# Single Image Blind Deblurring Using Multi-Scale Latent Structure Prior

## TL;DR

This paper introduces a multi-scale latent structure prior for blind image deblurring, enabling efficient coarse-to-fine restoration of sharp images from blurry inputs, with theoretical support and competitive results.

## Contribution

The paper proposes a novel multi-scale latent structure prior for blind deblurring, incorporating a coarse-to-fine approach and efficient local self-example matching, kernel estimation, and deblurring.

## Key findings

- Achieves competitive deblurring results with faster speed.
- Validates the latent structure prior theoretically.
- Extends to non-uniform blind deblurring.

## Abstract

Blind image deblurring is a challenging problem in computer vision, which aims to restore both the blur kernel and the latent sharp image from only a blurry observation. Inspired by the prevalent self-example prior in image super-resolution, in this paper, we observe that a coarse enough image down-sampled from a blurry observation is approximately a low-resolution version of the latent sharp image. We prove this phenomenon theoretically and define the coarse enough image as a latent structure prior of the unknown sharp image. Starting from this prior, we propose to restore sharp images from the coarsest scale to the finest scale on a blurry image pyramid, and progressively update the prior image using the newly restored sharp image. These coarse-to-fine priors are referred to as \textit{Multi-Scale Latent Structures} (MSLS). Leveraging the MSLS prior, our algorithm comprises two phases: 1) we first preliminarily restore sharp images in the coarse scales; 2) we then apply a refinement process in the finest scale to obtain the final deblurred image. In each scale, to achieve lower computational complexity, we alternately perform a sharp image reconstruction with fast local self-example matching, an accelerated kernel estimation with error compensation, and a fast non-blind image deblurring, instead of computing any computationally expensive non-convex priors. We further extend the proposed algorithm to solve more challenging non-uniform blind image deblurring problem. Extensive experiments demonstrate that our algorithm achieves competitive results against the state-of-the-art methods with much faster running speed.