Tian Xin, Xie Kun, Zhang Hanling
IEEE Trans Image Process. 2022;31:4776-4789. doi: 10.1109/TIP.2022.3169694. Epub 2022 Jul 15.
Image restoration is a long-standing problem in signal processing and low-level computer vision. Previous studies have shown that imposing a low-rank Tucker decomposition (TKD) constraint could produce impressive performances. However, the TKD-based schemes may lead to the overfitting/underfitting problem because of incorrectly predefined ranks. To address this issue, we prove that the n -rank is upper bounded by the rank of each Tucker factor matrix. Using this relationship, we propose a formulation by imposing the nuclear norm regularization on the latent factors of TKD, which can avoid the burden of rank selection and reduce the computational cost when dealing with large-scale tensors. In this formulation, we adopt the Minimax Concave Penalty to remove the impulsive noise instead of the l -norm which may deviate from both the data-acquisition model and the prior model. Moreover, we employ an anisotropic total variation regularization to explore the piecewise smooth structure in both spatial and spectral domains. To solve this problem, we design the symmetric Gauss-Seidel (sGS) based alternating direction method of multipliers (ADMM) algorithm. Compared to the directly extended ADMM, our algorithm can achieve higher accuracy since more structural information is utilized. Finally, we conduct experiments on the three kinds of datasets, numerical results demonstrate the superiority of the proposed method, especially, the average PSNR of the proposed method can improve about 1~5dB for each noise level of color images.
图像恢复是信号处理和低级计算机视觉中的一个长期存在的问题。先前的研究表明,施加低秩塔克分解(TKD)约束可以产生令人印象深刻的性能。然而,基于TKD的方案可能会由于秩的预定义不正确而导致过拟合/欠拟合问题。为了解决这个问题,我们证明了n秩由每个塔克因子矩阵的秩上界。利用这种关系,我们提出了一种通过对TKD的潜在因子施加核范数正则化的公式,该公式可以避免秩选择的负担,并在处理大规模张量时降低计算成本。在这个公式中,我们采用最小最大凹惩罚来去除脉冲噪声,而不是可能偏离数据采集模型和先验模型的l范数。此外,我们采用各向异性全变差正则化来探索空间和光谱域中的分段光滑结构。为了解决这个问题,我们设计了基于对称高斯-赛德尔(sGS)的乘子交替方向法(ADMM)算法。与直接扩展的ADMM相比,我们的算法可以实现更高的精度,因为利用了更多的结构信息。最后,我们在三种数据集上进行了实验,数值结果证明了所提方法的优越性,特别是对于彩色图像的每个噪声水平,所提方法的平均峰值信噪比可以提高约1~5dB。