What's the TagMeNot?

This is the TagMeNot:
This black and white square pattern is a QR code tag. It encodes the address of this website, and directs here every time it is read by a QR-code reader. Any recent cellphone with a camera can decode such images. See here for QR-code decoders. See here for details on qr-codes and how thy work.

What does it mean?

Wearing, displaying or sticking this tag on some object expresses the will of the wearer or the owner that no personal information linked to pictures of that person or object has to be disclosed, such as face details, plate number, personal identity, or any details that can be linked to the wearer/owner identity.

It does not mean that the object or person cannot be photographed. This depends on local privacy regulations. TagMeNot is not a privacy enforcement tool, but only a privacy enhancing technique.

It's an universal (works everywhere), explicit (anyone can understand it's meaning), proactive and anticipative (you state your will in advance) and anonymous (no need to register) opt-out measure.

How does it work?

The QR code displayed in a picture, if properly read, can link to this site, where it states permanently some will about that picture.
It allows:

• people who want to enhance their on-line privacy, to express their will.
• people who take pictures in public spaces, to respect their subject's privacy desires.
• companies (like Flick, Google Street View or Facebook) who publish massive amounts of images, to automatically spot images that can raise privacy issues. Please consider that until now none of them has expressed the will to do so.
• organizers of public or semi-public events to help their guests to express privacy concerns.

What is Face Recognition?

Under the terms "Face recognition" are a collection of techniques, as automatic face detection, face matching, identification and verification, that in various degrees identify people through their faces.

You can read more about face recognition techniques and related privacy issues on this page: Face Recognition Privacy