A grocery store in the Czech Republic found the perfect family to promote its local delivery service. They were young, attractive, and the children had infectious smiles.

But the family had been plucked from a photo in cyberspace, and the stars had no idea they were endorsing a foreign grocer in an advertisement thousands of miles away.

Danielle Smith, a mommy blogger in O'Fallon, Mo., is not sure how to regain control over her own family photo.

It took a virtual friendship to report the digital theft.

A week and a half ago, one of Smith's Facebook friends sent her a message saying that he had seen a life-size ad of her family displayed in a grocer's window in Prague. As reported on the Post-Dispatch's parenting website, STLmomsanddads.com, that friend took a picture of the ad and sent it to her. She immediately recognized it as a photo she had posted on her blog and a few social networking sites.

"Oh, my gosh. It is life-size," she said. "You go from having a mommy website to finding your picture 5,000 miles away," she said. It was both a little flattering and a little creepy, she said.

Smith, who was previously a television reporter in Springfield, Mo., now runs extraordinarymommy.com. She has not contacted the Czech grocer and isn't sure about how to proceed.

"I don't think I'm willing to spend thousands of dollars to go after a grocery store in the Czech Republic," she said.

Privacy experts says she may have a hard time getting compensated for her family's stint as unpaid endorsers.

"Under U.S. law, permission is needed before an image or likeness is used in an advertisement," said Chris Hoofnagle, director of the Information Privacy Programs at the Berkeley Center for Law and Technology in California. It would be a simple case here: "You approach the company and say, 'Where is my money?'" he said.

It's trickier when dealing with a foreign company with no American connections.

Kimberley Isbell, a fellow at the Berkman Center for Internet and Society at Harvard University, is also a staff attorney with the Citizen Media Law Project. She says Smith could attempt to sue the company in a local court and try to get a Czech court to uphold the judgment. Or she could try to file a suit through their legal system.

"Part of the question is, do they even have the resources to make it worthwhile? Is it a small mom-and-pop grocery or the equivalent of Wal-Mart?"

Instances like these may be part of the trade-off of having a global medium to exchange information — virtually for free.

"I can be sitting at my desk reading in real-time about how China is blocking Twitter, or someone in China can download my photo and post it on a billboard," Isbell said.

In the meantime, Smith says she has learned an important lesson about posting pictures online: Always use low-resolution images (so they don't look so good when enlarged) or stick a digital watermark on the photo.