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In optoacoustic tomography, image reconstruction is often performed with incomplete or noisy data, leading to reconstruction errors. Significant improvement in reconstruction accuracy may be achieved in such cases by using nonlinear…

Image and Video Processing · Electrical Eng. & Systems 2019-08-09 Shai Biton , Nadav Arbel , Gilad Drozdov , Guy Gilboa , Amir Rosenthal

Non-uniqueness and instability are characteristic features of image reconstruction processes. As a result, it is necessary to develop regularization methods that can be used to compute reliable approximate solutions. A regularization method…

Numerical Analysis · Mathematics 2022-12-16 Andrea Ebner , Markus Haltmeier

Recently, generative diffusion priors have made huge strides as inverse problem solvers, including the ability to be adapted for inference on out-of-distribution data. Concurrently, implicit neural representations (INRs) have emerged as…

Image and Video Processing · Electrical Eng. & Systems 2026-03-12 Maliha Hossain , Haley Duba-Sullivan , Amirkoushyar Ziabari

In recent literature there are plenty of works that combine handcrafted and learnable regularizers to solve inverse imaging problems. While this hybrid approach has demonstrated promising results, the motivation for combining handcrafted…

Computer Vision and Pattern Recognition · Computer Science 2025-05-23 Alexandros Gkillas , Dimitris Ampeliotis , Kostas Berberidis

The wavelet frame systems have been playing an active role in image restoration and many other image processing fields over the past decades, owing to the good capability of sparsely approximating piece-wise smooth functions such as images.…

Computer Vision and Pattern Recognition · Computer Science 2016-03-29 Liangtian He , Yilun Wang , Zhaoyin Xiang

Sparse hyperspectral unmixing from large spectral libraries has been considered to circumvent limitations of endmember extraction algorithms in many applications. This strategy often leads to ill-posed inverse problems, which can benefit…

Computer Vision and Pattern Recognition · Computer Science 2018-10-29 Ricardo Augusto Borsoi , Tales Imbiriba , José Carlos Moreira Bermudez , Cédric Richard

We propose an algorithm for rotational sparse coding along with an efficient implementation using steerability. Sparse coding (also called dictionary learning) is an important technique in image processing, useful in inverse problems,…

Image and Video Processing · Electrical Eng. & Systems 2020-01-31 Michael T. McCann , Vincent Andrearczyk , Michael Unser , Adrien Depeursinge

Variational methods for revealing visual concepts learned by convolutional neural networks have gained significant attention during the last years. Being based on noisy gradients obtained via back-propagation such methods require the…

Machine Learning · Computer Science 2018-05-02 Maximilian Baust , Florian Ludwig , Christian Rupprecht , Matthias Kohl , Stefan Braunewell

Learned sparse retrieval (LSR) is a family of neural methods that encode queries and documents into sparse lexical vectors that can be indexed and retrieved efficiently with an inverted index. We explore the application of LSR to the…

Information Retrieval · Computer Science 2024-02-28 Thong Nguyen , Mariya Hendriksen , Andrew Yates , Maarten de Rijke

We examine in this paper the problem of image registration from the new perspective where images are given by sparse approximations in parametric dictionaries of geometric functions. We propose a registration algorithm that looks for an…

Computer Vision and Pattern Recognition · Computer Science 2013-12-31 Alhussein Fawzi , Pascal Frossard

Many imaging technologies rely on tomographic reconstruction, which requires solving a multidimensional inverse problem given a finite number of projections. Backprojection is a popular class of algorithm for tomographic reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2020-06-03 Xueqing Liu , Paul Sajda

Dictionary learning is a cutting-edge area in imaging processing, that has recently led to state-of-the-art results in many signal processing tasks. The idea is to conduct a linear decomposition of a signal using a few atoms of a learned…

Machine Learning · Statistics 2016-05-26 Simeng Qu , Xiao Wang

Transformer architectures have achieved remarkable success across language, vision, and multimodal tasks, and there is growing demand for them to address in-context compositional learning tasks. In these tasks, models solve the target…

Machine Learning · Computer Science 2025-11-26 Wei Chen , Jingxi Yu , Zichen Miao , Qiang Qiu

This document contains an educational introduction to the problem of sparsifying parametric models with L0 regularization. We utilize this approach together with dictionary learning to learn sparse polynomial policies for deep reinforcement…

Machine Learning · Computer Science 2024-09-06 Nicolò Botteghi , Urban Fasel

The concept of sparsity has been extensively applied for regularization in image reconstruction. Typically, sparsifying transforms are either pre-trained on ground-truth images or adaptively trained during the reconstruction. Thereby,…

Image and Video Processing · Electrical Eng. & Systems 2022-03-07 Andreas Kofler , Christian Wald , Tobias Schaeffter , Markus Haltmeier , Christoph Kolbitsch

Ultrasound image reconstruction can be approximately cast as a linear inverse problem that has traditionally been solved with penalized optimization using the $l_1$ or $l_2$ norm, or wavelet-based terms. However, such regularization…

Computer Vision and Pattern Recognition · Computer Science 2023-08-01 Yuxin Zhang , Clément Huneau , Jérôme Idier , Diana Mateus

Discriminative features extracted from the sparse coding model have been shown to perform well for classification. Recent deep learning architectures have further improved reconstruction in inverse problems by considering new dense priors…

Information Theory · Computer Science 2026-03-27 Abiy Tasissa , Emmanouil Theodosis , Bahareh Tolooshams , Demba Ba

Various algorithms have been proposed for dictionary learning. Among those for image processing, many use image patches to form dictionaries. This paper focuses on whole-image recovery from corrupted linear measurements. We address the open…

Computer Vision and Pattern Recognition · Computer Science 2014-08-19 Yangyang Xu , Wotao Yin

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

We present a dictionary learning approach to compensate for the transformation of faces due to changes in view point, illumination, resolution, etc. The key idea of our approach is to force domain-invariant sparse coding, i.e., design a…

Computer Vision and Pattern Recognition · Computer Science 2015-09-15 Qiang Qiu , Rama Chellappa