The short answer is no.

The helpful answer is that readdir gets its information from the local filesystem, which you don't have access to unless you're running programs on that machine (this is generally construed to be a good thing). What your scripts can see of the filesystem of a remote machine depends entirely on what kind of access you have: are you relying entirely on a webserver? If so, you're limited to what the server wants to tell you about the remote directory structure, and you have to take it in the format that the server offers it to you (in which case, LWP and possibly HTML::Parser are worth a look).

Why do you want to serve up images off a remote server? There might be a better way to accomplish what you're looking to do, if you provide a few details...