Labmat: Learned Feature-Domain Block Matching For Image Restoration

Grouping of similar patches, called block matching, has been widely used in image restoration applications. Popular block matching algorithms exploit image non-local similarities in spatial or a fixed transform domain, e.g., wavelets and DCT. However, applying these methods on corrupted patches usually leads to degraded matching accuracy, thus limiting the image restoration performance. In this work, we develop a novel methodology for performing block matching in a supervised way by learning multi-layer sparsifying transforms. The proposed learned transform-domain block matching method for image restoration, dubbed LABMAT, is shown to have better accuracy in terms of clustering similar blocks in the presence of noise, and it also achieves an improved denoising performance when it is incorporated into popular non-local denoising schemes.