Red Filter for Screen [duplicate]

Possible Duplicate:
Is there a software utility to adjust screen gamma/brightness/contrast?

If I'm stargazing or just working at night, I'd like to be able to dim the laptop screen and filter to red. I can dim the screen, but it is still quite bright. What can I do on Ubuntu to do this? (Settings or software.)

3 Answers

Redshift is a small program which allows to change display's color temperature according to time of day - i.e. make it more reddish in the night and blue-ish during the day.

You can see if setting a really low "night" color temperature produces a desired result.

If you want to set the color temperature manually, you can use the "one shot" mode of the program:

redshift -o -t 3700:3700 -l 0.0:0.0

and to reset the color temperature back:

redshift -x

It is also possible to toggle day/night mode using the gtk-redshift indicator.

This may not be exactly what you are looking for, but I use a program called f.lux to automatically lower the color temperature of my screen after sunset. The temperature is configurable, and it knows when to activate itself by your latitude and longitude which you must input yourself.

There is also an open source program that provides the same function called redshift. Redshift doesn't work for me, but I know people who prefer it.

You could try the tool that comes with the proprietary graphics driver. In the ATItool, I can change e.g. the level of the rgb channels, that should work.