I think the answer to this is no, but ideally I would like to be able to allow image hotlinking, but redirect regular links. For example, if somebody uses this, it should work as expected:
<img src='http://mysite.com/image.jpg'/>
But if they use this, it would redirect to a different page upon visiting:
<a href='http://mysite.com/image.jpg'>Click Here</a>
I believe $HTTP_REFERER
is the same, regardless of the two methods. Is there any other clever way to distinguish between the two?