@article {69,
	title = {Toward Practical Smile Detection},
	journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence},
	volume = {31},
	year = {2009},
	month = {11/2009},
	pages = {2106-2111},
	chapter = {2106},
	abstract = {<p><span style="color: rgb(68, 68, 68); font-family: {\textquoteright}Lucida Grande{\textquoteright}, Verdana, sans-serif; font-size: 14px;">Machine learning approaches have produced some of the highest reported performances for facial expression recognition. However, to date, nearly all automatic facial expression recognition research has focused on optimizing performance on a few databases that were collected under controlled lighting conditions on a relatively small number of subjects. This paper explores whether current machine learning methods can be used to develop an expression recognition system that operates reliably in more realistic conditions. We explore the necessary characteristics of the training data set, image registration, feature representation, and machine learning algorithms. A new database, GENKI, is presented which contains pictures, photographed by the subjects themselves, from thousands of different people in many different real-world imaging conditions. Results suggest that human-level expression recognition accuracy in real-life illumination conditions is achievable with machine learning technology. However, the data sets currently used in the automatic expression recognition literature to evaluate progress may be overly constrained and could potentially lead research into locally optimal algorithmic solutions.</span></p>
},
	keywords = {Algorithms, Artificial intelligence, Automated, automatic facial expression recognition research, Biological Pattern Recognition, Biometry, Computer simulation, Computer vision, Computer-Assisted, Face, Face and gesture recognition, face recognition, feature representation, human-level expression recognition accuracy, illumination conditions, Image databases, Image Enhancement, Image Interpretation, image registration image representation, learning (artificial intelligence), machine learning approaches, Machine Learning Models, n Humans, object detection, practical smile detection, Reproducibility of Results, Sensitivity and Specificity, Smiling, Subtraction Technique, training data set, visual databases},
	issn = {0162-8828},
	author = {Whitehill, J. and Littlewort, G. and Fasel, I. and Bartlett, M. and Movellan, J.}
}
@article {44,
	title = {Towards social robots: Automatic evaluation of human-robot interaction by face detection and expression classification},
	journal = {Advances in Neural Information Processing Systems},
	volume = {16},
	year = {2004},
	pages = {1563-1570},
	chapter = {1563},
	author = {Littlewort, G. and Bartlett, M. and Chenu, J. and Fasel, I. and Kanda, T. and Ishiguro, H. and Movellan, J.}
}
