|Higher-Order Total Directional Variation. European Congress of Mathematics, Portorož, SI, 2021. (Type: Conference | | )|
In this talk we discuss a new higher-order and anisotropic total variation model for image processing. This new model combines higher-order total variation regularisation with possibly inhomogeneous, smooth elliptic anisotropies.
We prove some properties of this total variation model and of the associated spaces of tensors with finite variations. We show the existence of solutions to a related regularity-fidelity optimization problem and prove a decomposition formula which we will use to develop a primal-dual hybrid gradient approach for its numerical approximation.
This choice of total variation regularisation allows to preserve and enhance intrinsic anisotropic features in images. We illustrate this on various examples from different imaging applications: image denoising, wavelet-based image zooming, and reconstruction of surfaces from scattered height measurements.
|Variational Osmosis for image fusion in Cultural Heritage. SIAM IS20, Toronto, CA (online), 2020. (Type: Conference | | )|
We propose a new variational model for nonlinear image fusion. Our approach incorporates the osmosis model proposed in Vogel et al. (2013) and Weickert et al. (2013) as an energy term in a variational model. The osmosis energy is known to realize visually plausible image data fusion, invariant to multiplicative brightness changes. On the practical side, our model requires minimal supervision and parameter tuning and can encode prior information on the structure of the images to be fused. We develop a primal-dual algorithm for solving this new image fusion model and we apply the resulting minimisation scheme to multi-modal image fusion for face fusion, colour transfer and some cultural heritage conservation challenges. Visual comparison to state-of-the-art proves the quality and flexibility of our method.
|Anisotropic osmosis filter for shadow removal in images. ICIAM 2019, Valencia, 2019. (Type: Conference | | )|
Mini-symposium: "Anisotropic variational models and partial differential equations"
organized by Bertram Düring (University of Sussex), Carola-Bibiane Schönlieb (University of Cambridge)
We present an anisotropic extension of the isotropic osmosis model introduced by Weickert et al. (2013) for visual computing applications. Our model minimises an energy which involves a suitable quadratic form where the local directionality of the imaging structure is considered. Our anisotropic approach applied to shadow removal applications outperforms the isotropic one since it does not suffer from blurring artefacts at the shadow boundaries.
|Total Directional Variation for Video Denoising. 7th Scale Space and Variational Methods, Hofgeismar, 2019. (Type: Conference | )|
|Unveiling the invisible: a mathematical touch to challenges in CH. Do Not Touch? 3D in Museums, Cambridge, 2019. (Type: Conference | )|
|Mathematical osmosis imaging for multi-modal, multi-spectral applications in Cultural Heritage. IP4AI, Ghent, 2018. (Type: Conference | )|
|Higher-order Total directional Variation with Imaging Applications. SIAM IS, Bologna, 2018. (Type: Conference | | )|
This presentation is part of Minisymposium “MS26 – New trends in inpainting”
organized by: Yann Gousseau (Telecom ParisTech) , Simon Masnou (Université Lyon 1) .
The talk will be devoted to a new class of higher-order anisotropic total variation regularizers, with applications to image denoising and to digital elevation maps reconstruction. Our model can mix isotropic and anisotropic regularization at various derivative orders, which helps recovering the intrinsic structure of images and surfaces. I will describe a primal-dual approach for the numerical implementation of the model. The talk will be illustrated with various numerical examples.
|Generalized Image Osmosis Filtering with shadow removal imaging applications. SIAM IS, Bologna, 2018. (Type: Conference | | )|
This presentation is part of Minisymposium “MS15 – Nonlinear Diffusion: Models, Extensions and Algorithms (2 parts)”
organized by: Ke Chen (University of Liverpool) , Joachim Weickert (Saarland University) , Xue-Cheng Tai (Hong Kong Baptist University) .
