Well, maybe, depending on what you're asking. You can make your site title an image, yes. You'd do that like this:
#site-title a {
background: url("http://starsbynight.files.wordpress.com/2012/07/molino-antigua.jpg") no-repeat scroll 0 0 transparent;
}
I took the first photo on your page and made it the background. It only fills the space that the site title takes up, though, and if you delete the text, the available space for the image goes away, too, so you'll need to add padding to the above CSS to create a block that's the right size. Something like padding: 50px; creates a upright rectangle in the middle of that space.
I'm not sure that you can make an individual page have an image that isn't used by all the pages, though.