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Bilevel learning is a powerful optimization technique that has extensively been employed in recent years to bridge the world of model-driven variational approaches with data-driven methods. Upon suitable parametrization of the desired…

Spectral Computed Tomography (CT) is an emerging technology that enables to estimate the concentration of basis materials within a scanned object by exploiting different photon energy spectra. In this work, we aim at efficiently solving a…

Optimization and Control · Mathematics 2021-03-26 Alessandro Perelli , Martin S. Andersen

We investigate efficient algorithmic realisations for robust deconvolution of grey-value images with known space-invariant point-spread function, with emphasis on 1D motion blur scenarios. The goal is to make deconvolution suitable as…

Computer Vision and Pattern Recognition · Computer Science 2017-09-22 Martin Welk , Patrik Raudaschl , Thomas Schwarzbauer , Martin Erler , Martin Läuter

This paper presents an error analysis of classical and learned Tikhonov regularization schemes for inverse problems. We first demonstrate, both theoretically and numerically, that using a fixed regularization parameter across varying noise…

Numerical Analysis · Mathematics 2026-04-02 Arne Behrens , Meira Iske , Ming Jiang , Peter Maass , Sebastian Neumayer

This paper proposes a novel approach to regularize the ill-posed blind image deconvolution (blind image deblurring) problem using deep generative networks. We employ two separate deep generative models - one trained to produce sharp images…

Computer Vision and Pattern Recognition · Computer Science 2019-08-21 Muhammad Asim , Fahad Shamshad , Ali Ahmed

Group sparsity has shown great potential in various low-level vision tasks (e.g, image denoising, deblurring and inpainting). In this paper, we propose a new prior model for image denoising via group sparsity residual constraint (GSRC). To…

Computer Vision and Pattern Recognition · Computer Science 2017-03-06 Zhiyuan Zha , Xin Liu , Ziheng Zhou , Xiaohua Huang , Jingang Shi , Zhenhong Shang , Lan Tang , Yechao Bai , Qiong Wang , Xinggan Zhang

We consider an unsupervised bilevel optimization strategy for learning regularization parameters in the context of imaging inverse problems in the presence of additive white Gaussian noise. Compared to supervised and semi-supervised metrics…

Optimization and Control · Mathematics 2024-03-13 Carlo Santambrogio , Monica Pragliola , Alessandro Lanza , Marco Donatelli , Luca Calatroni

Image deblurring task is an ill-posed one, where exists infinite feasible solutions for blurry image. Modern deep learning approaches usually discard the learning of blur kernels and directly employ end-to-end supervised learning. Popular…

Computer Vision and Pattern Recognition · Computer Science 2022-08-30 Sidun Liu , Peng Qiao , Yong Dou

In this work, we propose Regularization-by-Equivariance (REV), a novel structure-adaptive regularization scheme for solving imaging inverse problems under incomplete measurements. This regularization scheme utilizes the equivariant…

Optimization and Control · Mathematics 2022-02-15 Junqi Tang

We propose a very fast and effective one-step restoring method for blurry face images. In the last decades, many blind deblurring algorithms have been proposed to restore latent sharp images. However, these algorithms run slowly because of…

Computer Vision and Pattern Recognition · Computer Science 2017-11-28 Lingxiao Wang , Yali Li , Shengjin Wang

We consider the problem of fusing an arbitrary number of multiband, i.e., panchromatic, multispectral, or hyperspectral, images belonging to the same scene. We use the well-known forward observation and linear mixture models with Gaussian…

Computer Vision and Pattern Recognition · Computer Science 2018-07-19 Reza Arablouei

Depth from defocus and defocus deblurring from a single image are two challenging problems that are derived from the finite depth of field in conventional cameras. Coded aperture imaging is one of the techniques that is used for improving…

Computer Vision and Pattern Recognition · Computer Science 2016-03-15 Mina Masoudifar , Hamid Reza Pourreza

We consider the problem of reconstructing the cross--power spectrum of an unobservable multivariate stochatic process from indirect measurements of a second multivariate stochastic process, related to the first one through a linear…

Numerical Analysis · Mathematics 2020-04-22 Elisabetta Vallarino , Sara Sommariva , Michele Piana , Alberto Sorrentino

Regularization plays a crucial role in reliably utilizing imaging systems for scientific and medical investigations. It helps to stabilize the process of computationally undoing any degradation caused by physical limitations of the imaging…

Image and Video Processing · Electrical Eng. & Systems 2021-05-26 Manu Ghulyani , Deepak G Skariah , Muthuvel Arigovindan

We propose a simple method for estimating noise level from a single color image. In most image-denoising algorithms, an accurate noise-level estimate results in good denoising performance; however, it is difficult to estimate noise level…

Computer Vision and Pattern Recognition · Computer Science 2019-04-05 Akihiro Nakamura , Michihiro Kobayashi

In this work we introduce a new method that combines Parallel MRI and Compressed Sensing (CS) for accelerated image reconstruction from subsampled k-space data. The method first computes a convolved image, which gives the convolution…

Medical Physics · Physics 2021-09-20 Efrat Shimron , Andrew G. Webb , Haim Azhari

In this paper, a new regularization term is proposed to solve mathematical image problems. By using difference operators in the four directions; horizontal, vertical and two diagonal directions, an estimation of derivative amplitude is…

Numerical Analysis · Mathematics 2022-09-14 Alireza Hosseini

A main drawback of classical Tikhonov regularization is that often the parameters required to apply theoretical results, e.g., the smoothness of the sought-after solution and the noise level, are unknown in practice. In this paper we…

Numerical Analysis · Mathematics 2021-01-01 Daniel Gerth , Ronny Ramlau

Algorithms for automatically selecting a scalar or locally varying regularization parameter for total variation models with an $L^{\tau}$-data fidelity term, $\tau\in \{1,2\}$, are presented. The automated selection of the regularization…

Numerical Analysis · Mathematics 2017-01-02 Andreas Langer

Modern digital cameras rely on the sequential execution of separate image processing steps to produce realistic images. The first two steps are usually related to denoising and demosaicking where the former aims to reduce noise from the…

Computer Vision and Pattern Recognition · Computer Science 2019-04-02 Filippos Kokkinos , Stamatios Lefkimmiatis