Face detection refers to the science of locating the faces of people in a scene. It is a critical element of focusing software in cameras, as well as the primary step in facial recognition in unconstrained scenes: the face must be detected before it can be compared to known faces and identified. It can also be used by newer software to organize photos on your computer.
On cameras, face detection helps establish how the focus should work in a picture. Depending on the camera, face detection technology can identify at least 10 faces in a scene. Once they are identified, they can be prioritized, and the focus can automatically adjust to feature the high priority faces. The camera’s face detection is often shown to the user through a series of one or more rectangles overlaid on the scene. With the face detected, the technology can also adjust the exposure to make sure the subject is properly shown, including compensating for dark scenes or scenes with an illuminated background.
There are current and projected uses of face detection and recognition — sometimes called facial biometrics — for crime fighting and security. For example, face detection and recognition technology can help prevent car theft by being employed at secured parking lots. The idea is to match the face of the person who brought the car to the lot to the face of the person removing the vehicle from the lot.
Additionally, face detection and recognition technology has already been attempted as laptop security. That is, the registered user’s face may be needed to unlock the computer, or the computer may shut down when the user leaves his or her work station. In 2009, some such systems were proved to be breachable by security researchers who were able to use both a photograph of the computer user and Photoshopped images to defeat the log-on security.
For organizing photos, Apple® has created an iPhoto® feature called Faces. Faces uses face detection to identify people’s faces in photographs on a user’s computer and then uses face recognition to match faces that appear to be the same person. With this collection, the user can then easily add a name to a group of photos or find photos of a particular person.