Joint Representation Classification for Collective Face Recognition
This work addresses the problem of improving face recognition accuracy and efficiency for applications involving multiple correlated images, though it is incremental as it builds on existing sparse representation techniques.
The paper tackles the problem of collective face recognition by proposing a joint representation classification (JRC) method that accounts for correlations among multiple images, unlike traditional sparse representation classification which processes images individually. Experimental results on three public databases show that JRC with a practical iterative quadratic method saves computational cost and achieves better performance than state-of-the-art methods.
Sparse representation based classification (SRC) is popularly used in many applications such as face recognition, and implemented in two steps: representation coding and classification. For a given set of testing images, SRC codes every image over the base images as a sparse representation then classifies it to the class with the least representation error. This scheme utilizes an individual representation rather than the collective one to classify such a set of images, doing so obviously ignores the correlation among the given images. In this paper, a joint representation classification (JRC) for collective face recognition is proposed. JRC takes the correlation of multiple images as well as a single representation into account. Under the assumption that the given face images are generally related to each other, JRC codes all the testing images over the base images simultaneously to facilitate recognition. To this end, the testing inputs are aligned into a matrix and the joint representation coding is formulated to a generalized $l_{2,q}-l_{2,p}$-minimization problem. To uniformly solve the induced optimization problems for any $q\in[1,2]$ and $p\in (0,2]$, an iterative quadratic method (IQM) is developed. IQM is proved to be a strict descent algorithm with convergence to the optimal solution. Moreover, a more practical IQM is proposed for large-scale case. Experimental results on three public databases show that the JRC with practical IQM no only saves much computational cost but also achieves better performance in collective face recognition than the state-of-the-arts.