For all I have heard, reducing the screen brightness of your phone can increase your battery life. Just about every expert in the field agrees to this statement. But today I came across this article which kind of raised quite a few questions in my mind. The excerpt from the article in question here is:
All these screen dimming/color cast applications function in essentially the same way: by overlaying a graphic on the screen to reduce the brightness and/or change the color cast of the screen. Think of it like adding a partially opaque layer to an image in Photoshop. When you tell the Lux application, for example, that you want the screen 50 percent dimmer than the actual hardware in the phone can provide via LED adjustments, the application essentially cheats by layering a gray mask over the screen that decreases the brightness because the screen elements are darker. Other apps like Screen Adjuster, Darker, Easy Eye, Twilight, and even the brightness adjustment function in popular battery-saving app JuiceDefender all work the same way.
So if the screen brightness applications (like Lux) only add a partially opaque layer they are essentially not dimming the backlight (correct me if I am wrong here) so in turn it would not have any affect in battery life. Right?
The article continues saying – Anything that layers something over the screen in anyway disables the “Install” button as the button is rendered unclickable in order to prevent malicious software from creating a false overlay that leads the user to think an application has a different set of permissions or that the application is an entirely different app altogether. So does reducing the screen brightness via Settings uses some other technique (probably it actually reduces the backlight)?