Darker (Screen Filter) is an app that lets you lower your Android screen's brightness to a level of extreme darkness. Why would you want to do this? To save battery and give your eyes a break, of course.
In the settings, you can choose the exact brightness you want for your screen. If you don't want to set the brightness manually, you can set the minimum brightness for your device instead.
In addition to lowering the brightness, with Darker (Screen Filter), you can set filters with different colors. These filters aim to help keep your eyes from getting tired too quickly. Again, as with the first option, you can set the intensity manually.
Darker (Screen Filter) is an interesting app if your eyes get tired from looking at your screen. The only problem, of course, is that it's difficult to see the screen if you set it on the darkest levels.
