Auto-Encoder based Structured Dictinoary Learning

Dictionary learning and deep learning are two popular representation learning paradigms, which can be combined to boost the classification task. However, existing combination methods often learn multiple dictionaries embedded in a cascade of layers, and a specialized classifier accordingly. This may inattentively lead to overfitting and high computational cost. In this paper, we present a novel deep auto-encoding architecture to learn only a dictionary for classification. To empower the dictionary with discrimination, we construct the dictionary with class-specific sub-dictionaries, and introduce supervision by imposing category constraints. The proposed framework is inspired by a sparse optimization method, namely Iterative Shrinkage Thresholding Algorithm, which characterizes the learning process by the forward-propagation based optimization w.r.t the dictionary only, reducing the number of parameters to learn and the computational cost dramatically. Extensive experiments demonstrate the effectiveness of our method in image classification.