G-IK-SVD: parallel IK-SVD on GPUs for sparse representation of spatial big data

Sparse representation is a building block for many image processing applications such as compression, denoising, fusion and so on. In the era of “Big data”, the current spare representation methods generally do not meet the demand of time-efficiently processing the large image dataset. Aiming at this problem, this paper employed the contemporary general-purpose computing on the graphics processing unit (GPGPU) to extend a sparse representation method for big image datasets, IK-SVD, namely G-IK-SVD. The GPU-aided IK-SVD parallelized IK-SVD with three GPU optimization methods: (1) a batch-OMP algorithm based on GPU-aided Cholesky decomposition algorithm, (2) a GPU sparse matrix operation optimization method and (3) a hybrid parallel scheme. The experimental results indicate that (1) the GPU-aided batch-OMP algorithm shows speedups of up to 30 times than the sparse coding part of IK-SVD, (2) the optimized sparse matrix operations improve the whole procedure of IK-SVD up to 15 times,(3) the proposed parallel scheme can further accelerate the procedure of sparsely representing one large image dataset up to 24 times, and (4) G-IK-SVD can gain the same quality of dictionary learning as IK-SVD.