Question

Is there a way, on the server, to tell if a request for an image like:

http://www.myserver.com/test.jpg

is a direct request (entered in browser address bar), or as a result of an image tag?

<img src="http://www.myserver.com/test.jpg" alt="blah blah">

Answer 1

You could check the Referer field in the request to identify whether or not the image was requested directly or was referred by another page; however, this won’t allow you to differentiate between an embedded image and a linked image.

Edit: Also, as noted by tmuguet, it is extremely easy to spoof or obscure the referer in a request.