F.lux is a new tweak available for iDevice owners that allows users to change the color of their screen depending on the time of day they use the terminal. The idea behind this tweak came from the way our terminals change their screen brightness and color tone, the developers of F.lux promising that by using this tweak we will protect our eyes against too strong colors. Practically F.lux allows us to change the tonality of the colors for day/night so that we can set warm/cold colors in various tones for our device depending on the environment in which we use it.
Select the type of lighting in the room you're in at night, and then forget about it. Each evening at sunset, f.lux warms up the colors on your phone. At dawn, f.lux returns your phone to daylight colors. We made f.lux because one day we noticed that all our laptops were the wrong color temperature at night. They looked fine during the day, but at night, they were much too blue. We realized that looking at the sun all night long might not be such a good idea. After researching blue light's effects on health, we found lots of evidence that color matters even more than brightness. And it turns out that timing matters, too: Blue light during the day is great for your circadian rhythm. Blue light at night is not.
Sleep researchers have just begun studying the effects of night-time use of laptops, cell phones, iPads and other devices that emit blue light. Evidence suggests that even just a little extra blue light at night can keep you awake later and negatively affect the quality of your sleep. Our users say that f.lux prevents eyestrain. They also say that it's easier to wind down and go to sleep after using a f.lux-enabled device at night. Plus, you'll never glow blue in a restaurant again. You can use f.lux because it makes you sleep better, or you could use it because it just makes you look better. Either way your eyes will thank you.
From the iOS Settings application, we can set the color tone of the screen at night so that when the ambient light detects an environment with low brightness, it will automatically activate the color tone chosen for our screen. We can also set the speed of the transition between the screen color for the tweak, so that for old devices it is necessary to set a longer transition period and for new ones a shorter period. F.lux is available for free in Cydia in the BigBoss repo and is compatible with all iDevices.
After installation: open Settings and tap f.lux. Choose your lighting type and transition speed (for older devices the long transition is instant to avoid flickering). By tapping each lighting option you can see a short preview of how your screen will look like after sunset. If your screen appears orange, open settings and select a different lighting type. f.lux should make your phone look just like a book under your room lighting. f.lux should have a minor impact on your battery life. f.lux itself uses less than 2 seconds of CPU each day, but Location Services can be a larger drain. We are currently working to optimize battery usage. f.lux uses a low power mode to determine your location. We don't record or track where you are – there's no server on our end.
The current version of f.lux requires Location Services to be enabled. If you install it with Location Services off, a reboot or reinstall is required to make f.lux work. iPhone 3g support is experimental and may slightly shift your colors during daytime. If you don't like the shift, uninstall f.lux and reboot your phone to restore normal colors. You can turn f.lux off at any time by choosing "Off" under the Enabled option in f.lux settings.
