Dr Kostas Papafitsoros
Lecturer in Mathematical Data Science
School of Mathematical Sciences
Queen Mary University of London
Research
Mathematical Imaging, Inverse Problems, Variational Regularisation Methods, Optimisation, Deep Learning, Environmental conservation
Interests
My main research area is mathematical imaging, in the interface of several areas of applied mathematics, like inverse problems, variational methods, calculus of variations, functional analysis, optimisation, optimal control, numerical analysis and deep learning. I have been particularly involved in the design, analysis and application of nonsmooth energy functionals incorporated in variational regularisation methods tailored for image processing. These functionals are at one hand discontinuity-preserving often stemming from their nonsmoothness, that is, they have the ability to preserve sharp edges in the images and on the other hand, they are adaptive to the specific structure of the given data. I am interested in combining these "classical" methods with modern data-driven and deep learning approaches.
I have a second research direction which is the result of my long-term involvement in environmental conservation with special focus on marine turtles, see the corresponding section of my personal website. I consider several applications of animal photo-identification (identification of individual animals via their unique morphological characteristics e.g. patterns/features), and in the same time consider various ways to enhance and automatise this process via modern imaging techniques. I am also looking at mathematical/statistical aspects of citizen science projects related to wildlife conservation.
Publications

Publications of specific relevance to the Centre for Probability, Statistics and Data Science
2024
Data‐driven methods for quantitative imagingDong G, Flaschel M, Hintermüller M,
Papafitsoros K, Sirotenko C and Tabelow K
Gamm-Mitteilungen,
Wiley 06-11-2024
A Descent Algorithm for the Optimal Control of ReLU Neural Network Informed PDEs Based on Approximate Directional DerivativesDong G, Hintermüller M and
Papafitsoros K Siam Journal on Optimization,
Society For Industrial & Applied Mathematics (Siam) vol. 34 (3), 2314-2349.
02-07-2024
WildlifeDatasets: An open-source toolkit for animal re-identificationČermák V, Adam L,
Papafitsoros K and Picek L
2024 IEEE/CVF Winter Conference on Applications of Computer Vision (WACV 2024).
01-02-2024
SeaTurtleID2022: A long-span dataset for reliable sea turtle re-identificationAdam L, Čermák V,
Papafitsoros K and Picek L
2024 IEEE/CVF Winter Conference on Applications of Computer Vision (WACV). vol. 00, 7131-7141.
08-01-20242023
Learning Regularization Parameter-Maps for Variational Image Reconstruction Using Deep Neural Networks and Algorithm UnrollingKofler A, Altekrüger F, Antarou Ba F, Kolbitsch C, Papoutsellis E, Schote D, Sirotenko C, Zimmermann FF and
Papafitsoros K Siam Journal on Imaging Sciences,
Society For Industrial & Applied Mathematics (Siam) vol. 16 (4), 2202-2246.
29-11-20232022
A social media-based framework for quantifying temporal changes to wildlife viewing intensityPapafitsoros K, Adam L and Schofield G
Ecological Modelling,
Elsevier vol. 476, 110223-110223.
29-11-2022
Bilevel Training Schemes in Imaging for Total Variation--Type Functionals with Convex IntegrandsPagliari V,
Papafitsoros K, Raib̧tă B and Vikelis A
Siam Journal on Imaging Sciences,
Society For Industrial and Applied Mathematics vol. 15 (4), 1690-1728.
10-10-2022
More aggressive sea turtles win fights over foraging resources independent of body size and years of presenceSchofield G,
Papafitsoros K, Chapman C, Shah A, Westover L, Dickson LCD and Katselidis KA
Animal Behaviour,
Elsevier vol. 190, 209-219.
01-08-2022
Dualization and Automatic Distributed Parameter Selection of Total Generalized Variation via Bilevel OptimizationHintermüller M,
Papafitsoros K, Rautenberg CN and Sun H
Numerical Functional Analysis and Optimization,
Taylor and Francis Group vol. 43 (8), 887-932.
