Different header image for archive page

My users are asking me to provide a smaller header image when they view posts so that when printing them, they don’t have to use as much ink. How does one accomplish this? All pages but the ones that show the entire text should have the standard image.

I have searched through the forum archives but don’t understand what to do. It appears that single.php is the correct page but I don’t know what to do from that point on.

Thanks