BSIK-SVD: A dictionary-learning algorithm for block-sparse representations

Sparse dictionary learning has attracted enormous interest in image processing and data representation in recent years. To improve the performance of dictionary learning, we propose an efficient block-structured incoherent K-SVD algorithm for the sparse representation of signals. Without relying on any prior knowledge of the group structure for the input data, we develop a two-stage agglomerative hierarchical clustering method for block sparse representations. This clustering method adaptively identifies the underlying block structure of the dictionary under the restricted conditions of both a maximal block size and a minimal distance between the blocks. Furthermore, to meet the constraints of both the upper bound and the lower bound of the mutual coherence of dictionary atoms, we introduce a regularization term for the objective function to suppress the block coherence of the overcomplete dictionary. The experiments on synthetic data and real images demonstrate that the proposed algorithm has lower representation error, higher visual quality and better reconstructed results than other state-of-the-art methods.