A comprehensive survey on facial micro-expression: approaches and databases

Over the past few years, the importance of the facial micro-expression (FME) has garnered increasing attention from experts because of its potential applications from the judgment court to the psychology research centers. A real challenge for developing an extensive system of the FME analysis is to select a suitable method and a database. In this manuscript, we have conducted a comprehensive and comparative survey to address the aforementioned challenge, and to give clear guidelines to alleviate further researches. To come up with this task, we have justified each method in terms of its pros and cons, which are meant to be beneficial for researchers choosing a method or a database, which suits their context application. Also, we have exhaustively analyzed the whole framework of the FME system by decomposing its pipeline into the pre-processing, the feature extraction, and the classification.