mt1955 - 2:36 pm on Jan 16, 2009 (gmt 0)

(0) put the images in a directory outside of the webserver's scope

(1) set a cookie from the page that is going to contain the images.

(2) pass the name of the image file to a php script that will check for the presence of the cookie before outputting the image.

to get a copy of the script, search for "chill : prevent hot linking without reliance on javascript or referer"