Locally regularized Anchored Neighborhood Regression for fast Super-Resolution

The goal of learning-based image Super-Resolution (SR) is to generate a plausible and visually pleasing High-Resolution (HR) image from a given Low-Resolution (LR) input. The problem is dramatically under-constrained, which relies on examples or some strong image priors to better reconstruct the missing HR image details. This paper addresses the problem of learning the mapping functions (i.e. projection matrices) between the LR and HR images based on a dictionary of LR and HR examples. One recently proposed method, Anchored Neighborhood Regression (ANR) [1], provides state-of-the-art quality performance and is very fast. In this paper, we propose an improved variant of ANR, namely Locally regularized Anchored Neighborhood Regression (LANR), which utilizes the locality-constrained regression in place of the ridge regression in ANR. LANR assigns different freedom for each neighbor dictionary atom according to its correlation to the input LR patch, thus the learned projection matrices are much more flexible. Experimental results demonstrate that the proposed algorithm performs efficiently and effectively over state-of-the-art methods, e.g., 0.1-0.4 dB in term of PSNR better than ANR.