that works, but probably a better technique is to put in a normal h1 and assign the image to background of that element. then use text-indent to thow the display of the text off screen (as is commonly done). like this:

h1 { background-image: url(foo.png); text-indent: -999em; }

of course, you then have to give dimensions to the h1 to show the whole picture, but i leave that as an exercise for the reader.