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Author | Jaime Moreno; Xavier Otazu; Maria Vanrell |
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Title | Contribution of CIWaM in JPEG2000 Quantization for Color Images | Type | Conference Article | |||
Year | 2010 | Publication | Proceedings of The CREATE 2010 Conference | Abbreviated Journal | ||
Volume | Issue | Pages | 132–136 | |||
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Abstract | The aim of this work is to explain how to apply perceptual concepts to define a perceptual pre-quantizer and to improve JPEG2000 compressor. The approach consists in quantizing wavelet transform coefficients using some of the human visual system behavior properties. Noise is fatal to image compression performance, because it can be both annoying for the observer and consumes excessive bandwidth when the imagery is transmitted. Perceptual pre-quantization reduces unperceivable details and thus improve both visual impression and transmission properties. The comparison between JPEG2000 without and with perceptual pre-quantization shows that the latter is not favorable in PSNR, but the recovered image is more compressed at the same or even better visual quality measured with a weighted PSNR. Perceptual criteria were taken from the CIWaM(ChromaticInductionWaveletModel). | |||||
Address | Gjovik (Norway) | |||||
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Area | Expedition | Conference | CREATE | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ MOV2010b | Serial | 1308 | |||
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Author | C. Alejandro Parraga; Ramon Baldrich; Maria Vanrell |
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Title | Accurate Mapping of Natural Scenes Radiance to Cone Activation Space: A New Image Dataset | Type | Conference Article | |||
Year | 2010 | Publication | 5th European Conference on Colour in Graphics, Imaging and Vision and 12th International Symposium on Multispectral Colour Science | Abbreviated Journal | ||
Volume | Issue | Pages | 50–57 | |||
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Abstract | The characterization of trichromatic cameras is usually done in terms of a device-independent color space, such as the CIE 1931 XYZ space. This is indeed convenient since it allows the testing of results against colorimetric measures. We have characterized our camera to represent human cone activation by mapping the camera sensor's (RGB) responses to human (LMS) through a polynomial transformation, which can be “customized” according to the types of scenes we want to represent. Here we present a method to test the accuracy of the camera measures and a study on how the choice of training reflectances for the polynomial may alter the results. | |||||
Address | Joensuu, Finland | |||||
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ISSN | ISBN | 9781617388897 | Medium | |||
Area | Expedition | Conference | CGIV/MCS | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ PBV2010a | Serial | 1322 | |||
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Author | Javier Vazquez; G. D. Finlayson; Maria Vanrell |
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Title | A compact singularity function to predict WCS data and unique hues | Type | Conference Article | |||
Year | 2010 | Publication | 5th European Conference on Colour in Graphics, Imaging and Vision and 12th International Symposium on Multispectral Colour Science | Abbreviated Journal | ||
Volume | Issue | Pages | 33–38 | |||
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Abstract | Understanding how colour is used by the human vision system is a widely studied research field. The field, though quite advanced, still faces important unanswered questions. One of them is the explanation of the unique hues and the assignment of color names. This problem addresses the fact of different perceptual status for different colors.
Recently, Philipona and O'Regan have proposed a biological model that allows to extract the reflection properties of any surface independently of the lighting conditions. These invariant properties are the basis to compute a singularity index that predicts the asymmetries presented in unique hues and basic color categories psychophysical data, therefore is giving a further step in their explanation. In this paper we build on their formulation and propose a new singularity index. This new formulation equally accounts for the location of the 4 peaks of the World colour survey and has two main advantages. First, it is a simple elegant numerical measure (the Philipona measurement is a rather cumbersome formula). Second, we develop a colour-based explanation for the measure. |
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Address | Joensuu, Finland | |||||
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Language | Summary Language | Original Title | ||||
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ISSN | ISBN | 9781617388897 | Medium | |||
Area | Expedition | Conference | CGIV/MCS | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ VFV2010 | Serial | 1324 | |||
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Author | C. Alejandro Parraga; Robert Benavente; Maria Vanrell |
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Title | Towards a general model of colour categorization which considers context | Type | Journal Article | |||
Year | 2010 | Publication | Perception. ECVP Abstract Supplement | Abbreviated Journal | PER | |
Volume | 39 | Issue | Pages | 86 | ||
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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 dierences but it was not possible to conclude whether this discrepancy was due to the absence/presence of a colourful background or to the dierences 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 dierent(more diuse) 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 @ PBV2010b | Serial | 1326 | |||
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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 | Javier Vazquez; Maria Vanrell; Robert Benavente |
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Title | Color names as a constraint for Computer Vision problems | Type | Conference Article | |||
Year | 2010 | Publication | Proceedings of The CREATE 2010 Conference | Abbreviated Journal | ||
Volume | Issue | Pages | 324–328 | |||
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Abstract | Computer Vision Problems are usually ill-posed. Constraining de gamut of possible solutions is then a necessary step. Many constrains for different problems have been developed during years. In this paper, we present a different way of constraining some of these problems: the use of color names. In particular, we will focus on segmentation, representation ans constancy. | |||||
