Browsing by Author "Batard, Thomas"

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  • A class of nonlocal variational problems on a vector bundle for color image local contrast reduction/enhancement
    Bertalmío, Marcelo; Batard, Thomas (International Press of Boston, 2016)
    We extend two existing variational models from the Euclidean space to a vector bundle over a Riemannian manifold. The Euclidean models, dedicated to regularize or enhance some color image features, are based on the concept ...
  • A connection between image processing and artificial neural networks layers through a geometric model of visual perception
    Batard, Thomas; Maldonado, Eduard Ramon; Steidl, Gabriele; Bertalmío, Marcelo (Springer, 2019)
    In this paper, we establish a connection between image processing, visual perception, and deep learning by introducing a mathematical model inspired by visual perception from which neural network layers and image processing ...
  • A decomposition framework for image denoising algorithms
    Ghimpeteanu, Gabriela; Batard, Thomas; Bertalmío, Marcelo; Levine, Stacey (Institute of Electrical and Electronics Engineers (IEEE), 2016)
    In this paper, we consider an image decomposition model that provides a novel framework for image denoising. The model computes the components of the image to be processed in a moving frame that encodes its local geometry ...
  • A geometric model of brightness perception and its application to color images correction
    Batard, Thomas; Bertalmío, Marcelo (Springer, 2018)
    Human perception involves many features like contours, shapes, textures, and colors to name a few. Whereas several geometric models for contours, shapes and textures perception have been proposed, the geometry of color ...
  • A nonlocal variational formulation for the improvement of tone mapped images
    Cyriac, Praveen; Batard, Thomas; Bertalmío, Marcelo (SIAM (Society for Industrial and Applied Mathematics), 2014)
    Due to technical limitations, common display devices can only reproduce images having a low range of intensity values (dynamic range). As a consequence, the dynamic range of images encoding real world scenes, which is ...
  • Denoising an image by denoising its components in a moving frame
    Ghimpeteanu, Gabriela; Batard, Thomas; Bertalmío, Marcelo; Levine, Stacey (Springer, 2014)
    In this paper, we provide a new non-local method for image denoising. The key idea we develop is to denoise the components of the image in a well-chosen moving frame instead of the image itself.We prove the relevance of ...
  • Derivatives and inverse of cascaded linear + nonlinear neural models
    Martínez García, Marina; Cyriac, Praveen; Batard, Thomas; Bertalmío, Marcelo; Malo, Jesús (Public Library of Science (PLoS), 2018)
    In vision science, cascades of Linear+Nonlinear transforms are very successful in modeling a number of perceptual experiences. However, the conventional literature is usually too focused on only describing the forward ...
  • Duality principle for image regularization and perceptual color correction models
    Bertalmío, Marcelo; Batard, Thomas (Springer, 2015)
    In this paper, we show that the anisotropic nonlocal total variation involved in the image regularization model of Gilboa and Osher as well as in the perceptual color correction model of Bertalmío et al. possesses a dual ...
  • Generalized gradient on vector bundle – application to image denoising
    Batard, Thomas; Bertalmío, Marcelo (Springer, 2013)
    We introduce a gradient operator that generalizes the Euclidean and Riemannian gradients. This operator acts on sections of vector bundles and is determined by three geometric data: a Riemannian metric on the base manifold, ...
  • Harmonic flow for histogram matching
    Batard, Thomas; Bertalmío, Marcelo (Springer, 2014)
    We present a method to perform histogram matching be- tween two color images based on the concept of harmonic mapping be- tween Riemannian manifolds. The key idea is to associate the histogram of a color image to a Riemannian ...
  • Local denoising applied to RAW images may outperform non-local patch-based methods applied to the camera output
    Ghimpeteanu, Gabriela; Batard, Thomas; Seybold, Tamara; Bertalmío, Marcelo (The Society for Imaging Science and Technology (IS&T), 2016)
    State-of-the-art denoising methods achieve impressive results, even for large noise levels. However, they can not be implemented in camera hardware, mainly due to the fact that they are computationally too intensive. The ...
  • Local denoising based on curvature smoothing can visually outperform non-local methods on photographs with actual noise
    Ghimpeteanu, Gabriela; Kane, David; Batard, Thomas; Levine, Stacey; Bertalmío, Marcelo (Institute of Electrical and Electronics Engineers (IEEE), 2016)
    We propose a fast, local denoising method where the Euclidean curvature of the noisy image is approximated in a regularizing manner and a clean image is reconstructed from this smoothed curvature. User preference tests ...
  • On covariant derivatives and their applications to image regularization
    Batard, Thomas; Bertalmío, Marcelo (SIAM (Society for Industrial and Applied Mathematics), 2014)
    We present a generalization of the Euclidean and Riemannian gradient operators to a vector bundle, a geometric structure generalizing the concept of manifold. One of the key ideas is to replace the standard differentiation ...
  • Optimizing layout using spatial quality metrics and user preferences
    Bahrehmand, Arash; Batard, Thomas; Marques, Ricardo; Evans, Alun Thomas; Blat, Josep (Elsevier, 2017)
    Computational design is one of the most common tasks of immersive computer graphics projects, such as games, virtual reality and special effects. Layout planning is a challenging phase of architectural design, which requires ...
  • Several approaches to improve noise removal in photographic images
    Ghimpeteanu, Gabriela (Universitat Pompeu Fabra, 2018-01-23)
    Noise acquisition is an unavoidable component when capturing photographs, even in the case of current state of the art cameras. This problem is even accentuated when the lighting conditions are not ideal. Therefore, removing ...
  • A variational method for the optimization of tone mapping operators
    Cyriac, Praveen; Batard, Thomas; Bertalmío, Marcelo (Springer, 2014)
    Given any metric that compares images of di erent dynamic range, we propose a method to reduce their distance with respect to this metric. The key idea is to consider the metric as a non local operator. Then, we transform ...