A sparse reconstruction based algorithm for image and video classification

The success of sparse reconstruction based classification algorithms largely depends on the choice of overcomplete bases (dictionary). Existing methods either use the training samples as the dictionary elements or learn a dictionary by optimizing a cost function with an additional discriminating component. While the former method requires a good number of training samples per class and is not suitable for video signals, the later adds instability and more computational load. This paper presents a sparse reconstruction based classification algorithm that mitigates the above difficulties. We argue that learning class-specific dictionaries, one per class, is a natural approach to discrimination. We describe each training signal by an error vector consisting of the reconstruction errors the signal produces w.r.t each dictionary. This representation is robust to noise, occlusion and is also highly discriminative. The efficacy of the proposed method is demonstrated in terms of high accuracy for image-based Species and Face recognition and video-based Action recognition.