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This paper considers the constrained total variation (TV) denoising problem for complex-valued images. We extend the definition of TV seminorms for real-valued images to dealing with complex-valued ones. In particular, we introduce two…

Image and Video Processing · Electrical Eng. & Systems 2021-09-14 Yunhui Gao , Liangcai Cao

Image classifiers are known to be difficult to interpret and therefore require explanation methods to understand their decisions. We present ShearletX, a novel mask explanation method for image classifiers based on the shearlet transform --…

Computer Vision and Pattern Recognition · Computer Science 2023-05-01 Stefan Kolek , Robert Windesheim , Hector Andrade Loarca , Gitta Kutyniok , Ron Levie

Multi-energy computed tomography (CT) with photon counting detectors (PCDs) enables spectral imaging as PCDs can assign the incoming photons to specific energy channels. However, PCDs with many spectral channels drastically increase the…

Image and Video Processing · Electrical Eng. & Systems 2022-11-03 Satu I. Inkinen , Mikael A. K. Brix , Miika T. Nieminen , Simon Arridge , Andreas Hauptmann

A major challenge in X-ray computed tomography (CT) is reducing radiation dose while maintaining high quality of reconstructed images. To reduce the radiation dose, one can reduce the number of projection views (sparse-view CT); however, it…

Machine Learning · Statistics 2019-09-17 Xuehang Zheng , Il Yong Chun , Zhipeng Li , Yong Long , Jeffrey A. Fessler

Computed tomography (CT) has been developed as a non-destructive technique for observing minute internal images of samples. It has been difficult to obtain photo-realistic (clean or clear) CT images due to various unwanted artifacts…

Quantum Physics · Physics 2023-09-12 Kyungtaek Jun

Although larger datasets are crucial for training large deep models, the rapid growth of dataset size has brought a significant challenge in terms of considerable training costs, which even results in prohibitive computational expenses.…

Computer Vision and Pattern Recognition · Computer Science 2025-08-06 Sheng-Feng Yu , Jia-Jiun Yao , Wei-Chen Chiu

In this paper, we investigate image reconstruction for dynamic Computed Tomography. The motion of the target with respect to the measurement acquisition rate leads to highly resolved in time but highly undersampled in space measurements.…

Image and Video Processing · Electrical Eng. & Systems 2025-06-27 Pablo Arratia , Matthias Ehrhardt , Lisa Kreusser

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

Kidney DCE-MRI aims at both qualitative assessment of kidney anatomy and quantitative assessment of kidney function by estimating the tracer kinetic (TK) model parameters. Accurate estimation of TK model parameters requires an accurate…

Machine Learning · Computer Science 2022-01-03 Aziz Koçanaoğulları , Cemre Ariyurek , Onur Afacan , Sila Kurugol

Image reconstruction in X-ray transmission tomography has been an important research field for decades. In light of data volume increasing faster than processor speeds, one needs accelerated iterative algorithms to solve the optimization…

Optimization and Control · Mathematics 2016-10-28 Soysal Degirmenci , Joseph A. O'Sullivan , David G. Politte

Although quantization has emerged as a promising approach to reducing computational complexity across various high-level vision tasks, it inevitably leads to accuracy loss in image super-resolution (SR) networks. This is due to the…

Computer Vision and Pattern Recognition · Computer Science 2024-07-19 Cheeun Hong , Kyoung Mu Lee

Bilinear pooling of Convolutional Neural Network (CNN) features [22, 23], and their compact variants [10], have been shown to be effective at fine-grained recognition, scene categorization, texture recognition, and visual question-answering…

Computer Vision and Pattern Recognition · Computer Science 2017-07-24 Tsung-Yu Lin , Subhransu Maji

The unrolling method has been investigated for learning variational models in X-ray computed tomography. However, it has been observed that directly unrolling the regularization model through gradient descent does not produce satisfactory…

Image and Video Processing · Electrical Eng. & Systems 2024-04-19 Yijie Yang , Qifeng Gao , Yuping Duan

Image segmentation is to extract meaningful objects from a given image. For degraded images due to occlusions, obscurities or noises, the accuracy of the segmentation result can be severely affected. To alleviate this problem, prior…

Computer Vision and Pattern Recognition · Computer Science 2021-04-01 Daoping Zhang , Lok Ming Lui

The skull segmentation from CT scans can be seen as an already solved problem. However, in MR this task has a significantly greater complexity due to the presence of soft tissues rather than bones. Capturing the bone structures from MR…

Image and Video Processing · Electrical Eng. & Systems 2024-10-18 Kamil Kwarciak , Mateusz Daniol , Daria Hemmerling , Marek Wodzinski

Numerous diffusion model (DM)-based methods have been proposed for solving inverse imaging problems. Among these, a recent line of work has demonstrated strong performance by formulating sampling as an optimization procedure that enforces…

Image and Video Processing · Electrical Eng. & Systems 2025-11-19 Shijun Liang , Ismail Alkhouri , Qing Qu , Rongrong Wang , Saiprasad Ravishankar

One of the fundamental assumptions of compressive sensing (CS) is that a signal can be reconstructed from a small number of samples by solving an optimization problem with the appropriate regularization term. Two standard regularization…

Image and Video Processing · Electrical Eng. & Systems 2019-06-26 Elin Farnell , Henry Kvinge , Julia R. Dupuis , Michael Kirby , Chris Peterson , Elizabeth C. Schundler

We propose a new constrained optimization approach to hyperspectral (HS) image restoration. Most existing methods restore a desirable HS image by solving some optimization problem, which consists of a regularization term(s) and a…

Signal Processing · Electrical Eng. & Systems 2020-09-09 Saori Takeyama , Shunsuke Ono , Itsuo Kumazawa

The use of ray projections to reconstruct images is a common technique in medical imaging. Dealing with incomplete data is particularly important when a patient is vulnerable to potentially damaging radiation or is unable to cope with the…

Neural and Evolutionary Computing · Computer Science 2024-06-04 Mohammad Majid al-Rifaie , Tim Blackwell

Feature selection identifies subsets of informative features and reduces dimensions in the original feature space, helping provide insights into data generation or a variety of domain problems. Existing methods mainly depend on feature…

Machine Learning · Computer Science 2021-06-07 Xinxing Wu , Qiang Cheng