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Author Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Mutiresolution Wavelet Framework Reproduces Induction Effects Type Journal
Year 2007 Publication Perception 36:167–167, supp Abbreviated Journal  
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Notes CIC Approved no  
Call Number CAT @ cat @ OVP2007 Serial 842  
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Author C. Alejandro Parraga; Robert Benavente; Maria Vanrell edit  openurl
Title Modeling Colour-Naming Space with Fuzzy Sets Type Journal
Year 2007 Publication Perception 36:198–198, supp Abbreviated Journal  
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Area Expedition Conference  
Notes CIC Approved no  
Call Number CAT @ cat @ PBV2007 Serial 843  
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Author Robert Benavente; Maria Vanrell edit  openurl
Title Parametrizacion del Espacio de Categorias de Color Type Miscellaneous
Year 2007 Publication Proceedings del VIII Congreso Nacional del Color Abbreviated Journal  
Volume Issue Pages 77–78  
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Address Madrid (Spain)  
Corporate Author Thesis  
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Series Editor Series Title Abbreviated Series Title (up)  
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ISSN ISBN Medium  
Area Expedition Conference CNC’07  
Notes CAT;CIC Approved no  
Call Number CAT @ cat @ BeV2007 Serial 905  
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Author Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Multiresolution Wavelet Framework Models Brightness Induction Effects Type Journal
Year 2008 Publication Vision Research Abbreviated Journal VR  
Volume 48 Issue 5 Pages 733–751  
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Notes CIC Approved no  
Call Number CAT @ cat @ OVP2008a Serial 927  
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Author Javier Vazquez; Maria Vanrell; Ramon Baldrich edit  openurl
Title Towards a Psychophysical Evaluation of Colour Constancy Algorithms Type Conference Article
Year 2008 Publication 4th European Conference on Colour in Graphics, Imaging and Vision Proceedings Abbreviated Journal  
Volume Issue Pages 372–377  
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Address Terrassa (Spain)  
Corporate Author Thesis  
Publisher Place of Publication Editor  
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Series Editor Series Title Abbreviated Series Title (up)  
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ISSN ISBN Medium  
Area Expedition Conference CGIV08  
Notes CAT;CIC Approved no  
Call Number CAT @ cat @ VVB2008a Serial 968  
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Author C. Alejandro Parraga; Robert Benavente; Maria Vanrell; Ramon Baldrich edit  openurl
Title Modelling Inter-Colour Regions of Colour Naming Space Type Conference Article
Year 2008 Publication 4th European Conference on Colour in Graphics, Imaging and Vision Proceedings Abbreviated Journal  
Volume Issue Pages 218–222  
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Address Terrassa (Spain)  
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Publisher Place of Publication Editor  
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Series Editor Series Title Abbreviated Series Title (up)  
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ISSN ISBN Medium  
Area Expedition Conference CGIV08  
Notes CAT;CIC Approved no  
Call Number CAT @ cat @ PBV2008 Serial 969  
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Author Robert Benavente; Maria Vanrell; Ramon Baldrich edit  openurl
Title Parametric Fuzzy Sets for Automatic Color Naming Type Journal
Year 2008 Publication Journal of the Optical Society of America A Abbreviated Journal  
Volume 25 Issue 10 Pages 2582–2593  
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Notes CIC Approved no  
Call Number CAT @ cat @ BVB2008 Serial 1004  
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Author Eduard Vazquez; Maria Vanrell edit  openurl
Title Eines per al desenvolupament de competencies de enginyeria en un assignatura de Intel·ligencia Artificial Type Miscellaneous
Year 2008 Publication V Jornades d’Innovacio Docent (UAB) Abbreviated Journal  
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Address Bellaterra (Spain)  
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Series Editor Series Title Abbreviated Series Title (up)  
