Pattern recognition Face recognition Facial expression recognition Apis mellifera Automobiles Character recognition Classifiers Computer vision Facial Expressions Feature extraction Image segmentation License plate detection License plates (automobile) Non-verbal human Optical character recognition Optical character recognition (OCR) Pixel values SVM classifiers Segmentation algorithms Shape contexts Still images APIS MELLIFERA Argentina Bacterial metabolites Conditional random field Expression recognition Human emotion K-nearest neighbors classifiers Nearest neighbor search Nosema ceranae