How Facebook Photo Tags Work

screen capture of facebook photo tagging page
: Photo tagging is a great way to identify folks in images. But if you have dozens of people in those pictures, the chore of tagging may leave you wishing you had fewer friends.
Screenshot by Nathan Chandler

Without photos, Facebook would likely have been a passing Internet phase, relegated to a dusty corner of the Web where text-based Web sites go to die. But photos are everywhere on Facebook, and as of January 2011, the site housed more than 90 billion images, making it the largest database of pictures on the Web [Source: Quora]. Some estimates show that site visitors will be uploading around 6 billion photos per month by the middle of 2011 [Source: Mashable].

Photo tagging is a major reason that Facebook pictures are so popular. Tagging basically means that after you upload a picture of your friends at a party, you click their faces, one by one, and type their names in the Who Is This? box to identify who is who in the image. Months or years later, this feature makes it very easy to find every photo featuring, say, your friend Brianna, with a single click.


But tagging can be laborious, especially if there are a lot of people in each picture. In part to make this process quicker and easier, Facebook introduced Tag Suggestions in early 2011.

Whenever Facebook offers up an image for you to tag, Tag Suggestions automatically fills that troublesome Who Is This? box with its best guess as to who the person might be. The site can do this thanks to the power of facial recognition technology.

In short, after a photo hits Facebook, the site uses an algorithm to scan the image for faces. Then it attempts to match those faces with other tagged people in your albums.

The technology isn't perfect, but it does often work very well. As a result, it can save you hours of your life that you used to spend tagging pictures. This feature also might make you majorly freak out, depending on how you feel about personal privacy and the Internet.

Regardless of your stance on privacy, if you're on Facebook (or anywhere in public where a surveillance camera of any kind might see your face), Tag Suggestions and facial recognition capabilities are worth understanding. Keep reading and you'll see more about how this kind of advanced software can benefit your Facebook life, and how you can best keep it under your control.


Tagging and Untagging Pictures for Facebook

screen capture of Facebook's Tag Suggest option
With Tag Suggestion, you don’t even have to find the faces. Facebook automatically pinpoints human faces and prompts you to name them.
Screenshot by Nathan Chandler

Photo tagging is a bit like a childhood game of tag. You race around in your image collection, tagging as many of your friends as quickly as possible. Only on Facebook, this isn't so much a game as it is a part-time job. That doesn't stop people from doing it. Photo tagging is hugely popular, at around 100 million new tags each day [SOURCE: Facebook].

After you upload a series of photos, Facebook loads the Edit Photos page. Here, you can type descriptions (captions) for each image, choose a photo for the album cover, delete individual images, move pictures to various albums, and of course, tag photos.


To tag an image, you simply click the person's face, and then begin typing his or her name. To expedite this task, Facebook begins guess what you're typing, which makes tagging go much more quickly.

If you use Tag Suggestions, your tagging job is even easier. After you upload a picture, Facebook immediately loads the Who's In These Photos? page, and highlights any faces that appear in the pictures. You simply begin typing the person's name, and if you're friends with that person on Facebook, the site auto-completes the name, not only for that picture, but for any others in which that person appears.

Tagging a friend sends them a notification so that they know there's a new image of them online. They also have the option of untagging the picture so that their account isn't associated with the image.

Of course, if the picture is embarrassing, they can't remove it – a major drawback to the public nature of Facebook. But by being nice to your friends and choosing to leave humiliating pictures offline to begin with, you'll keep a lot more friends and spare yourself from any acts of online (or perhaps offline) vengeance.

If a friend tags you in a photo and you want to remove the tag, you can. In your account profile, click photos, and scroll down to see the section titled Photos and Videos of You. Click a picture with you in it, and below the image, click Remove Tag.

When it comes to pictures of you, you may want to disable Tag Suggestions altogether. To do so, from the Account drop-down menu, click Privacy Settings, click Customize Settings. Go to Things Others Share and next to Suggest Photos of Me to Friends, click Edit Settings, and click Disabled.

Those are the fine points of using Tag Suggestions. On the next page, you'll read more about this technology that helps Facebook put names to faces.


