You know those really unflattering photos on Facebook that you untagged at lightning speed? Now might be a good time to delete them...or at least check up on one new privacy setting.Yesterday, security firm Sophos issued a warning saying that Facebook rolled out a feature that recognizes your face in photos, prompting your friends to tag you. Some Facebook users in the United States have had this feature since it was first announced in December. The difference: During the beta, there was no setting to opt-out of appearing in tag suggestions. As of yesterday's rollout, however, you must now adjust a setting in order to opt-out.According to Facebook, this facial recognition feature uses a comparison of photos you're tagged in to suggest that friends tag you in new photos. The site says that this feature is intended to save you time: Instead of tagging the same friends in 25 photos you just uploaded, you can now apply one label to multiple photos in one step.Facebook reiterates that only friends can tag you in photos, you'll be notified when someone has tagged you, you can remove a tag whenever you want and that tag suggestions are based only on photos you've allowed yourself to be tagged in.Here's how you can opt out of this feature.Facebook Facial Recognition: How to Opt OutFacebook has automatically opted you in to this new facial recognition feature, which means your friends will see suggestions of photos in which to tag you, unless you change the setting.To turn off this feature, go to "Account ," then "Privacy Settings" and select "Customize settings." In the second section, "Things others share," click "Edit Settings" next to "Suggest photos of me to friends."