SAN FRANCISCO — Let’s say a real estate agent takes a gorgeous photo of an iconic landmark in her town. She puts it on her website and uses it to spruce up her community page. But months later, she finds that same photo on someone’s website without her permission, and the owner won’t take it down. Or say an agent takes a photo for a listing that expires, but he later finds that the new agent is using his photo to market the same property. In each case, the agent owns the copyright to the photo, so he or she can sue — right? Not so fast. The agents can call an attorney, but they’re unlikely to be able get representation if the photo is not registered with the U.S. Copyright Office, according to panelists at the “Watching Out for Copyright Infringement and Other Legal Traps” …