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| Author | Olivier Penacchio; C. Alejandro Parraga; Maria Vanrell |
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| Title | Natural Scene Statistics account for Human Cones Ratios | Type | Journal Article | |||
Year  |
2010 | Publication | Perception. ECVP Abstract Supplement | Abbreviated Journal | PER | |
| Volume | 39 | Issue | Pages | 101 | ||
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| Abstract | In two previous experiments [Parraga et al, 2009 J. of Im. Sci. and Tech 53(3) 031106; Benavente et al,2009 Perception 38 ECVP Supplement, 36] the boundaries of basic colour categories were measured.
In the first experiment, samples were presented in isolation (ie on a dark background) and boundaries were measured using a yes/no paradigm. In the second, subjects adjusted the chromaticity of a sample presented on a random Mondrian background to find the boundary between pairs of adjacent colours. Results from these experiments showed significant di erences but it was not possible to conclude whether this discrepancy was due to the absence/presence of a colourful background or to the di erences in the paradigms used. In this work, we settle this question by repeating the first experiment (ie samples presented on a dark background) using the second paradigm. A comparison of results shows that although boundary locations are very similar, boundaries measured in context are significantly di erent(more di use) than those measured in isolation (confirmed by a Student’s t-test analysis on the subject’s answers statistical distributions). In addition, we completed the mapping of colour name space by measuring the boundaries between chromatic colours and the achromatic centre. With these results we completed our parametric fuzzy-sets model of colour naming space. |
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| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ PPV2010 | Serial | 1357 | |||
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| Author | Robert Benavente; C. Alejandro Parraga; Maria Vanrell |
 
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| Title | La influencia del contexto en la definicion de las fronteras entre las categorias cromaticas | Type | Conference Article | |||
| Year |
2010 | Publication | 9th Congreso Nacional del Color | Abbreviated Journal | ||
| Volume | Issue | Pages | 92–95 | |||
| Keywords | Categorización del color; Apariencia del color; Influencia del contexto; Patrones de Mondrian; Modelos paramétricos | |||||
| Abstract | En este artículo presentamos los resultados de un experimento de categorización de color en el que las muestras se presentaron sobre un fondo multicolor (Mondrian) para simular los efectos del contexto. Los resultados se comparan con los de un experimento previo que, utilizando un paradigma diferente, determinó las fronteras sin tener en cuenta el contexto. El análisis de los resultados muestra que las fronteras obtenidas con el experimento en contexto presentan menos confusión que las obtenidas en el experimento sin contexto. | |||||
| Address | Alicante (Spain) | |||||
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| ISSN | ISBN | 978-84-9717-144-1 | Medium | |||
| Area | Expedition | Conference | CNC | |||
| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ BPV2010 | Serial | 1327 | |||
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| Author | Susana Alvarez; Anna Salvatella; Maria Vanrell; Xavier Otazu |
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| Title | 3D Texton Spaces for color-texture retrieval | Type | Conference Article | |||
| Year |
2010 | Publication | 7th International Conference on Image Analysis and Recognition | Abbreviated Journal | ||
| Volume | 6111 | Issue | Pages | 354–363 | ||
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| Abstract | Color and texture are visual cues of different nature, their integration in an useful visual descriptor is not an easy problem. One way to combine both features is to compute spatial texture descriptors independently on each color channel. Another way is to do the integration at the descriptor level. In this case the problem of normalizing both cues arises. In this paper we solve the latest problem by fusing color and texture through distances in texton spaces. Textons are the attributes of image blobs and they are responsible for texture discrimination as defined in Julesz’s Texton theory. We describe them in two low-dimensional and uniform spaces, namely, shape and color. The dissimilarity between color texture images is computed by combining the distances in these two spaces. Following this approach, we propose our TCD descriptor which outperforms current state of art methods in the two different approaches mentioned above, early combination with LBP and late combination with MPEG-7. This is done on an image retrieval experiment over a highly diverse texture dataset from Corel. | |||||
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| Publisher | Springer Berlin Heidelberg | Place of Publication | Editor | A.C. Campilho and M.S. Kamel | ||
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| Series Editor | Series Title | Abbreviated Series Title | LNCS | |||
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| ISSN | 0302-9743 | ISBN | 978-3-642-13771-6 | Medium | ||
| Area | Expedition | Conference | ICIAR | |||
| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ ASV2010a | Serial | 1325 | |||
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| Author | Susana Alvarez; Anna Salvatella; Maria Vanrell; Xavier Otazu |
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| Title | Perceptual color texture codebooks for retrieving in highly diverse texture datasets | Type | Conference Article | |||
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2010 | Publication | 20th International Conference on Pattern Recognition | Abbreviated Journal | ||
| Volume | Issue | Pages | 866–869 | |||
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| Abstract | Color and texture are visual cues of different nature, their integration in a useful visual descriptor is not an obvious step. One way to combine both features is to compute texture descriptors independently on each color channel. A second way is integrate the features at a descriptor level, in this case arises the problem of normalizing both cues. A significant progress in the last years in object recognition has provided the bag-of-words framework that again deals with the problem of feature combination through the definition of vocabularies of visual words. Inspired in this framework, here we present perceptual textons that will allow to fuse color and texture at the level of p-blobs, which is our feature detection step. Feature representation is based on two uniform spaces representing the attributes of the p-blobs. The low-dimensionality of these text on spaces will allow to bypass the usual problems of previous approaches. Firstly, no need for normalization between cues; and secondly, vocabularies are directly obtained from the perceptual properties of text on spaces without any learning step. Our proposal improve current state-of-art of color-texture descriptors in an image retrieval experiment over a highly diverse texture dataset from Corel. | |||||
