Paper Info
Title
Fully automated age-weighted expression classification using real and apparent age
Abstract
After decades of research, automatic facial expression recognition (AFER) has been shown to work well when restricted to subjects with a limited range of ages. Expression recognition in subjects having a large range of ages is harder as it has been shown that ageing, health, and lifestyle affect facial expression. In this paper, we present a discriminative system that explicitly predicts expression across a large range of ages, which we show to perform better than an equivalent system which ignores age. In our system, we first build a fully automatic facial feature point detector (FFPD) using random forest regression voting in a constrained local mode (RFRV-CLM) framework (Cootes et al., in: European conference on computer vision, Springer, Berlin, 2012) which we use to automatically detect the location of key facial points, study the effect of ageing on the accuracy of point localization task. Second, a set of age group estimator and age-specific expression recognizers are trained from the extracted features that include shape, texture, appearance and a fusion of shape with texture, to analyse the effect of ageing on the face features and subsequently on the performance of AFER. We then propose a simple and effective method to recognize the expression across a large range of ages through using a weighted combination rule of a set of age group estimator and age specific expression recognizers (one for each age group), where the age information is used as prior knowledge to the expression classification. The advantage of using the weighted combination of all the classifiers is that more information about the classification can be obtained and subjects whose apparent age puts them in the wrong chronological age group will be dealt with more effectively. The performance of the proposed system was evaluated using three age-expression databases of static and dynamic images for deliberate and spontaneous expressions: FACES (Ebner et al., in Behav Res Methods 42:351–362, 2010) (2052 images), Lifespan (Minear and Park in Behav Res Methods Instrum Comput 36:630–633, 2004) (844 images) and NEMO (Dibeklioğlu et al., in: European conference on computer vision, Springer, Berlin, 2012) (1,243 videos). The results show the system to be accurate and robust against a wide variety of expressions and the age of the subject. Evaluation of point localization, age group estimation and expression recognition against ground truth data was obtained and compared with the existing results of alternative approaches tested on the same data. The quantitative results with 2.1% error rates (using manual points) and 3.0% error rates (fully automatic) of expression classification demonstrated that the results of our novel system were encouraging in comparison with the state-of-the-art systems which ignore age and alternative models recently applied to the problem.
Year
DOI
Venue
2022
10.1007/s10044-021-01044-1
Pattern Analysis and Applications
Keywords
DocType
Volume
AFER, Automatic age-group estimation, Automatic FFPD-based RFRV-CLM, Age features effect on AFER
Journal
25
Issue
ISSN
Citations 
2
1433-7541
0
PageRank 
References 
Authors
0.34
11
3
Name
Order
Citations
PageRank
Nora Al-Garaawi100.34
Tim Morris200.34
Timothy F. Cootes34358579.15