Introduction To Face Device

A face device is a system to acquire a set of digital data
samples representing a human face. As the human face
is a complex 3D object, the data can be in several
forms: a 2D image where the gray levels of the pixels
represent the projected reflectance of the face surface
under visible illumination; a 2D image where the gray
levels of the pixels represent the projected reflectance
of the face surface illuminated with an active source;
a 2D thermal image representing the heat emitted by
the face surface; 3D samples of the surface structure.

Face devices can be distinguished on the basis of
the data dimension if it is active or passive. Face
devices can be passive, i.e., based on the passive reflectance
of ambient light by the body, or active, i.e.,
associated with an energy emitter and a sensor to

capture the energy reflected by the face. The data
captured can be either in 2D or 3D form.

A face device can be based on different technologies,
depending upon the data to be captured and the
signal to be obtained. The most applied face devices
include a video camera to capture 2D images of the
face and a digitizer to sample and quantize the analog
signal generated by the camera. Different face devices
deliver different signals to be digitized into 2D or 3D
data. The data captured can be stored under different
file formats for subsequent processing.

Current face biometric systems are based on the acquisition
and processing of image data, representing a
human face. A face acquisition device is typically
a video camera capable of acquiring single images or
video streams of data, representing a face. As the face is
a 3D object, the acquired data can represent either the
2D projection of the face reflectance on the image
plane or a set of 3D samples of the face structure,
possibly with the associated reflectance. In the former
case, a conventional video camera can be used to
acquire images of face. In the latter case, a more complex
3D acquisition device must be applied.