f.lux is a small freeware utility for Mac OS X and also Windows that changes the color ‘temperature’ of your display based on the time of the day.
In the daytime, when the surrounding lighting is sunlight, the screens are designed to look ‘blue’, which give a feeling of a higher temperature and thus, look like the sun. But at night when you are inside a dark room with fluorescent or incandescent lighting, which are obviously dim compared to sunlight, having a display with a ‘blue’ background is not the best idea for the health of your eyes.
A slightly yellowish or reddish tint makes the color temperature of your display more ‘cooler’ which is suitable for a situation in which your Mac’s display is a poorly lit environment.
As soon as the sun goes down, f.lux changes the color ‘temperature’ of your display to look like the indoor lighting that you’re using. You can choose from 4 options for the kind of indoor lighting you have –
- Tungsten: 2700K
- Halogen: 3400K
- Fluorescent: 4200K
- Daylight: 5000K
- Disable for an hour: 6500K
Color temperatures are mentioned in Kelvin (K).
You can also set the transition time for the change of temperature to give your eyes more time to adjust to the change. You have 2 transition options –
- Fast (20 seconds)
- Slow (1 hour)
Similarly, in the morning at sunrise, your screen transitions back to a color temperature which is more blue, or more brighter.
I, personally have been f.lux for about an year now, and I can’t imagine how I ever lived without it. Sometimes, when you open the lid of your laptop at night, the display is so bright and ‘warm’ in temperature, you need to cover your eyes at first. f.lux fixes that, by making your display cooler and ‘redder’.
f.lux is not suitable for advanced color and design work. If you are working on something that requires accurate perception or editing of colors, f.lux has a handy option called “Disable for an hour”. This returns the temperature of your display to the Mac OS X default, and will automatically transition back to your f.lux predefined setting after 60 minutes. You can setup f.lux to run automatically on startup, by checking a simple box from the Preferences.