Search Results for author: Ozan Öktem

Found 27 papers, 15 papers with code

Reconstruction for Sparse View Tomography of Long Objects Applied to Imaging in the Wood Industry

no code implementations5 Mar 2024 Buda Bajić, Johannes A. J. Huber, Benedikt Neyses, Linus Olofsson, Ozan Öktem

In the wood industry, logs are commonly quality screened by discrete X-ray scans on a moving conveyor belt from a few source positions.

Riemannian geometry for efficient analysis of protein dynamics data

1 code implementation15 Aug 2023 Willem Diepeveen, Carlos Esteve-Yagüe, Jan Lellmann, Ozan Öktem, Carola-Bibiane Schönlieb

First, it comes with a rich structure to account for a wide range of geometries that can be modelled after an energy landscape.

Neural incomplete factorization: learning preconditioners for the conjugate gradient method

no code implementations25 May 2023 Paul Häusner, Ozan Öktem, Jens Sjölund

Finding suitable preconditioners to accelerate iterative solution methods, such as the conjugate gradient method, is an active area of research.

Computational Efficiency

Calibrating Ensembles for Scalable Uncertainty Quantification in Deep Learning-based Medical Segmentation

no code implementations20 Sep 2022 Thomas Buddenkotte, Lorena Escudero Sanchez, Mireia Crispin-Ortuzar, Ramona Woitek, Cathal McCague, James D. Brenton, Ozan Öktem, Evis Sala, Leonardo Rundo

On the contrary, we propose a scalable and intuitive framework to calibrate ensembles of deep learning models to produce uncertainty quantification measurements that approximate the classification probability.

Active Learning Uncertainty Quantification

Spectral decomposition of atomic structures in heterogeneous cryo-EM

1 code implementation12 Sep 2022 Carlos Esteve-Yagüe, Willem Diepeveen, Ozan Öktem, Carola-Bibiane Schönlieb

The dataset contains noisy tomographic projections of the electrostatic potential of the macromolecule, taken from different viewing directions, and in the heterogeneous case, each image corresponds to a different conformation of the macromolecule.

Deep Learning for Material Decomposition in Photon-Counting CT

no code implementations5 Aug 2022 Alma Eguizabal, Ozan Öktem, Mats U. Persson

In this work, we present a novel deep-learning solution for material decomposition in PCCT, based on an unrolled/unfolded iterative network.

Image Reconstruction

3D helical CT Reconstruction with a Memory Efficient Learned Primal-Dual Architecture

no code implementations24 May 2022 Jevgenija Rudzusika, Buda Bajić, Thomas Koehler, Ozan Öktem

To the best of our knowledge, this work is the first to apply an unrolled deep learning architecture for reconstruction on full-sized clinical data, like those in the Low dose CT image and projection data set (LDCT).

Computed Tomography (CT)

Deep learning based dictionary learning and tomographic image reconstruction

no code implementations26 Aug 2021 Jevgenija Rudzusika, Thomas Koehler, Ozan Öktem

This work presents an approach for image reconstruction in clinical low-dose tomography that combines principles from sparse signal processing with ideas from deep learning.

Computed Tomography (CT) Decoder +3

Deep Microlocal Reconstruction for Limited-Angle Tomography

no code implementations12 Aug 2021 Héctor Andrade-Loarca, Gitta Kutyniok, Ozan Öktem, Philipp Petersen

We present a deep learning-based algorithm to jointly solve a reconstruction problem and a wavefront set extraction problem in tomographic imaging.

Adversarially learned iterative reconstruction for imaging inverse problems

1 code implementation30 Mar 2021 Subhadip Mukherjee, Ozan Öktem, Carola-Bibiane Schönlieb

In numerous practical applications, especially in medical image reconstruction, it is often infeasible to obtain a large ensemble of ground-truth/measurement pairs for supervised learning.

