[1] http://vc.cs.nthu.edu.tw/home/paper/codfiles/hkchiu/201205170946/Histograms%20of%20Oriented%20Gradients%20for%20Human%20Detection.pdf
[2] https://cs.brown.edu/~pff/papers/lsvm-pami.pdf
[3] https://pdfs.semanticscholar.org/d78b/6a5b0dcaa81b1faea5fb0000045a62513567.pdf
[4] https://github.com/cmusatyalab/openface/blob/master/openface/align_dlib.py
[5] http://lijiancheng0614.github.io/scikit-learn/modules/decomposition.html#randomizedpca
[6] https://arxiv.org/abs/0909.4061