Is there an alternative to Redshift and F.lux which only dims the screen?

I want one where it reduces the screen's brightness, either by time or on demand (I don't mind). I have onboard Intel graphics. I don't want it to be like Redshift where it changes the screen's hue.

On a computer with Ubuntu 11.04 and onboard Intel graphics this works for me:

$ xrandr | grep connected | cut -f1 -d" "
VGA1

Use the output name found (in this case "VGA1") and adjust the brightness

$ xrandr --output VGA1 --brightness 0.7

Note, that the xrandr man page has this to say about the --brightness flag:

However, this is a software only modification, if your hardware has support to actually change the brightness, you will probably prefer to use xbacklight.

The development build of Redshift will alter brightness. I am not sure if it will alter based on the time but you could ask the developer to add this feature.

http://bazaar.launchpad.net/~jonls/redshift/trunk/revision/153

Here are the basic steps required and the INSTALL file has more detailed instructions about building from source.

1. You will need to install the following packages:

   sudo apt-get install build-essential libtool automake autopoint
   

2. From the Terminal get a copy of the latest development source code:

   bzr branch lp:redshift
   cd redshift
   

3. Create the configure file, compile and build:

   ./bootstrap  
   ./configure 
   make
   

4. Test the created application works as exepected:

   ./src/redshift -b 0.1
   

5. Install the application:

   sudo make install
   

This maybe https://launchpad.net/brightness ? It uses the webcam as a sensor to adjust screen's brightness. (It uses OpenCV and you have to build it by your own)