1. OpenCV class description: adaptiveThreshold. Internet (2010),
http://opencv.willowgarage.com/documentation/cpp/imgproc_miscellaneous_image_transformations.html?highlight=threshold#adaptiveThreshold
2. OpenCV class description: canny. Internet (2010),
http://opencv.willowgarage.com/documentation/cpp/imgproc_feature_detection.html?highlight=canny#Canny
3. OpenCV class description: matchShapes. Internet (2010),
http://opencv.willowgarage.com/documentation/cpp/imgproc_structural_analysis_and_shape_descriptors.html#matchShapes
4. OpenCV class description: threshold. Internet (2010),
http://opencv.willowgarage.com/documentation/cpp/imgproc_miscellaneous_image_transformations.html?highlight=threshold#threshold
5. Introducing OpenNI. Internet (2011),
http://openni.org