increase brightness on a linux text console

[Thierry ITTY]

Hello

I have several linux servers running in text mode only 
the PCs have verious kind of video cards
some display normal, some display dark, and some very dark

I need a command line program to increase the brightness (or gamma) so that
I can read the text displayed without switching all lights off !

Is there some kind of standard vga tool for that or do I need to look among
specific make and models utilities (I have mainly ATI cards) ?

tia

PS please CC me at thierry.itty at besancon.org
			- * - * - * - * - * - * -
Bien sûr que je suis perfectionniste !
Mais ne pourrais-je pas l'être mieux ?
	Thierry ITTY
eMail : Thierry.Itty at Besancon.org		FRANCE