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Area Expedition Conference  
Notes CIC Approved no  
Call Number CAT @ cat @ VaV2008 Serial 1011  
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Author Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Colour induction effects are modelled by a low-level multiresolution wavelet framework Type Journal
Year 2008 Publication Perception 37(Suppl.): 107 Abbreviated Journal  
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Series Editor Series Title Abbreviated Series Title (up)  
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Area Expedition Conference  
Notes CIC Approved no  
Call Number CAT @ cat @ OVP2008b Serial 1055  
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Author C. Alejandro Parraga; Robert Benavente; Maria Vanrell; Ramon Baldrich edit  url
openurl 
Title Psychophysical measurements to model inter-colour regions of colour-naming space Type Journal Article
Year 2009 Publication Journal of Imaging Science and Technology Abbreviated Journal  
Volume 53 Issue 3 Pages 031106 (8 pages)  
Keywords image processing; Analysis  
Abstract JCR Impact Factor 2009: 0.391
In this paper, we present a fuzzy-set of parametric functions which segment the CIE lab space into eleven regions which correspond to the group of common universal categories present in all evolved languages as identified by anthropologists and linguists. The set of functions is intended to model a color-name assignment task by humans and differs from other models in its emphasis on the inter-color boundary regions, which were explicitly measured by means of a psychophysics experiment. In our particular implementation, the CIE lab space was segmented into eleven color categories using a Triple Sigmoid as the fuzzy sets basis, whose parameters are included in this paper. The model’s parameters were adjusted according to the psychophysical results of a yes/no discrimination paradigm where observers had to choose (English) names for isoluminant colors belonging to regions in-between neighboring categories. These colors were presented on a calibrated CRT monitor (14-bit x 3 precision). The experimental results show that inter- color boundary regions are much less defined than expected and color samples other than those near the most representatives are needed to define the position and shape of boundaries between categories. The extended set of model parameters is given as a table.		  
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Notes CIC Approved no  
Call Number CAT @ cat @ PBV2009 Serial 1157  
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Author Javier Vazquez; C. Alejandro Parraga; Maria Vanrell; Ramon Baldrich edit  doi
openurl 
Title Color Constancy Algorithms: Psychophysical Evaluation on a New Dataset Type Journal Article
Year 2009 Publication Journal of Imaging Science and Technology Abbreviated Journal  
Volume 53 Issue 3 Pages 031105–9  
Keywords  
Abstract The estimation of the illuminant of a scene from a digital image has been the goal of a large amount of research in computer vision. Color constancy algorithms have dealt with this problem by defining different heuristics to select a unique solution from within the feasible set. The performance of these algorithms has shown that there is still a long way to go to globally solve this problem as a preliminary step in computer vision. In general, performance evaluation has been done by comparing the angular error between the estimated chromaticity and the chromaticity of a canonical illuminant, which is highly dependent on the image dataset. Recently, some workers have used high-level constraints to estimate illuminants; in this case selection is based on increasing the performance on the subsequent steps of the systems. In this paper we propose a new performance measure, the perceptual angular error. It evaluates the performance of a color constancy algorithm according to the perceptual preferences of humans, or naturalness (instead of the actual optimal solution) and is independent of the visual task. We show the results of a new psychophysical experiment comparing solutions from three different color constancy algorithms. Our results show that in more than a half of the judgments the preferred solution is not the one closest to the optimal solution. Our experiments were performed on a new dataset of images acquired with a calibrated camera with an attached neutral grey sphere, which better copes with the illuminant variations of the scene.  
