modifing image before outputting to video out interface

[Nikita Orlov]

Hello!

I have a such question. I have some modern ATI card (I still don`t have it, I can buy any model) and Linux PC.
Linux has X.org. I want to modify image right before it is going to output like VGA, DVI and others.

So, I suppose there is buffer with RGB data, and I can do some processing with it.
I hope there is some place in drivers, where I can put some my modification code.
Is it possible?

Another question the same, but in this case I don`t use X.org, but FB.
I think it has same solution, but I don`t know.  

-- 
Nikita Orlov
Skype: nik_stet
QQ: 2717846083