Sensors 2013, 13(12), 16682-16713; doi:10.3390/s131216682
Article

Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems

1email, 1email, 1email, 2email and 1,* email
Received: 28 October 2013; in revised form: 30 November 2013 / Accepted: 2 December 2013 / Published: 5 December 2013
(This article belongs to the Section Physical Sensors)
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Abstract: Over the last decade, human facial expressions recognition (FER) has emerged as an important research area. Several factors make FER a challenging research problem. These include varying light conditions in training and test images; need for automatic and accurate face detection before feature extraction; and high similarity among different expressions that makes it difficult to distinguish these expressions with a high accuracy. This work implements a hierarchical linear discriminant analysis-based facial expressions recognition (HL-FER) system to tackle these problems. Unlike the previous systems, the HL-FER uses a pre-processing step to eliminate light effects, incorporates a new automatic face detection scheme, employs methods to extract both global and local features, and utilizes a HL-FER to overcome the problem of high similarity among different expressions. Unlike most of the previous works that were evaluated using a single dataset, the performance of the HL-FER is assessed using three publicly available datasets under three different experimental settings: n-fold cross validation based on subjects for each dataset separately; n-fold cross validation rule based on datasets; and, finally, a last set of experiments to assess the effectiveness of each module of the HL-FER separately. Weighted average recognition accuracy of 98.7% across three different datasets, using three classifiers, indicates the success of employing the HL-FER for human FER.
Keywords: face detection; GHE; facial expressions; PCA; ICA; LDA; HMMs
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Siddiqi, M.H.; Lee, S.; Lee, Y.-K.; Khan, A.M.; Truc, P.T.H. Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems. Sensors 2013, 13, 16682-16713.

AMA Style

Siddiqi MH, Lee S, Lee Y-K, Khan AM, Truc PTH. Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems. Sensors. 2013; 13(12):16682-16713.

Chicago/Turabian Style

Siddiqi, Muhammad H.; Lee, Sungyoung; Lee, Young-Koo; Khan, Adil M.; Truc, Phan T.H. 2013. "Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems." Sensors 13, no. 12: 16682-16713.


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