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Author Jordi Roca; C. Alejandro Parraga; Maria Vanrell edit   pdf
doi  openurl
  Title Chromatic settings and the structural color constancy index Type Journal Article
  Year 2013 Publication Journal of Vision Abbreviated Journal JV  
  Volume (down) 13 Issue 4-3 Pages 1-26  
  Keywords  
  Abstract Color constancy is usually measured by achromatic setting, asymmetric matching, or color naming paradigms, whose results are interpreted in terms of indexes and models that arguably do not capture the full complexity of the phenomenon. Here we propose a new paradigm, chromatic setting, which allows a more comprehensive characterization of color constancy through the measurement of multiple points in color space under immersive adaptation. We demonstrated its feasibility by assessing the consistency of subjects' responses over time. The paradigm was applied to two-dimensional (2-D) Mondrian stimuli under three different illuminants, and the results were used to fit a set of linear color constancy models. The use of multiple colors improved the precision of more complex linear models compared to the popular diagonal model computed from gray. Our results show that a diagonal plus translation matrix that models mechanisms other than cone gain might be best suited to explain the phenomenon. Additionally, we calculated a number of color constancy indices for several points in color space, and our results suggest that interrelations among colors are not as uniform as previously believed. To account for this variability, we developed a new structural color constancy index that takes into account the magnitude and orientation of the chromatic shift in addition to the interrelations among colors and memory effects.  
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  Notes CIC; 600.052; 600.051; 605.203 Approved no  
  Call Number Admin @ si @ RPV2013 Serial 2288  
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Author Javier Vazquez; J. Kevin O'Regan; Maria Vanrell; Graham D. Finlayson edit  url
doi  openurl
  Title A new spectrally sharpened basis to predict colour naming, unique hues, and hue cancellation Type Journal Article
  Year 2012 Publication Journal of Vision Abbreviated Journal VSS  
  Volume (down) 12 Issue 6 (7) Pages 1-14  
  Keywords  
  Abstract When light is reflected off a surface, there is a linear relation between the three human photoreceptor responses to the incoming light and the three photoreceptor responses to the reflected light. Different colored surfaces have different linear relations. Recently, Philipona and O'Regan (2006) showed that when this relation is singular in a mathematical sense, then the surface is perceived as having a highly nameable color. Furthermore, white light reflected by that surface is perceived as corresponding precisely to one of the four psychophysically measured unique hues. However, Philipona and O'Regan's approach seems unrelated to classical psychophysical models of color constancy. In this paper we make this link. We begin by transforming cone sensors to spectrally sharpened counterparts. In sharp color space, illumination change can be modeled by simple von Kries type scalings of response values within each of the spectrally sharpened response channels. In this space, Philipona and O'Regan's linear relation is captured by a simple Land-type color designator defined by dividing reflected light by incident light. This link between Philipona and O'Regan's theory and Land's notion of color designator gives the model biological plausibility. We then show that Philipona and O'Regan's singular surfaces are surfaces which are very close to activating only one or only two of such newly defined spectrally sharpened sensors, instead of the usual three. Closeness to zero is quantified in a new simplified measure of singularity which is also shown to relate to the chromaticness of colors. As in Philipona and O'Regan's original work, our new theory accounts for a large variety of psychophysical color data.  
