Semisupervised learning of classifiers: Theory, algorithms, and their application to human-computer interaction

Ira Cohen, Fabio G. Cozman, Nicu Sebe, Marcelo C. Cirelo, Thomas S. Huang

Research output: Contribution to journalArticlepeer-review


Automatic classification is one of the basic tasks required in any pattern recognition and human computer interaction application. In this paper, we discuss training probabilistic classifiers with labeled and unlabeled data. We provide a new analysis that shows under what conditions unlabeled data can be used in learning to improve classification performance. We also show that, if the conditions are violated, using unlabeled data can be detrimental to classification performance. We discuss the implications of this analysis to a specific type of probabilistic classifiers, Bayesian networks, and propose a new structure learning algorithm that can utilize unlabeled data to improve classification. Finally, we show how the resulting algorithms are successfully employed in two applications related to human-computer interaction and pattern recognition: facial expression recognition and face detection.

Original languageEnglish (US)
Pages (from-to)1553-1567
Number of pages15
JournalIEEE transactions on pattern analysis and machine intelligence
Issue number12
StatePublished - Dec 2004
Externally publishedYes


  • Bayesian network classifiers
  • Face detection
  • Facial expression recognition
  • Generative models
  • Semisupervised learning
  • Unlabeled data

ASJC Scopus subject areas

  • Software
  • Computer Vision and Pattern Recognition
  • Computational Theory and Mathematics
  • Artificial Intelligence
  • Applied Mathematics


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