.. _liveness:

Real-time Face Liveness Detection
======================================


To spot fake faces and prevent photo attacks, use the integrated 2D anti-spoofing system that distinguishes a live face from a face image. Due to the analysis of not one, but a number of frames, the algorithm captures any changes in a facial expression and skin texture. This ensures that it is a live person in front of a camera and eliminates the possibility of fraud using images on paper or mobile device screens.

The liveness detector estimates a face liveness with a certain level of confidence and returns the confidence score along with a binary result ``real/fake``, depending on the pre-defined liveness threshold. 

To enable the face liveness detector, do the following:

#. Open the ``findface-video-worker`` configuration file. In the ``liveness`` --> ``fnk`` parameter, specify the path to the face liveness detector model as shown below. 

   .. code::

      sudo vi /etc/findface-video-worker-cpu.ini

      [liveness]
      #------------------------------
      ## path to liveness fnk
      fnk = /usr/share/findface-data/models/faceattr/liveness.v3.cpu.fnk


      sudo vi /etc/findface-video-worker-gpu.ini

      [liveness]
      #------------------------------
      ## path to liveness fnk
      fnk = /usr/share/findface-data/models/faceattr/liveness.v3.gpu.fnk

#. Restart ``findface-video-worker``.
 
   .. code::

      sudo systemctl restart findface-video-worker-cpu
      sudo systemctl restart findface-video-worker-gpu

Once the face liveness detector enabled, the ``findface-video-worker`` service will be posting face liveness data to ``findface-facerouter`` in the ``liveness`` key of the ``detectorParams`` dictionary. To process a face due to its liveness, :ref:`write a plugin <plugins>`.