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  Notes CIC Approved no  
  Call Number Admin @ si @ VOV2012 Serial 1998  
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Author C. Alejandro Parraga; Jordi Roca; Maria Vanrell edit  url
doi  openurl
  Title Do Basic Colors Influence Chromatic Adaptation? Type Journal Article
  Year 2011 Publication Journal of Vision Abbreviated Journal VSS  
  Volume (down) 11 Issue 11 Pages 85  
  Keywords  
  Abstract Color constancy (the ability to perceive colors relatively stable under different illuminants) is the result of several mechanisms spread across different neural levels and responding to several visual scene cues. It is usually measured by estimating the perceived color of a grey patch under an illuminant change. In this work, we hypothesize whether chromatic adaptation (without a reference white or grey) could be driven by certain colors, specifically those corresponding to the universal color terms proposed by Berlin and Kay (1969). To this end we have developed a new psychophysical paradigm in which subjects adjust the color of a test patch (in CIELab space) to match their memory of the best example of a given color chosen from the universal terms list (grey, red, green, blue, yellow, purple, pink, orange and brown). The test patch is embedded inside a Mondrian image and presented on a calibrated CRT screen inside a dark cabin. All subjects were trained to “recall” their most exemplary colors reliably from memory and asked to always produce the same basic colors when required under several adaptation conditions. These include achromatic and colored Mondrian backgrounds, under a simulated D65 illuminant and several colored illuminants. A set of basic colors were measured for each subject under neutral conditions (achromatic background and D65 illuminant) and used as “reference” for the rest of the experiment. The colors adjusted by the subjects in each adaptation condition were compared to the reference colors under the corresponding illuminant and a “constancy index” was obtained for each of them. Our results show that for some colors the constancy index was better than for grey. The set of best adapted colors in each condition were common to a majority of subjects and were dependent on the chromaticity of the illuminant and the chromatic background considered.  
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  Series Volume Series Issue Edition  
  ISSN 1534-7362 ISBN Medium  
  Area Expedition Conference  
  Notes CIC Approved no  
  Call Number Admin @ si @ PRV2011 Serial 1759  
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Author Xavier Otazu; C. Alejandro Parraga; Maria Vanrell edit  url
doi  openurl
  Title Towards a unified chromatic inducction model Type Journal Article
  Year 2010 Publication Journal of Vision Abbreviated Journal VSS  
  Volume (down) 10 Issue 12:5 Pages 1-24  
  Keywords Visual system; Color induction; Wavelet transform  
  Abstract In a previous work (X. Otazu, M. Vanrell, & C. A. Párraga, 2008b), we showed how several brightness induction effects can be predicted using a simple multiresolution wavelet model (BIWaM). Here we present a new model for chromatic induction processes (termed Chromatic Induction Wavelet Model or CIWaM), which is also implemented on a multiresolution framework and based on similar assumptions related to the spatial frequency and the contrast surround energy of the stimulus. The CIWaM can be interpreted as a very simple extension of the BIWaM to the chromatic channels, which in our case are defined in the MacLeod-Boynton (lsY) color space. This new model allows us to unify both chromatic assimilation and chromatic contrast effects in a single mathematical formulation. The predictions of the CIWaM were tested by means of several color and brightness induction experiments, which showed an acceptable agreement between model predictions and psychophysical data.  
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  Notes CIC Approved no  
  Call Number CAT @ cat @ OPV2010 Serial 1450  
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Author Maria Vanrell; Jordi Vitria; Xavier Roca edit  openurl
  Title A multidimensional scaling approach to explore the behavior of a texture perception algorithm. Type Journal Article
  Year 1997 Publication Machine Vision and Applications Abbreviated Journal  
  Volume (down) 9 Issue Pages 262–271  
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  Notes OR;ISE;CIC;MV Approved no  
  Call Number BCNPCL @ bcnpcl @ VVR1997 Serial 35  
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Author Felipe Lumbreras; Ramon Baldrich; Maria Vanrell; Joan Serrat; Juan J. Villanueva edit  openurl
  Title Multiresolution colour texture representations for tile classification Type Miscellaneous
  Year 1999 Publication Proceedings of the VIII Symposium Nacional de Reconocimiento de Formas y Analisis de Imagenes Abbreviated Journal  
