Hiding photos on Facebook may not actually work as well as you think it does.

Picturebook, a browser extension now available in the Chrome web store, claims to allow you to "view hidden photos of anyone on Facebook"— even if you aren't friends with them.

See also: How to find old Facebook posts

Sounds like a Facebook creeper's dream, right? But though Picturebook's description is technically true, it is also misleading.

No app or browser extension — this one included — is able to change the privacy settings of someone else's photo. What Picturebook is really doing: surfacing photos that you could have seen anyway, even if a user tagged in them hid them from their timeline.

Say a friend tags you in an unflattering photo. You can make it go away by selecting "hide from my timeline." But this only prevents people from viewing the photo within your timeline; it doesn't actually remove or block the photo in any way. If the photo's privacy setting was set to "public", anyone could have found it anyway.

Other users will still be able to see the photo by visiting your friend's timeline, or simply by searching for it.Picturebook takes advantage of this loophole and surfaces photos you've been tagged in, regardless of whether you've hidden them.

In short, Picturebook makes it just a little easier to find what you could have found anyway.

It's worth pointing out that Facebook reminds users every time they hide a photo that it is still viewable from others' news feed, from search, and from other places on Facebook.

How to fix it

The only way to really hide your hidden photos from this tool is by untagging yourself. First, select "hidden from timeline" from the drop down menu under the photo's date. From there, select "Report/remove tag" from the popup window that appears, then select "remove tag."

Image: Facebook

This removes the tag, which will prevent photos from appearing on your timeline, or on the Picturebook extension. The photo itself will still appear elsewhere on Facebook; only the person who posted it can remove it.

If you're still worried about old photos showing up, now may be a good time to revisit your privacy settings, to make sure you're only sharing what you want. The social network recently made privacy settings more accessible with a new Privacy Basics page, intended to make this process easier.