SLRQA: A Sparse Low-Rank Quaternion Model for Color Image Processing with Convergence Analysis
摘要
In this paper, we propose a Sparse Low-rank Quaternion Approximation (SLRQA) model for color image processing problems with noisy observations. The proposed SLRQA is a quaternion model that combines low-rankness and sparsity priors without requiring an initial rank estimation. A proximal linearized ADMM (PL-ADMM) algorithm is proposed to solve SLRQA, and the global convergence is guaranteed under standard assumptions. When the observation is noise-free, a limiting case of the SLRQA, called SLRQA-NF, is proposed. Subsequently, a proximal linearized ADMM (PL-ADMM-NF) algorithm for SLRQA-NF is given. Since SLRQA-NF does not satisfy a widely-used assumption for the global convergence of ADMM-type algorithms, we propose a novel assumption under which the global convergence of PL-ADMM-NF is established. In numerical experiments, we verify the effectiveness of quaternion representation. Furthermore, for color image denoising and color image inpainting problems, SLRQA and SLRQA-NF demonstrate superior performance both quantitatively and visually when compared with some state-of-the-art methods.