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Author A. Diplaros; N. Vlassis; Theo Gevers edit  openurl
  Title A Spatially Constrained Generative Model and an EM Algorithm for Image Segmentation Type Journal
  Year 2007 Publication IEEE Transactions on Neural Networks Abbreviated Journal  
  Volume 18 Issue 3 Pages (down) 798-808  
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  Notes ISE Approved no  
  Call Number Admin @ si @ DVG2007 Serial 947  
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Author Ivan Huerta; Marco Pedersoli; Jordi Gonzalez; Alberto Sanfeliu edit  doi
openurl 
  Title Combining where and what in change detection for unsupervised foreground learning in surveillance Type Journal Article
  Year 2015 Publication Pattern Recognition Abbreviated Journal PR  
  Volume 48 Issue 3 Pages (down) 709-719  
  Keywords Object detection; Unsupervised learning; Motion segmentation; Latent variables; Support vector machine; Multiple appearance models; Video surveillance  
  Abstract Change detection is the most important task for video surveillance analytics such as foreground and anomaly detection. Current foreground detectors learn models from annotated images since the goal is to generate a robust foreground model able to detect changes in all possible scenarios. Unfortunately, manual labelling is very expensive. Most advanced supervised learning techniques based on generic object detection datasets currently exhibit very poor performance when applied to surveillance datasets because of the unconstrained nature of such environments in terms of types and appearances of objects. In this paper, we take advantage of change detection for training multiple foreground detectors in an unsupervised manner. We use statistical learning techniques which exploit the use of latent parameters for selecting the best foreground model parameters for a given scenario. In essence, the main novelty of our proposed approach is to combine the where (motion segmentation) and what (learning procedure) in change detection in an unsupervised way for improving the specificity and generalization power of foreground detectors at the same time. We propose a framework based on latent support vector machines that, given a noisy initialization based on motion cues, learns the correct position, aspect ratio, and appearance of all moving objects in a particular scene. Specificity is achieved by learning the particular change detections of a given scenario, and generalization is guaranteed since our method can be applied to any possible scene and foreground object, as demonstrated in the experimental results outperforming the state-of-the-art.  
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  Notes ISE; 600.063; 600.078 Approved no  
  Call Number Admin @ si @ HPG2015 Serial 2589  
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Author Arjan Gijsenij; R. Lu; Theo Gevers; De Xu edit  doi
openurl 
  Title Color Constancy for Multiple Light Source Type Journal Article
  Year 2012 Publication IEEE Transactions on Image Processing Abbreviated Journal TIP  
  Volume 21 Issue 2 Pages (down) 697-707  
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  Abstract Impact factor 2010: 2.92
Impact factor 2011/2012?: 3.32
Color constancy algorithms are generally based on the simplifying assumption that the spectral distribution of a light source is uniform across scenes. However, in reality, this assumption is often violated due to the presence of multiple light sources. In this paper, we will address more realistic scenarios where the uniform light-source assumption is too restrictive. First, a methodology is proposed to extend existing algorithms by applying color constancy locally to image patches, rather than globally to the entire image. After local (patch-based) illuminant estimation, these estimates are combined into more robust estimations, and a local correction is applied based on a modified diagonal model. Quantitative and qualitative experiments on spectral and real images show that the proposed methodology reduces the influence of two light sources simultaneously present in one scene. If the chromatic difference between these two illuminants is more than 1° , the proposed framework outperforms algorithms based on the uniform light-source assumption (with error-reduction up to approximately 30%). Otherwise, when the chromatic difference is less than 1° and the scene can be considered to contain one (approximately) uniform light source, the performance of the proposed method framework is similar to global color constancy methods.
 
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  Series Volume Series Issue Edition  
  ISSN 1057-7149 ISBN Medium  
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  Notes ALTRES;ISE Approved no  
  Call Number Admin @ si @ GLG2012a Serial 1852  
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Author Arjan Gijsenji; Theo Gevers edit  doi
openurl 
  Title Color Constancy Using Natural Image Statistics and Scene Semantics Type Journal Article
  Year 2011 Publication IEEE Transactions on Pattern Analysis and Machine Intelligence Abbreviated Journal TPAMI  
  Volume 33 Issue 4 Pages (down) 687-698  
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  Abstract Existing color constancy methods are all based on specific assumptions such as the spatial and spectral characteristics of images. As a consequence, no algorithm can be considered as universal. However, with the large variety of available methods, the question is how to select the method that performs best for a specific image. To achieve selection and combining of color constancy algorithms, in this paper natural image statistics are used to identify the most important characteristics of color images. Then, based on these image characteristics, the proper color constancy algorithm (or best combination of algorithms) is selected for a specific image. To capture the image characteristics, the Weibull parameterization (e.g., grain size and contrast) is used. It is shown that the Weibull parameterization is related to the image attributes to which the used color constancy methods are sensitive. An MoG-classifier is used to learn the correlation and weighting between the Weibull-parameters and the image attributes (number of edges, amount of texture, and SNR). The output of the classifier is the selection of the best performing color constancy method for a certain image. Experimental results show a large improvement over state-of-the-art single algorithms. On a data set consisting of more than 11,000 images, an increase in color constancy performance up to 20 percent (median angular error) can be obtained compared to the best-performing single algorithm. Further, it is shown that for certain scene categories, one specific color constancy algorithm can be used instead of the classifier considering several algorithms.  
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  ISSN 0162-8828 ISBN Medium  
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  Notes ISE Approved no  
  Call Number Admin @ si @ GiG2011 Serial 1724  
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Author Eduard Vazquez; Theo Gevers; M. Lucassen; Joost Van de Weijer; Ramon Baldrich edit  doi
openurl 
  Title Saliency of Color Image Derivatives: A Comparison between Computational Models and Human Perception Type Journal Article
  Year 2010 Publication Journal of the Optical Society of America A Abbreviated Journal JOSA A  
  Volume 27 Issue 3 Pages (down) 613–621  
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  Abstract In this paper, computational methods are proposed to compute color edge saliency based on the information content of color edges. The computational methods are evaluated on bottom-up saliency in a psychophysical experiment, and on a more complex task of salient object detection in real-world images. The psychophysical experiment demonstrates the relevance of using information theory as a saliency processing model and that the proposed methods are significantly better in predicting color saliency (with a human-method correspondence up to 74.75% and an observer agreement of 86.8%) than state-of-the-art models. Furthermore, results from salient object detection confirm that an early fusion of color and contrast provide accurate performance to compute visual saliency with a hit rate up to 95.2%.  
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  Notes ISE;CIC Approved no  
  Call Number CAT @ cat @ VGL2010 Serial 1275  
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