  Volume (down) Issue Pages  
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  Abstract  
  Address Bilbao  
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  Notes ADAS;CIC Approved no  
  Call Number ADAS @ adas @ LBV1999a Serial 3  
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Author Xavier Roca; Jordi Vitria; Maria Vanrell; Juan J. Villanueva edit  openurl
  Title Visual behaviours for binocular navigation with autonomous systems. Type Miscellaneous
  Year 1999 Publication Proceedings of the VIII Symposium Nacional de Reconocimiento de Formas y Analisis de Imagenes Abbreviated Journal  
  Volume (down) Issue Pages  
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  Abstract  
  Address Bilbao  
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  Area Expedition Conference  
  Notes OR;ISE;CIC;MV Approved no  
  Call Number BCNPCL @ bcnpcl @ RVV1999a Serial 13  
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Author Xavier Roca; Jordi Vitria; Maria Vanrell; Juan J. Villanueva edit  openurl
  Title Gaze control in a binocular robot systems Type Miscellaneous
  Year 1999 Publication Abbreviated Journal  
  Volume (down) Issue Pages  
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  Abstract  
  Address Barcelona  
  Corporate Author Thesis  
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  Area Expedition Conference  
  Notes OR;ISE;CIC;MV Approved no  
  Call Number BCNPCL @ bcnpcl @ RVV1999b Serial 41  
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Author Felipe Lumbreras; Ramon Baldrich; Maria Vanrell; Joan Serrat; Juan J. Villanueva edit  openurl
  Title Multiresolution texture classification of ceramic tiles. Type Book Chapter
  Year 1999 Publication Recent Research developments in optical engineering, Research Signpost, 2: 213–228 Abbreviated Journal  
  Volume (down) Issue Pages  
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  Abstract  
  Address India  
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  Notes ADAS;CIC Approved no  
  Call Number ADAS @ adas @ LBV1999b Serial 45  
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Author Robert Benavente; M.C. Olive; Maria Vanrell; Ramon Baldrich edit  openurl
  Title Colour Perception: A Simple Method for Colour Naming. Type Miscellaneous
  Year 1999 Publication Abbreviated Journal  
  Volume (down) Issue Pages  
  Keywords  
  Abstract  
  Address Girona  
  Corporate Author Thesis  
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  Notes CIC Approved no  
  Call Number CAT @ cat @ BOV1999 Serial 47  
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Author Robert Benavente; Maria Vanrell edit  openurl
  Title A colour naming experiment Type Report
  Year 2001 Publication CVC Technical Report #56 Abbreviated Journal  
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  Address CVC (UAB)  
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  Notes CIC Approved no  
  Call Number CAT @ cat @ BeV2001 Serial 78  
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Author Felipe Lumbreras; Joan Serrat; Ramon Baldrich; Maria Vanrell; Juan J. Villanueva edit  openurl
  Title Color Texture Recognition Through Multiresolution Features Type Miscellaneous
  Year 2001 Publication QCAV 2001 International Conference on Quality Control by Artificial Vision, France, 1:114–121. Abbreviated Journal  
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  Notes ADAS;CIC Approved no  
  Call Number ADAS @ adas @ LSB2001 Serial 124  
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Author Maria Vanrell; Jordi Vitria; Xavier Roca edit  openurl
  Title A General Morphological Framework for Perceptual Texture Discrimination based on Granulometries. Type Miscellaneous
  Year 1993 Publication Technical Workshop on Mathematical Morphology and its Applications to Signal Processing. Abbreviated Journal  
  Volume (down) Issue Pages  
  Keywords  
  Abstract  
  Address Barcelona  
  Corporate Author Thesis  
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  Area Expedition Conference  
  Notes OR;ISE;CIC;MV Approved no  
  Call Number BCNPCL @ bcnpcl @ VVR1993 Serial 154  
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Author Maria Vanrell; Felipe Lumbreras; A. Pujol; Ramon Baldrich; Josep Llados; Juan J. Villanueva edit  openurl
  Title Colour Normalisation Based on Background Information. Type Miscellaneous
  Year 2001 Publication Proceeding ICIP 2001, IEEE International Conference on Image Processing Abbreviated Journal ICIP 2001  
  Volume (down) Issue 1 Pages 874–877  
  Keywords  
  Abstract  
  Address Grecia.  
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  Area Expedition Conference  
  Notes ADAS;DAG;CIC Approved no  
  Call Number ADAS @ adas @ VLP2001 Serial 167  
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