Image Reconstruction

Learned convex regularizers for inverse problems

1 code implementation6 Aug 2020 Subhadip Mukherjee, Sören Dittmer, Zakhar Shumaylov, Sebastian Lunz, Ozan Öktem, Carola-Bibiane Schönlieb

We consider the variational reconstruction framework for inverse problems and propose to learn a data-adaptive input-convex neural network (ICNN) as the regularization functional.

Computed Tomography (CT) Deblurring

Spatiotemporal PET reconstruction using ML-EM with learned diffeomorphic deformation

no code implementations26 Aug 2019 Ozan Öktem, Camille Pouchol, Olivier Verdier

We expect this approach to scale very well to higher resolutions and to 3D, as the overall cost of our algorithm is only marginally greater than that of a standard ML-EM algorithm.

Multi-Scale Learned Iterative Reconstruction

1 code implementation1 Aug 2019 Andreas Hauptmann, Jonas Adler, Simon Arridge, Ozan Öktem

Applicability of these methods to large scale inverse problems is however limited by the available memory for training and extensive training times, the latter due to computationally expensive forward models.

Computed Tomography (CT)

Extraction of digital wavefront sets using applied harmonic analysis and deep neural networks

1 code implementation5 Jan 2019 Héctor Andrade-Loarca, Gitta Kutyniok, Ozan Öktem, Philipp Petersen

Microlocal analysis provides deep insight into singularity structures and is often crucial for solving inverse problems, predominately, in imaging sciences.

A New Variational Model for Joint Image Reconstruction and Motion Estimation in Spatiotemporal Imaging

no code implementations9 Dec 2018 Chong Chen, Barbara Gris, Ozan Öktem

This model consists of two components, one for conducting modified static image reconstruction, and the other performs sequentially indirect image registration.

Image Reconstruction Image Registration +2

Deep Bayesian Inversion

1 code implementation14 Nov 2018 Jonas Adler, Ozan Öktem

Characterizing statistical properties of solutions of inverse problems is essential for decision making.

Decision Making Image Reconstruction

Task adapted reconstruction for inverse problems

no code implementations27 Aug 2018 Jonas Adler, Sebastian Lunz, Olivier Verdier, Carola-Bibiane Schönlieb, Ozan Öktem

The paper considers the problem of performing a task defined on a model parameter that is only observed indirectly through noisy data in an ill-posed inverse problem.

Image Reconstruction

Data-driven nonsmooth optimization

1 code implementation2 Aug 2018 Sebastian Banert, Axel Ringh, Jonas Adler, Johan Karlsson, Ozan Öktem

In this work, we consider methods for solving large-scale optimization problems with a possibly nonsmooth objective function.

Optimization and Control 90C25 (Primary) 68T05, 47H05 (Secondary)

Adversarial Regularizers in Inverse Problems

2 code implementations NeurIPS 2018 Sebastian Lunz, Ozan Öktem, Carola-Bibiane Schönlieb

Inverse Problems in medical imaging and computer vision are traditionally solved using purely model-based methods.

Denoising

Learning to solve inverse problems using Wasserstein loss

1 code implementation30 Oct 2017 Jonas Adler, Axel Ringh, Ozan Öktem, Johan Karlsson

We propose using the Wasserstein loss for training in inverse problems.

Learned Primal-dual Reconstruction

4 code implementations20 Jul 2017 Jonas Adler, Ozan Öktem

We propose the Learned Primal-Dual algorithm for tomographic reconstruction.

Rolling Shutter Correction SSIM

Indirect Image Registration with Large Diffeomorphic Deformations

3 code implementations13 Jun 2017 Chong Chen, Ozan Öktem

The paper adapts the large deformation diffeomorphic metric mapping framework for image registration to the indirect setting where a template is registered against a target that is given through indirect noisy observations.

Image Registration

Solving ill-posed inverse problems using iterative deep neural networks

5 code implementations13 Apr 2017 Jonas Adler, Ozan Öktem

We propose a partially learned approach for the solution of ill posed inverse problems with not necessarily linear forward operators.

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