Restrict direct image viewing

[eluser]Chris Williams[/eluser]
I'm not sure how to approach this. Maybe I can get some pointers/resources to help me with this.

Okay, I don't want images viewable from where they get uploaded to the site.

Code:

<img src="/upload/2008/06/05/10.png" />

because this photo was marked private and associated to a db record, I'd LOVE to be able to refer to it as this

Code:

<img src="/user/a.png" />

"user" is a field value and "a" is another field value.