Facebook Face Recognition

young man with strange expression
Changes in facial expression are just one variable that can totally confuse automatic recognition technologies – and your mother, too.

Facial recognition technology is anything but new. Law enforcement agencies have been using these kinds of systems for years to build searchable image databases of known and suspected criminals and terrorists.

Facebook hasn't made public any details regarding the developer behind its recognition tool. But it's safe to say that this capability is similar to those in other consumer programs, such as Windows Live Photo Gallery, iPhoto, and Picasa, all of which have handy facial recognition features.


If you've used a point-and-shoot digital camera made in the past few years, you may have seen facial recognition technology at work. Many current cameras highlight faces using boxes, which indicate that the auto-focus is keeping those faces sharp and crisp. That's facial recognition at work.

Similarly, when you upload a picture, the Tag Suggestion feature finds faces in your pictures. Then it highlights those pictures and immediately prompts you to type a name. Suggested tags work only within your list of closer friends and not friends of friends.

To work their magic, facial recognition software relies on complicated algorithms driven by hardcore mathematics and clever programming. The application analyzes each image for specific characteristics, such as pixel values or gradients (the way images transition from dark to light areas), and other numerically precise data.

Then it makes (often very accurate) guesses as to which parts of the image corresponds to a human face. That part of the technology is pretty dependable. Matching a name consistently to the correct face is trickier.

That's because variables such as lighting, facial hair, and facial expressions can fool the software. This is evident in Facebook when Tag Suggestions confuses your friends and suggests the wrong names. But the technology is continually improving, and soon it will work no matter how bushy and wild you let that mustache grow.

For privacy-minded people, the implications of this technology are scary. It's possible that someday soon, a total stranger might take a photo of you from afar, enter that image into a search engine, and within minutes, know who you are, where you live, and a whole lot of other information you'd rather not disclose.

So use Facebook's Tag Suggestions feature to ease your tagging workload, but be sure to keep your guard up. Stay up to date on the seemingly endless changes Facebook administrators make to both tagging and privacy settings, and always keep questionable images off the Internet entirely. Doing so will keep you ahead in the game of Facebook fun and keep you safer, too.


Lots More Information

Related Articles

  • Brown, Mark. "Facebook Silently Rolls Out Face Recognition Tagging to the World." June 8, 2011. (July 22, 2011)
  • Geuess, Megan. "Facebook Facial Recognition: Its Quiet Rise and Dangerous Future." April 26, 2011. (July 22, 2011)
  • Geuess, Megan and Sarah Jacobsson Purewal. "Facebook's Facial Recognition Flops." June 15, 2011. (July 22, 2011)
  • Kumar, Neeraj et al. "Describable Visual Attributes for Face Verification and Image Search." (July 22, 2011)
  • Livingston, Connor. "How Facebook Facial Recognition Works." July 17, 2011. (July 22, 2011)
  • McLaughlin, Laurianne. "Facebook Facial Recognition Flub: Not Enterprise Grade." June 9, 2011. (July 22, 2011)
  • Mitchell, Justin. "Making Photo Tagging Easier." The Facebook Blog. June 30, 2011. (July 22, 2011)
  • O'Reilly, Tim. "Facebook's Face Recognition Strategy May be Just the Ticket." June 9, 2011. (July 22, 2011)
  • Olivarez-Giles, Nathan. "Facebook Facial-Recognition Feature Draws Criticism." Los Angeles Times. June 9, 2011. (July 22, 2011)
  • Paul, Ian. "Facebook Photo Tagging: A Privacy Guide." June 9, 2011. (July 22, 2011)
  • Purewal, Sarah Jacobsson. "Google Won't Dabble in Facial Recognition System." May 19, 2011.. (July 22, 2011)
  • Purewal, Sarah Jacobsson. "Why Facebook's Facial Recognition is Creepy." June 8, 2011. (July 22, 2011)
  • Whittaker, Zack. "Facebook's Photo Facial Recognition Enabled: Time to Check Your Settings." June 7, 2011. (July 22, 2011)