I have played on my laptop, and I'm not exactly sure what the issue is but I think it has to do with the lighting effects in the games.
I don't know if I have those features enabled on my laptop (not sure how to check), but I can say that I haven't installed any special software like that or adjusted any settings. Sorry if I'm unclear, I not familiar really with computer hardware. But my laptop is pretty new and it's a Dell XPS L702 if that helps. Or if you could possibly tell me how I can check for those features.
Laptops have dimmers on the screen, because they drain battery power fast. You will likely find the options somewhere in the power controls within the control panel.
I've also noticed on my brother Dell laptop, that the F keys are defaulted to special functions rather than F1-F12. There is a bright and dark setting on a couple of the F keys. Do you think you might be accidentally hitting the F keys with that control on them?
I don't believe it's a power issue because the areas that go from bright to dim are always the same spots. For example, when I'm playing an FPS and I'm looking at a spot that goes dim, if I turn away from that spot it gets brighter but if I turn back to that spot its dim again. I'm not sure if I'm explaining it clearly but the problem seems to be that it goes from dark to dim or vice versa so suddenly between areas that it's kind of a strain on the eyes.
Also the only buttons I press are asdw when I play FPS or the numbers 1-0 when I'm playing an rpg.