Semi-supervised estimation of perceived age from face images

We address the problem of perceived age estimation from face images and propose a new semi-supervised age prediction method that involves two novel aspects. The first novelty is an efficient active learning strategy for reducing the cost of labeling face samples. Given a large number of unlabeled face samples, we reveal the cluster structure of the data and propose to label cluster representative samples for covering as many clusters as possible. This simple sampling strategy allows us to boost the performance of a manifold-based semi-supervised learning method only with a relatively small number of labeled samples. The second contribution is to take the heterogeneous characteristics of human age perception into account. It is rare to misregard the age of a 5-year-old child as 15 years old, but the age of a 35-year-old person is often misregarded as 45 years old. Thus, magnitude of the error is different depending on subjects' age. We carried out a large-scale questionnaire survey for quantifying human age perception characteristics and propose to encode the quantified characteristics by weighted regression. Consequently, our proposed method is expressed in the form of weighted least-squares with a manifold regularize, which is scalable to massive datasets. Through real-world age estimation experiments, we demonstrate the usefulness of the proposed method.