Facebook, the world's most popular social networking site, has rolled out a facial recognition technology to identify people in photos uploaded on its website, but the feature has stirred up controversy due to privacy issues.

The Palo Alto, California-based company silently launched "tag suggestions" out over the last several months, and the feature is now available in most countries. It will be debuting the app to users in the United States over the next few weeks.

The feature has stoked concerns from users, privacy advocates, regulators and lawmakers as the feature is enabled for all 600 million users by default and suggests people's names to tag in pictures without their prior consent.

100 million tags per day

"Every day, people add more than 100 million tags to photos on Facebook. They do it because it's an easy way to share photos and memories," the Palo Alto, California-based company said.

A feature of Facebook's Photos application is the ability to "tag", or match faces and friends. If a photo contains a user's friends, the user can tag his friends in the photo. These tags can be identified to particular areas of the photo. When the image is displayed, the tags become hyperlinks to the profile of the subject of the tag. Facebook briefly notifies the subjects of the tag, and the subjects can untag themselves from the photo. When photos of a person are displayed, this display includes their own photographs and those published by others and tagged with that person's name. Each tagged friend has the option to untag himself from a photo at anytime. Only friends can tag each other.

According to Facebook's Justin Mitchell, many users have complained that tagging photos can be a chore. "Like that time you had to tag your cousin and her fiance over and over and over again in 64 different pictures of their engagement party, and then go back and tag the guests," he cites.

Since October, Facebook has been working to make the tagging process easier for users. Facebook first added group tagging, so users could type one name and apply it to multiple photos of the same person.

Now Facebook has added "tag suggestions", which is designed to make "tagging multiple photos even more convenient." The new app uses facial-recognition software to match new photos to other photos the user has been tagged in. The software groups similar photos together and, whenever possible, suggest the name of the friend in the photos.

"Now if you upload pictures from your cousin's wedding, we'll group together pictures of the bride and suggest her name. Instead of typing her name 64 times, all you'll need to do is click "Save" to tag all of your cousin's pictures at once. By making tagging easier than before, you're more likely to know right away when friends post photos," Facebook's Mitchell said.

Disabling the feature

The face-recognition tool is enabled for all users by default.

If for any reason you don't want your name to be suggested, you will be able to disable suggested tags in your Privacy Settings. Just click "Customize Settings" and "Suggest photos of me to friends." Your name will no longer be suggested in photo tags, though friends can still tag you manually.

You can also request that Facebook remove the summary of what your tagged photos have in common. On the Privacy Settings page, click Customize settings and use the controller labeled, "Delete Photo Comparison Data" if the user doesn't want it to be stored. This won't untag photos you're tagged in but will delete the summary information drawn from comparing any tagged photos of you.

Privacy concerns

Facebook's face-recognition technology has already spread controversy due to a number of privacy issues. Among the concerns raised is that the face-recognition function is activated by default, when it should have been an "opt-in" feature to allow users to choose. The tagging function has also been slammed for allowing tags without requiring the subjects' prior consent. Also a concern is that Facebook has built a potentially sensitive image profile database of its millions users.

Regulators have launched probes to see if the new face-recognition app has broken any regulations. Among those that have launched investigations are the European Union data-protection regulators, and the Ireland data protection authority.

"Tags of people on pictures should only happen based on people's prior consent and it can't be activated by default," Gerard Lommel, a Luxembourg member of the Article 29 Data Protection Working Party, told Bloomberg News.

The technology could lead to a "dangerous" collection of data, Handelsblatt cited Bernhard Freund, a consultant at Germany's data protection watchdog, as saying.

Facebook acknowledged it "should have been more clear with people during the roll-out process when this became available to them."However, a Facebook spokesman Andrew Noyes told The Wall Street Journal the company has received "almost no user complaints," suggesting "people are enjoying the feature and are finding it useful." He said Facebook had made the disabling feature "easy and explained how to do so on our blog, in our Help Center, and within the interface."

This is not the first time Facebook has faced scrutiny from privacy advocates. Facebook previously had plans to make users' home addresses, mobile phone numbers and other personal information available to websites and application developers. However, Facebook suspended the plan after facing several objections from U.S. lawmakers and others.

Pros and Cons

People join Facebook in order to share life and experiences with friends and family near and far. The new tagging tools make sharing of photos with friends less tedious.

To address privacy issues, users can set their privacy controls to allow access to anyone, to their friends, or to members of their networks. They can also customize privacy settings for photos and albums. They can disable the facial recognition function. However, most Facebook users still don't know how to set their privacy options.

PROS:
* Tagging multiple photos of the same people is more convenient and saves more time.
* Only friends can tag other friends in photos.

CONS:
* Photos of you that you might not want tagged will be tagged, as you can't pre-approve tags.
* You can only untag photos manually.
* Risk of mistaken identity as there are billions of photos in the database and other people can tag your photos.
* More people you don't want seeing your photos could have access to them.
* You need to turn off the app if you don't want your photos suggested.

Do you agree with Facebook's decision to make the facial recognition feature automatic for all users? Would you disable this feature? Tell us what you think. Write your comments below.