Master Page-Changing Header matching for each page

Question

Hi,
In my master page, I want to CHANGE MY HEADER IMAGE ACCODING TO THE CURRENT PAGE which the user is visiting. For each page I have each image. How can I change the header for each page in the master page? For example, I have an image for the registration(reg.aspx) page, I have another image for the products(prod.aspx) page, I have another image for the purchase (pur.aspx) page and so on.
Any clue!