http://en.wikipedia.org/wiki/Feature_extraction
http://en.wikipedia.org/wiki/Interest_point_detection
http://en.wikipedia.org/wiki/Feature_detection_%28computer_vision%29
http://en.wikipedia.org/wiki/Feature_%28computer_vision%29
https://docs.google.com/a/cin.ufpe.br/file/d/0B90h4PbCASuJZVlTbzZhem9QWmM/edit
http://eduardoverasousa.wordpress.com/2012/03/01/processing-e-convolucao/
http://en.wikipedia.org/wiki/K-nearest_neighbor_algorithm