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We consider the problem of estimating the inverse covariance matrix by maximizing the likelihood function with a penalty added to encourage the sparsity of the resulting matrix. We propose a new approach based on the split Bregman method to…

Machine Learning · Statistics 2015-03-17 Gui-Bo Ye , Jian-Feng Cai , Xiaohui Xie

Ultrasound computed tomography (USCT) holds great promise for breast cancer screening. Waveform inversion-based image reconstruction methods account for higher order diffraction effects and can produce high-resolution USCT images, but are…

Medical Physics · Physics 2017-08-25 Thomas P. Matthews , Kun Wang , Cuiping Li , Neb Duric , Mark A. Anastasio

We propose a variational regularization approach based on a multiscale representation called cylindrical shearlets aimed at dynamic imaging problems, especially dynamic tomography. The intuitive idea of our approach is to integrate a…

Numerical Analysis · Mathematics 2025-08-05 Tatiana A. Bubba , Tommi Heikkilä , Demetrio Labate , Luca Ratti

In this paper we investigate how standard nonlinear programming algorithms can be used to solve constrained optimization problems in a distributed manner. The optimization setup consists of a set of agents interacting through a…

Optimization and Control · Mathematics 2017-07-18 Ion Matei , John S. Baras

Problems in differentiable rendering often involve optimizing scene parameters that cause motion in image space. The gradients for such parameters tend to be sparse, leading to poor convergence. While existing methods address this sparsity…

Graphics · Computer Science 2025-03-31 Ishit Mehta , Manmohan Chandraker , Ravi Ramamoorthi

We consider the problem of minimizing the sum of an average function of a large number of smooth convex components and a general, possibly non-differentiable, convex function. Although many methods have been proposed to solve this problem…

Optimization and Control · Mathematics 2019-01-01 Le Thi Khanh Hien , Cuong V. Nguyen , Huan Xu , Canyi Lu , Jiashi Feng

In this paper, we consider a nonconvex optimization problem with nonlinear equality constraints. We assume that both, the objective function and the functional constraints are locally smooth. For solving this problem, we propose a…

Optimization and Control · Mathematics 2025-05-08 Lahcen El Bourkhissi , Ion Necoara

Bayesian image restoration has had a long history of successful application but one of the limitations that has prevented more widespread use is that the methods are generally computationally intensive. The authors recently addressed this…

Methodology · Statistics 2023-06-02 Karl Young , John Kornak , Eric Friedman

We study a class of optimization problems in which the objective function is given by the sum of a differentiable but possibly nonconvex component and a nondifferentiable convex regularization term. We introduce an auxiliary variable to…

Optimization and Control · Mathematics 2019-08-27 Neil K. Dhingra , Sei Zhen Khong , Mihailo R. Jovanović

This paper addresses a quadratic problem with assignment constraints, an NP-hard combinatorial optimization problem arisen from facility location, multiple-input multiple-output detection, and maximum mean discrepancy calculation et al. The…

Optimization and Control · Mathematics 2025-12-15 Lijun Xie , Ran Gu , Xin Liu

In image denoising problems, one widely-adopted approach is to minimize a regularized data-fit objective function, where the data-fit term is derived from a physical image acquisition model. Typically the regularizer is selected with two…

Optimization and Control · Mathematics 2015-08-13 Albert Oh , Rebecca Willett

Various problems in computer vision and medical imaging can be cast as inverse problems. A frequent method for solving inverse problems is the variational approach, which amounts to minimizing an energy composed of a data fidelity term and…

Computer Vision and Pattern Recognition · Computer Science 2020-06-17 Erich Kobler , Alexander Effland , Karl Kunisch , Thomas Pock

How to extract more and useful information for single image super resolution is an imperative and difficult problem. Learning-based method is a representative method for such task. However, the results are not so stable as there may exist…

Image and Video Processing · Electrical Eng. & Systems 2020-03-25 Hu Liang , Shengrong Zhao

We describe and examine an algorithm for tomographic image reconstruction where prior knowledge about the solution is available in the form of training images. We first construct a nonnegative dictionary based on prototype elements from the…

Computer Vision and Pattern Recognition · Computer Science 2015-08-18 Sara Soltani , Martin S. Andersen , Per Christian Hansen

This paper studies the matrix completion problem under arbitrary sampling schemes. We propose a new estimator incorporating both max-norm and nuclear-norm regularization, based on which we can conduct efficient low-rank matrix recovery…

Machine Learning · Statistics 2016-09-27 Ethan X. Fang , Han Liu , Kim-Chuan Toh , Wen-Xin Zhou

Motivated by re-weighted $\ell_1$ approaches for sparse recovery, we propose a lifted $\ell_1$ (LL1) regularization which is a generalized form of several popular regularizations in the literature. By exploring such connections, we discover…

Signal Processing · Electrical Eng. & Systems 2022-05-13 Yaghoub Rahimi , Sung Ha Kang , Yifei Lou

Image retargeting changes the aspect ratio of images while aiming to preserve content and minimise noticeable distortion. Fast and high-quality methods are particularly relevant at present, due to the large variety of image and display…

Computer Vision and Pattern Recognition · Computer Science 2022-03-28 Daniel Valdez-Balderas , Oleg Muraveynyk , Timothy Smith

The augmented Lagrangian (AL) method provides a flexible and efficient framework for solving extended-space full-waveform inversion (FWI), a constrained nonlinear optimization problem whereby we seek model parameters and wavefields that…

Geophysics · Physics 2021-06-29 Kamal Aghazade , Ali Gholami , Hossein S Aghamiry , Stephane Operto

We present a new vectorial total variation method that addresses the problem of color consistent image filtering. Our approach is inspired from the double-opponent cell representation in the human visual cortex. Existing methods of…

Computer Vision and Pattern Recognition · Computer Science 2016-05-20 Freddie Åström , Christoph Schnörr

We develop a second order primal-dual method for optimization problems in which the objective function is given by the sum of a strongly convex twice differentiable term and a possibly nondifferentiable convex regularizer. After introducing…

Optimization and Control · Mathematics 2020-08-31 Neil K. Dhingra , Sei Zhen Khong , Mihailo R. Jovanović