The LCD in your monitor is a filter, that controls what colors from the white back-light reach your eyes.
It is not completely effective - when the LCD is set to block all colors, there is some white-ish leakage as you say. A completely red shape on an LCD would still have some blue in it from the leakage. We perceive color and brightness relative to the other colors close by.
Flux shifts the color balance of the screen towards red at night. After your eyes get used to it, the colors look about right, but the LCD is in fact blocking a higher proportion of blue than normal.
What it does not do is change the brightness of the screen - this is usually done by changing the intensity of the backlight. It is bad for you to look at a screen that is either too bright or too dark for the room you are in, so this is best done with an actual light sensor.
Here is a thread about doing that, but neither of the programs in it work very well. If you fancy making an open source program to do this, you'll be my hero :-)
It is not completely effective - when the LCD is set to block all colors, there is some white-ish leakage as you say. A completely red shape on an LCD would still have some blue in it from the leakage. We perceive color and brightness relative to the other colors close by.
Flux shifts the color balance of the screen towards red at night. After your eyes get used to it, the colors look about right, but the LCD is in fact blocking a higher proportion of blue than normal.
What it does not do is change the brightness of the screen - this is usually done by changing the intensity of the backlight. It is bad for you to look at a screen that is either too bright or too dark for the room you are in, so this is best done with an actual light sensor.
Here is a thread about doing that, but neither of the programs in it work very well. If you fancy making an open source program to do this, you'll be my hero :-)
http://superuser.com/questions/284706/webcam-as-ambient-ligh...