The website I am working on uses an image defined in CSS as the main logo. The html code looks like this:
Something.com | The best something ever
set the image as the background of your h1 (set the width/height so it fits) then set your text-indent to something crazy like -9999px. That way when css is disabled (such as being crawled) the bot will see the text in the header instead of the background.
example:
CSS
#myHeader {
width:200px;
height:50px;
background: url('lcoation/of/the/image.jpg') top left no-repeat;
text-indent:-9999px;
}
HTML
...
HELLO WORLD
...