If you have your computer running 24/7 with a webserver program running on it with your photos linked through a website or just as a directory list. You might be able to use an ftp server, but the client (a.net) won't necessarily open it and display it. Beware, however, that if you then get lots of people trying to download the photo from your computer then your ISP
might get stroppy about bandwidth and your computer might object/hang.
AFAIK, you won't be able to have a link to file://c:myphoto.jpg, or whatever because that will only refer to the local computer (as far as a.net is concerned).