We introduce a generalized image osmosis model, enhancing the quality of the reconstructed image in the shadow removal problem by means of directional diffusion weights. Analogies with the second order linear and nonlinear diffusion inpainting equations (e.g. Harmonic, AMLE, Total Variation) acting on the shadow boundaries are further shown. Numerical details of efficient implementations for the model are provided, as well as applications to real images and to cultural heritage conservation challenges.
|Commonware Roman Pottery from excavation to digital features classification. VMV – INI, Cambridge, 2017. (Type: Conference | | )|
Joint presentation with Dr Alessandro Launaro (Faculty of Classics, University of Cambridge)
Session Title: Challenges from End-Users
Event: [OFBW33] Mathematics of Imaging and Vision
Part of the programme "Variational methods and effective algorithms for imaging and vision", Isaac Newton Institute, Cambridge
Ancient pots are generally classified by shape, represented as a profile (section): similar profiles are assumed to be related (e.g. functionally, if not chronologically). Commonware pottery is the most widely found class of material culture at Roman sites, yet its enormous range of shapes is such that its classification is at least 10-20 times more laborious than other classes (fineware, amphorae). However, important development in the field of computer-aided image analysis might provide archaeologists with a set of automated form recognition tools to help them during their classification process.
|Anisotropic Surface Inpainting for Digital Elevation Maps. 1st Joint Meeting Brazil-Italy in Mathematics, Rio De Janeiro, 2016. (Type: Conference | | )|
Mini-symposium: 20- Variational Methods and PDE in Imaging
Organizers: A. Leaci (University of Salento), E. Teixeira (Federal University of Ceará)
|Anisotropic Surface Inpainting for Digital Elevation Maps. British Applied Mathematical Colloquium 2016, Oxford, 2016. (Type: Conference | | )|
Mini-symposium: "Next Generation Mathematical Approaches in Inverse Imaging"
organized by Daniel Lesnic (University of Leeds), Carola-Bibiane Schönlieb (University of Cambridge), Manuchehr Soleimani (University of Bath)
SEMINARS, PUBLIC EVENTS and OUTREACH
|Inverse Problems in Cultural Heritage. Veronesi Tutti Math Webinar Series, 14.04.2021. (Type: Presentation | | )|
In this talk we describe two challenges tackled by the “Mathematics for Applications in Cultural Heritage” (MACH) research group in Cambridge, UK. The stated aim of the group is to support art and humanities scholars in their research, with innovative solutions of interest for STEM disciplines. In the first part, we will show a carousel of mathematical imaging approaches for the virtual restoration of damages in medieval illuminated manuscripts. We will explore the suitability of local, nonlocal and deep-learning inpainting methods in real-world scenario, in collaboration with the Fitzwilliam Museum (University of Cambridge, UK). In the second part, we will detail about an unsupervised workflow for clustering Roman commonware potsherds, which are frequently found at different excavation sites. By bringing an alternative order to the existing archaeological corpora, archaeologists will gain new knowledge on the shape production in the Central Tyrrenean area during the Roman Age. This work is done in collaboration with the Faculty of Classics (University of Cambridge, UK).
|Unveiling the invisible: From thermal analysis on frescoes to virtual restoration of manuscripts. Hercules Lab, Évora, 07.02.2020. (Type: Presentation | | )|
part of the "Erasmus Mundus Joint Master in Archaeological Materials Science Seminar" – series 2018-2020
|Panel Discussion – Gesamtkunstwerk: ART, ARCHITECTURE & AI. Emmanuel College, Cambridge, 01.03.2017. (Type: Presentation | | )|
MTArt is organising a talk at CAMBRIDGE UNIVERSITY on the 1st March 2017 on ART, ARCHITECTURE and AI revisiting the idea of ‘The TOTAL WORK OF ART’ (GESAMTKUNSTWERK). The panel will concentrate on the CIVIC ROLE OF ART, dividing between DIGITAL (through the exploration of AI) and the PHYSICAL (through ARCHITECTURE).
|Variational Methods in Image Processing. University of Verona, 16.12.2016. (Type: Presentation | )|
|Introduzione al calcolo parallelo per il metodo degli elementi finiti. University of Verona, 24.04.2013. (Type: Presentation | )|