Well, the solution I usually use is to make a function called img() (or similar). I.e.,
$SETUP[imageURL] = 'http://www.host.com/images/';
function img($imgName) {
global $SETUP;
return $SETUP[imageURL] . $imgName;
}
Now i can use this like;
print '<img src="'.img('icon.gif').'">';
Alternately you could ofcourse print from img() instead of return, so an img('icon.gif'); outputs <img src="http://www.host.com/images/icon.gif">, but if you need extra parameters, and include images as backgrounds for tables, body or whatever, this becomes a hazzle (for me anyway).