Machine learning porn classification:
Yahoo Open Sourcing a Deep Learning Solution for Detecting NSFW images: https://yahooeng.tumblr.com/post/151148689421/open-sourcing-a-deep-learning-solution-for
Discussion: https://news.ycombinator.com/item?id=12614193
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Machine learning in porn industry: https://www.quora.com/Are-there-any-porn-sites-using-machine-learning
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(PDF) Adult video content detection using Machine Learning Techniques: http://colorlab.no/content/download/37238/470343/file/VictorTorres_MasterThesis.pdf