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Notes CIC Approved no  
Call Number CAT @ cat @ VPV2009a Serial 1171  
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Author Javier Vazquez; C. Alejandro Parraga; Maria Vanrell edit  openurl
Title Ordinal pairwise method for natural images comparison Type Journal Article
Year 2009 Publication Perception Abbreviated Journal PER  
Volume 38 Issue Pages 180  
Keywords  
Abstract 38(Suppl.)ECVP Abstract Supplement
We developed a new psychophysical method to compare different colour appearance models when applied to natural scenes. The method was as follows: two images (processed by different algorithms) were displayed on a CRT monitor and observers were asked to select the most natural of them. The original images were gathered by means of a calibrated trichromatic digital camera and presented one on top of the other on a calibrated screen. The selection was made by pressing on a 6-button IR box, which allowed observers to consider not only the most natural but to rate their selection. The rating system allowed observers to register how much more natural was their chosen image (eg, much more, definitely more, slightly more), which gave us valuable extra information on the selection process. The results were analysed considering both the selection as a binary choice (using Thurstone's law of comparative judgement) and using Bradley-Terry method for ordinal comparison. Our results show a significant difference in the rating scales obtained. Although this method has been used in colour constancy algorithm comparisons, its uses are much wider, eg to compare algorithms of image compression, rendering, recolouring, etc.		  
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Notes CIC Approved no  
Call Number CAT @ cat @ VPV2009b Serial 1191  
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Author Robert Benavente; C. Alejandro Parraga; Maria Vanrell edit  openurl
Title Colour categories boundaries are better defined in contextual conditions Type Journal Article
Year 2009 Publication Perception Abbreviated Journal PER  
Volume 38 Issue Pages 36  
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Abstract In a previous experiment [Parraga et al, 2009 Journal of Imaging Science and Technology 53(3)] the boundaries between basic colour categories were measured by asking subjects to categorize colour samples presented in isolation (ie on a dark background) using a YES/NO paradigm. Results showed that some boundaries (eg green – blue) were very diffuse and the subjects' answers presented bimodal distributions, which were attributed to the emergence of non-basic categories in those regions (eg turquoise). To confirm these results we performed a new experiment focussed on the boundaries where bimodal distributions were more evident. In this new experiment rectangular colour samples were presented surrounded by random colour patches to simulate contextual conditions on a calibrated CRT monitor. The names of two neighbouring colours were shown at the bottom of the screen and subjects selected the boundary between these colours by controlling the chromaticity of the central patch, sliding it across these categories' frontier. Results show that in this new experimental paradigm, the formerly uncertain inter-colour category boundaries are better defined and the dispersions (ie the bimodal distributions) that occurred in the previous experiment disappear. These results may provide further support to Berlin and Kay's basic colour terms theory.  
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Notes CIC Approved no  
Call Number CAT @ cat @ BPV2009 Serial 1192  
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Author C. Alejandro Parraga; Javier Vazquez; Maria Vanrell edit  openurl
Title A new cone activation-based natural images dataset Type Journal Article
Year 2009 Publication Perception Abbreviated Journal PER  
Volume 36 Issue Pages 180  
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Abstract We generated a new dataset of digital natural images where each colour plane corresponds to the human LMS (long-, medium-, short-wavelength) cone activations. The images were chosen to represent five different visual environments (eg forest, seaside, mountain snow, urban, motorways) and were taken under natural illumination at different times of day. At the bottom-left corner of each picture there was a matte grey ball of approximately constant spectral reflectance (across the camera's response spectrum,) and nearly Lambertian reflective properties, which allows to compute (and remove, if necessary) the illuminant's colour and intensity. The camera (Sigma Foveon SD10) was calibrated by measuring its sensor's spectral responses using a set of 31 spectrally narrowband interference filters. This allowed conversion of the final camera-dependent RGB colour space into the Smith and Pokorny (1975) cone activation space by means of a polynomial transformation, optimised for a set of 1269 Munsell chip reflectances. This new method is an improvement over the usual 3 × 3 matrix transformation which is only accurate for spectrally-narrowband colours. The camera-to-LMS transformation can be recalculated to consider other non-human visual systems. The dataset is available to download from our website.  
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Series Editor Series Title Abbreviated Series Title (up)  
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Area Expedition Conference  
Notes CIC Approved no  
Call Number CAT @ cat @ PVV2009 Serial 1193  
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