Intel iMac screen too bright - any software solution?

Have you try the Brightness Applet?
http://library.gnome.org/users/gnome-power-manager/stable/applets-general.html.en

To add it: Right-click on the gnome-panel - Add to panel - search the Brightness Applet and then "Add"

Thanks for the suggestion. I tried it but it doesn't work. Maybe it is only meant for laptops?
This really seems like a bad oversight by Apple.
I will keep an eye out for a solution.

https://help.ubuntu.com/community/MacBook2-1/Jaunty

Thanks actionparsnip.
I tried these also but without success. They seem to be written for MacBook and I have an iMac desktop computer.
Never mind, thanks for the suggestion.

Hi Everthon Valadão. Thanks very much. The 'LinuxScrew' solution was no good to me but in the first solution I tried the gamma altering command line thing and it worked well enough for me.
I really couldn't understand the other stuff about macros and keys but I may figure it out eventually.
In the meantime I will just have use the Gamma thing in Terminal each time I log on.
So thanks again for your help. Excellent.

If you create a small script you can then add the script to your logon commands so it gets run automagically.

Have a look in system -> Prefs -> Startup Programs

A script looks like this:

#!/bin/bash
<some commands here>

basically open your favourite text editor, type "#!/bin/bash" without the quotes on the top line and press enter, then write out commands that you want to happen. The last line must be carridge return ended (press enter on the last command you enter). Save the file as whatever you wish. Some people like to use .sh extension sto show its a SHell script but file extensions mean nearly nothing so you can use anything you like.

You now must make the text file into a scipt by marking it as executable with:

chmod +x <file>

If you want, you can put it in /usr/bin and it will be accessible from anywhere as it is in your $PATH

you can then bring up the startup items as I outlined earlier and tell your system to run the script after you log on.

No more manual running then, its all done for you :D

Thanks, actionparsnip, you are very kind to take the time for this.
I do not see how anyone could make it any clearer but for me it still looks like a challenge.
I will certainly give it a try.
Thanks again, very much.