.. _liveness:

Enable Face Liveness Detection
======================================


The FindFace face liveness detector tells apart live faces from face images. The face liveness binary result ``real/fake`` serves as one of the filters for detected face analysis during :ref:`case investigation <case-files>`. 

The face liveness detector can be automatically enabled and configured during the :ref:`installation <installer>`. If you skip this step, you can manually do so afterwards, following the instructions below.

.. note::
   The face liveness detector functions on both GPU- and CPU-acceleration. However, it is much slower on CPU. 
 

.. rubric:: In this section:

.. contents::
   :local:


Enable Face Liveness Detector
---------------------------------

To enable the face liveness detector, do the following:

#. Open the ``/etc/findface-video-worker-gpu.ini`` (``/etc/findface-video-worker-cpu.ini``) configuration file. In the ``liveness`` section, specify the path to the neural network model (``fnk``) used in the face liveness detector. 

   .. code::

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

      #------------------------------
      [liveness]
      #------------------------------
      ## path to liveness fnk
      ## type:string env:CFG_LIVENESS_FNK longopt:--liveness-fnk
      fnk = /usr/share/findface-data/models/faceattr/liveness.pacs.v0.gpu.fnk


   .. code::

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

      #------------------------------
      [liveness]
      #------------------------------
      ## path to liveness fnk
      ## type:string env:CFG_LIVENESS_FNK longopt:--liveness-fnk
      fnk = /usr/share/findface-data/models/faceattr/liveness.pacs.v0.cpu.fnk

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

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


Configure Liveness Threshold
--------------------------------

If necessary, you can adjust the liveness ``threshold`` in the ``/etc/findface-security/config.py`` configuration file. The liveness detector will estimate a face liveness with a certain level of confidence. Depending on the threshold value, it will return a binary result ``real`` or ``fake``. 

.. note::
   The default value is optimal. Before changing the threshold, we recommend you to seek advice from our experts by support@ntechlab.com.


.. code::

   sudo vi /etc/findface-security/config.py

   LIVENESS_THRESHOLD: 0.85,