| Address | Istanbul (Turkey) | |||||
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| ISSN | 1051-4651 | ISBN | 978-1-4244-7542-1 | Medium | ||
| Area | Expedition | Conference | ICPR | |||
| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ ASV2010b | Serial | 1426 | |||
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| Author | Xavier Otazu; C. Alejandro Parraga; Maria Vanrell |
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| Title | Towards a unified chromatic inducction model | Type | Journal Article | |||
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2010 | Publication | Journal of Vision | Abbreviated Journal | VSS | |
| Volume | 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 | C. Alejandro Parraga; Javier Vazquez; Maria Vanrell |
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| 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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| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ PVV2009 | Serial | 1193 | |||
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| Author | C. Alejandro Parraga; Robert Benavente; Maria Vanrell; Ramon Baldrich |
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| 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 | Fahad Shahbaz Khan; Joost Van de Weijer; Maria Vanrell |
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| Title | Top-Down Color Attention for Object Recognition | Type | Conference Article | |||
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2009 | Publication | 12th International Conference on Computer Vision | Abbreviated Journal | ||
| Volume | Issue | Pages | 979 - 986 | |||
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| Abstract | Generally the bag-of-words based image representation follows a bottom-up paradigm. The subsequent stages of the process: feature detection, feature description, vocabulary construction and image representation are performed independent of the intentioned object classes to be detected. In such a framework, combining multiple cues such as shape and color often provides below-expected results. This paper presents a novel method for recognizing object categories when using multiple cues by separating the shape and color cue. Color is used to guide attention by means of a top-down category-specific attention map. The color attention map is then further deployed to modulate the shape features by taking more features from regions within an image that are likely to contain an object instance. This procedure leads to a category-specific image histogram representation for each category. Furthermore, we argue that the method combines the advantages of both early and late fusion. We compare our approach with existing methods that combine color and shape cues on three data sets containing varied importance of both cues, namely, Soccer ( color predominance), Flower (color and shape parity), and PASCAL VOC Challenge 2007 (shape predominance). The experiments clearly demonstrate that in all three data sets our proposed framework significantly outperforms the state-of-the-art methods for combining color and shape information. | |||||
| Address | Kyoto, Japan | |||||
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| ISSN | 1550-5499 | ISBN | 978-1-4244-4420-5 | Medium | ||
| Area | Expedition | Conference | ICCV | |||
| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ SWV2009 | Serial | 1196 | |||
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| Author | Javier Vazquez; C. Alejandro Parraga; Maria Vanrell |
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| Title | Ordinal pairwise method for natural images comparison | Type | Journal Article | |||
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2009 | Publication | Perception | Abbreviated Journal | PER | |
| Volume | 38 | Issue | Pages | 180 | ||
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| 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 | Javier Vazquez; C. Alejandro Parraga; Maria Vanrell; Ramon Baldrich |
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| Title | Color Constancy Algorithms: Psychophysical Evaluation on a New Dataset | Type | Journal Article | |||
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2009 | Publication | Journal of Imaging Science and Technology | Abbreviated Journal | ||
| Volume | 53 | Issue | 3 | Pages | 031105–9 | |
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| 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 | Robert Benavente; C. Alejandro Parraga; Maria Vanrell |
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| 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; Robert Benavente; Maria Vanrell; Ramon Baldrich |
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| Title | Modelling Inter-Colour Regions of Colour Naming Space | Type | Conference Article | |||
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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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| Area | Expedition | Conference | CGIV08 | |||
| Notes | CAT;CIC | Approved | no | |||
| Call Number | CAT @ cat @ PBV2008 | Serial | 969 | |||
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| Author | Eduard Vazquez; Maria Vanrell |
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| Title | Eines per al desenvolupament de competencies de enginyeria en un assignatura de Intel·ligencia Artificial | Type | Miscellaneous | |||
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2008 | Publication | V Jornades d’Innovacio Docent (UAB) | Abbreviated Journal | ||
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| Address | Bellaterra (Spain) | |||||
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| Notes | CIC | Approved | no | |||
| Call Number | CAT @ cat @ VaV2008 | Serial | 1011 | |||
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| Author | Javier Vazquez; Maria Vanrell; Ramon Baldrich |
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| Title | Towards a Psychophysical Evaluation of Colour Constancy Algorithms | Type | Conference Article | |||
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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) | |||||
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| Area | Expedition | Conference | CGIV08 | |||
| Notes | CAT;CIC | Approved | no | |||
| Call Number | CAT @ cat @ VVB2008a | Serial | 968 | |||
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