*2.2. Face Detectors*

We perform experiments on the fusion of six face detectors: the four detectors tested in [9] (the canonic VJ algorithm [14], a method using the Split up sparse Network of Winnows (SN) classifier [31], a modification of the VJ algorithm with fast localization (FL) [34], and a face detector based on Discriminative Response Map Fitting (DRMF) [32]), as well as two additional face detectors (the VJ modification using NPD features (NPD) [33] and a high-performance method implemented here: http://dlib.net/face\_detector.py.html. In the following, this latter method is called Single Scale-invariant Face Detector (SFD). Each of these face detection algorithms is briefly described below.
