You probably already know that Facebook collects a ton of your data. However, did you know that Facebook can even detect information about you in the photos you upload? A new Google Chrome extension shows you exactly what labels Facebook has assigned to your pics.

The extension, called Show Facebook Computer Vision Tags, was created by software engineer Adam Geitgey. The tool shows a simple visual key in the upper right corner of each Facebook pic with a list of data points that Facebook has extracted from the photo. For instance, a picture of a baseball stadium included the words stadium, crowd, outdoor, sky and baseball.

Geitgey said he built the tool in only about an hour, noting how the simple feature could help users learn more about what Facebook already knows about them.

“I think the feature that Facebook can detect objects is really interesting and really useful, especially if users are blind, but a lot of users don’t realize how much info is being collected about them,” he said. Geitgey also compared Facebook’s data collection to the small fees you pay to withdraw from an ATM, saying, “at the time, you think it’s worth the fee for the convenience. But if you look at end of year it might add up to a lot more than you might think.”

While it’s obvious that Facebook collects the data that we provide to it in writing, it’s much more surprising that the site can even read our pictures for information.