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Author Francisco Javier Orozco; Ognjen Rudovic; Jordi Gonzalez; Maja Pantic edit   pdf
url  doi
openurl 
  Title Hierarchical On-line Appearance-Based Tracking for 3D Head Pose, Eyebrows, Lips, Eyelids and Irises Type Journal Article
  Year 2013 Publication (up) Image and Vision Computing Abbreviated Journal IMAVIS  
  Volume 31 Issue 4 Pages 322-340  
  Keywords On-line appearance models; Levenberg–Marquardt algorithm; Line-search optimization; 3D face tracking; Facial action tracking; Eyelid tracking; Iris tracking  
  Abstract In this paper, we propose an On-line Appearance-Based Tracker (OABT) for simultaneous tracking of 3D head pose, lips, eyebrows, eyelids and irises in monocular video sequences. In contrast to previously proposed tracking approaches, which deal with face and gaze tracking separately, our OABT can also be used for eyelid and iris tracking, as well as 3D head pose, lips and eyebrows facial actions tracking. Furthermore, our approach applies an on-line learning of changes in the appearance of the tracked target. Hence, the prior training of appearance models, which usually requires a large amount of labeled facial images, is avoided. Moreover, the proposed method is built upon a hierarchical combination of three OABTs, which are optimized using a Levenberg–Marquardt Algorithm (LMA) enhanced with line-search procedures. This, in turn, makes the proposed method robust to changes in lighting conditions, occlusions and translucent textures, as evidenced by our experiments. Finally, the proposed method achieves head and facial actions tracking in real-time.  
  Address  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language Summary Language Original Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes ISE; 605.203; 302.012; 302.018; 600.049 Approved no  
  Call Number ORG2013 Serial 2221  
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Author Ivan Huerta; Michael Holte; Thomas B. Moeslund; Jordi Gonzalez edit   pdf
doi  openurl
  Title Chromatic shadow detection and tracking for moving foreground segmentation Type Journal Article
  Year 2015 Publication (up) Image and Vision Computing Abbreviated Journal IMAVIS  
  Volume 41 Issue Pages 42-53  
  Keywords Detecting moving objects; Chromatic shadow detection; Temporal local gradient; Spatial and Temporal brightness and angle distortions; Shadow tracking  
  Abstract Advanced segmentation techniques in the surveillance domain deal with shadows to avoid distortions when detecting moving objects. Most approaches for shadow detection are still typically restricted to penumbra shadows and cannot cope well with umbra shadows. Consequently, umbra shadow regions are usually detected as part of moving objects, thus a ecting the performance of the nal detection. In this paper we address the detection of both penumbra and umbra shadow regions. First, a novel bottom-up approach is presented based on gradient and colour models, which successfully discriminates between chromatic moving cast shadow regions and those regions detected as moving objects. In essence, those regions corresponding to potential shadows are detected based on edge partitioning and colour statistics. Subsequently (i) temporal similarities between textures and (ii) spatial similarities between chrominance angle and brightness distortions are analysed for each potential shadow region for detecting the umbra shadow regions. Our second contribution re nes even further the segmentation results: a tracking-based top-down approach increases the performance of our bottom-up chromatic shadow detection algorithm by properly correcting non-detected shadows.
To do so, a combination of motion lters in a data association framework exploits the temporal consistency between objects and shadows to increase
the shadow detection rate. Experimental results exceed current state-of-the-
art in shadow accuracy for multiple well-known surveillance image databases which contain di erent shadowed materials and illumination conditions.
 
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  Area Expedition Conference  
  Notes ISE; 600.078; 600.063 Approved no  
  Call Number Admin @ si @ HHM2015 Serial 2703  
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Author Pau Rodriguez; Miguel Angel Bautista; Sergio Escalera; Jordi Gonzalez edit   pdf
url  doi
openurl 
  Title Beyond Oneshot Encoding: lower dimensional target embedding Type Journal Article
  Year 2018 Publication (up) Image and Vision Computing Abbreviated Journal IMAVIS  
  Volume 75 Issue Pages 21-31  
  Keywords Error correcting output codes; Output embeddings; Deep learning; Computer vision  
  Abstract Target encoding plays a central role when learning Convolutional Neural Networks. In this realm, one-hot encoding is the most prevalent strategy due to its simplicity. However, this so widespread encoding schema assumes a flat label space, thus ignoring rich relationships existing among labels that can be exploited during training. In large-scale datasets, data does not span the full label space, but instead lies in a low-dimensional output manifold. Following this observation, we embed the targets into a low-dimensional space, drastically improving convergence speed while preserving accuracy. Our contribution is two fold: (i) We show that random projections of the label space are a valid tool to find such lower dimensional embeddings, boosting dramatically convergence rates at zero computational cost; and (ii) we propose a normalized eigenrepresentation of the class manifold that encodes the targets with minimal information loss, improving the accuracy of random projections encoding while enjoying the same convergence rates. Experiments on CIFAR-100, CUB200-2011, Imagenet, and MIT Places demonstrate that the proposed approach drastically improves convergence speed while reaching very competitive accuracy rates.  
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  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes ISE; HuPBA; 600.098; 602.133; 602.121; 600.119 Approved no  
  Call Number Admin @ si @ RBE2018 Serial 3120  
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Author Ignasi Rius; Jordi Gonzalez; Mikhail Mozerov; Xavier Roca edit  openurl
  Title Automatic Learning of 3D Pose Variability in Walking Performances for Gait Analysis Type Journal
  Year 2008 Publication (up) International Journal for Computational Vision and Biomechanics Abbreviated Journal  
  Volume 1 Issue 1 Pages 33–43  
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  Notes ISE Approved no  
  Call Number ISE @ ise @ RGM2008 Serial 1020  
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Author Arjan Gijsenij; Theo Gevers; Joost Van de Weijer edit  doi
openurl 
  Title Generalized Gamut Mapping using Image Derivative Structures for Color Constancy Type Journal Article
  Year 2010 Publication (up) International Journal of Computer Vision Abbreviated Journal IJCV  
  Volume 86 Issue 2-3 Pages 127-139  
  Keywords  
  Abstract The gamut mapping algorithm is one of the most promising methods to achieve computational color constancy. However, so far, gamut mapping algorithms are restricted to the use of pixel values to estimate the illuminant. Therefore, in this paper, gamut mapping is extended to incorporate the statistical nature of images. It is analytically shown that the proposed gamut mapping framework is able to include any linear filter output. The main focus is on the local n-jet describing the derivative structure of an image. It is shown that derivatives have the advantage over pixel values to be invariant to disturbing effects (i.e. deviations of the diagonal model) such as saturated colors and diffuse light. Further, as the n-jet based gamut mapping has the ability to use more information than pixel values alone, the combination of these algorithms are more stable than the regular gamut mapping algorithm. Different methods of combining are proposed. Based on theoretical and experimental results conducted on large scale data sets of hyperspectral, laboratory and realworld scenes, it can be derived that (1) in case of deviations of the diagonal model, the derivative-based approach outperforms the pixel-based gamut mapping, (2) state-of-the-art algorithms are outperformed by the n-jet based gamut mapping, (3) the combination of the different n-jet based gamut  
  Address  
  Corporate Author Thesis  
  Publisher Kluwer Academic Publishers Hingham, MA, USA Place of Publication Editor  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0920-5691 ISBN Medium  
  Area Expedition Conference  
  Notes ISE Approved no  
  Call Number CAT @ cat @ GGW2010 Serial 1274  
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