1. 正负样本不均衡的问题
CNN 中样本不均衡的问题:http://caffecn.cn/?/question/20
http://www.shuang0420.com/2017/06/20/%E5%8D%B7%E7%A7%AF%E7%A5%9E%E7%BB%8F%E7%BD%91%E7%BB%9C-%E7%9B%AE%E6%A0%87%E6%8E%A2%E6%B5%8B/
https://www.leiphone.com/news/201706/ONG92KrSNoyKiHe1.html
2. 正负样本划分
http://www.cnblogs.com/rainsoul/p/6247779.html
https://stackoverflow.com/questions/25598335/collect-negative-samples-of-adaboost-algorithm-for-face-detection
http://www.doc.ic.ac.uk/~sgc/teaching/pre2012/v231/lecture10.html