(Submitted on 14 Aug 2016)
Abstract: This paper proposes the Stacked Approximated Regression Machine (SARM), a novel, simple yet powerful deep learning (DL) baseline. We start by discussing the relationship between regularized regression models and feed-forward networks, with emphasis on the non-negative sparse coding and convolutional sparse coding models. We demonstrate how these models are naturally converted into a unified feed-forward network structure, which coincides with popular DL components. SARM is constructed by stacking multiple unfolded and truncated regression models. Compared to the PCANet, whose feature extraction layers are completely linear, SARM naturally introduces non-linearities, by embedding sparsity regularization. The parameters of SARM are easily obtained, by solving a series of light-weight problems, e.g., PCA or KSVD. Extensive experiments are conducted, which show that SARM outperforms the existing simple deep baseline, PCANet, and is on par with many state-of-the-art deep models, but with much lower computational loads.