05-05-2022
Photo-identification confirms polyandry in loggerhead sea turtlesPapafitsoros K, Dimitriadis C, Mazaris AD and Schofield G
Marine Ecology,
Wiley 19-01-2022
Optimization with learning-informed differential equation constraints and its applicationsDong G, Hintermüller M and
Papafitsoros K Esaim: Control, Optimisation and Calculus of Variations,
Edp Sciences vol. 28
11-01-20222020
Variable Step Mollifiers and ApplicationsHintermüller M,
Papafitsoros K and Rautenberg CN
Integral Equations and Operator Theory,
Springer vol. 92 (6)
30-11-2020
Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrateSchofield G
Animal Conservation 27-10-2020
Long‐term photo‐id and satellite tracking reveal sex‐biased survival linked to movements in an endangered speciesSchofield G, Klaassen M,
Papafitsoros K, Lilley MKS, Katselidis KA and Hays GC
Ecology,
Wiley vol. 101 (7)
30-03-2020
Patch-Wise Adaptive Weights Smoothing in RPolzehl J,
Papafitsoros K and Tabelow K
Journal of Statistical Software,
Foundation For Open Access Statistic vol. 95 (6)
01-01-20202019
Analysis and automatic parameter selection of a variational model for mixed Gaussian and salt-and-pepper noise removalCalatroni L and
Papafitsoros K Inverse Problems,
Iop Publishing vol. 35 (11)
23-09-2019
Chapter 11 Generating structured nonsmooth priors and associated primal-dual methodsHintermüller M and
Papafitsoros K In
Processing, Analyzing and Learning of Images, Shapes, and Forms: Part 2,
Elsevier 437-502.
01-01-2019
Quantitative Magnetic Resonance Imaging: From Fingerprinting to Integrated Physics-Based ModelsDong G, Hintermüller M and
Papafitsoros K Siam Journal on Imaging Sciences,
Society For Industrial & Applied Mathematics (Siam) vol. 12 (2), 927-971.
01-01-20192018
A function space framework for structural total variation regularization with applications in inverse problemsHintermüller M, Holler M and
Papafitsoros K Inverse Problems,
Iop Publishing vol. 34 (6)
27-04-2018
Complex movement patterns by foraging loggerhead sea turtles outside the breeding season identified using Argos-linked Fastloc-Global Positioning SystemDujon AM, Schofield G, Lester RE,
Papafitsoros K and Hays GC
Marine Ecology vol. 39 (1), e12489-e12489.
01-02-20182017
Analytical aspects of spatially adapted total variation regularisationHintermüller M,
Papafitsoros K and Rautenberg CN
Journal of Mathematical Analysis and Applications,
Elsevier vol. 454 (2), 891-935.
01-10-2017
Aerial and underwater surveys reveal temporal variation in cleaning-station use by sea turtles at a temperate breeding areaSchofield G,
Papafitsoros K, Haughey R and Katselidis K
Marine Ecology Progress Series vol. 575, 153-164.
20-07-20172016
Infimal Convolution Regularisation Functionals of BV and Lp SpacesBurger M,
Papafitsoros K, Papoutsellis E and Schönlieb C-B
Journal of Mathematical Imaging and Vision,
Springer Nature vol. 55 (3), 343-369.
03-02-2016
Infimal Convolution Regularisation Functionals of and Spaces. The CaseBurger M,
Papafitsoros K, Papoutsellis E and Schönlieb C-B
IFIP Advances in Information and Communication Technology. vol. 494, 169-179.
01-01-20162015
Asymptotic Behaviour of Total Generalised VariationPapafitsoros K and Valkonen T
Lecture Notes in Computer Science. vol. 9087, 702-714.
01-01-2015
A study of the one dimensional total generalised variation regularisation problemPapafitsoros K and Bredies K
Inverse Problems and Imaging,
American Institute of Mathematical Sciences (Aims) vol. 9 (2), 511-550.
01-01-2015
Analysis and Application of a Nonlocal HessianLellmann J,
Papafitsoros K, Schönlieb C and Spector D
Siam Journal on Imaging Sciences,
Society For Industrial & Applied Mathematics (Siam) vol. 8 (4), 2161-2202.
01-01-20152013
A Combined First and Second Order Variational Approach for Image ReconstructionPapafitsoros K and Schönlieb CB
Journal of Mathematical Imaging and Vision,
Springer Nature vol. 48 (2), 308-338.
10-05-20132012
Machine Learning for Quantitative Magnetic Resonance Image ReconstructionKofler A, Zimmermann FF and
Papafitsoros K In
Quantification of Biophysical Parameters in Medical Imaging,
Springer Nature 171-213.
24-02-2012