Address | Gjovik (Norway) | |||||
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Area | Expedition | Conference | CREATE | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ VVB2010 | Serial | 1328 | |||
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Author | Fahad Shahbaz Khan; Joost Van de Weijer; Maria Vanrell |
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Title | Who Painted this Painting? | Type | Conference Article | |||
Year | 2010 | Publication | Proceedings of The CREATE 2010 Conference | Abbreviated Journal | ||
Volume | Issue | Pages | 329–333 | |||
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Address | Gjovik (Norway) | |||||
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Area | Expedition | Conference | CREATE | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ KWV2010 | Serial | 1329 | |||
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Author | Shida Beigpour; Joost Van de Weijer |
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Title | Photo-Realistic Color Alteration for Architecture and Design | Type | Conference Article | |||
Year | 2010 | Publication | Proceedings of The CREATE 2010 Conference | Abbreviated Journal | ||
Volume | Issue | Pages | 84–88 | |||
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Abstract | As color is a strong stimuli we receive from the exterior world, choosing the right color can prove crucial in creating the desired architecture and desing. We propose a framework to apply a realistic color change on both objects and their illuminant lights for snapshots of architectural designs, in order to visualize and choose the right color before actully applying the change in the real world. The proposed framework is based on the laws of physics in order to accomplish realistic and physically plausible results. | |||||
Address | Gjovik (Norway) | |||||
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ISSN | ISBN | Medium | ||||
Area | Expedition | Conference | CREATE | |||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ BeW2010 | Serial | 1330 | |||
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Author | Marc Serra |
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Title | Estimating Intrinsic Images from Physical and Categorical Color Cues | Type | Report | |||
Year | 2010 | Publication | CVC Technical Report | Abbreviated Journal | ||
Volume | 151 | Issue | Pages | |||
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Corporate Author | Thesis | Master's thesis | ||||
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Area | Expedition | Conference | ||||
Notes | CIC | Approved | no | |||
Call Number | Admin @ si @ Ser2010 | Serial | 1345 | |||
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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 dierences but it was not possible to conclude whether this discrepancy was due to the absence/presence of a colourful background or to the dierences 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 dierent(more diuse) 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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Area | Expedition | Conference | ||||
Notes | CIC | Approved | no | |||
Call Number | CAT @ cat @ PPV2010 | Serial | 1357 | |||
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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 | |||
Year | 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 | |||
Year | 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 | Enric Marti; Jordi Rocarias; Ricardo Toledo |
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Title | Caront: gestió flexible de grups d’alumnes en una asignatura i activitats sobre grups. Nova activitat de control | Type | Miscellaneous | |||
Year | 2008 | Publication | V Jornades d’Innovació Docent | Abbreviated Journal | ||
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Notes | IAM;RV;CIC;ADAS | Approved | no | |||
Call Number | IAM @ iam @ MRT2008a | Serial | 1617 | |||
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Author | Ernest Valveny; Ricardo Toledo; Ramon Baldrich; Enric Marti |
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Title | Combining recognition-based in segmentation-based approaches for graphic symol recognition using deformable template matching | Type | Conference Article | |||
Year | 2002 | Publication | Proceeding of the Second IASTED International Conference Visualization, Imaging and Image Proceesing VIIP 2002 | Abbreviated Journal | ||
Volume | Issue | Pages | 502–507 | |||
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Notes | DAG;RV;CAT;IAM;CIC;ADAS | Approved | no | |||
Call Number | IAM @ iam @ VTB2002 | Serial | 1660 | |||
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Author | Arjan Gijsenij; Theo Gevers; Joost Van de Weijer |
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Title | Computational Color Constancy: Survey and Experiments | Type | Journal Article | |||
Year | 2011 | Publication | IEEE Transactions on Image Processing | Abbreviated Journal | TIP | |
Volume | 20 | Issue | 9 | Pages | 2475-2489 | |
Keywords | computational color constancy;computer vision application;gamut-based method;learning-based method;static method;colour vision;computer vision;image colour analysis;learning (artificial intelligence);lighting | |||||
Abstract | Computational color constancy is a fundamental prerequisite for many computer vision applications. This paper presents a survey of many recent developments and state-of-the- art methods. Several criteria are proposed that are used to assess the approaches. A taxonomy of existing algorithms is proposed and methods are separated in three groups: static methods, gamut-based methods and learning-based methods. Further, the experimental setup is discussed including an overview of publicly available data sets. Finally, various freely available methods, of which some are considered to be state-of-the-art, are evaluated on two data sets. | |||||
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ISSN | 1057-7149 | ISBN | Medium | |||
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Notes | ISE;CIC | Approved | no | |||
Call Number | Admin @ si @ GGW2011 | Serial | 1717 | |||
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Author | Xavier Boix; Josep M. Gonfaus; Joost Van de Weijer; Andrew Bagdanov; Joan Serrat; Jordi Gonzalez |
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Title | Harmony Potentials: Fusing Global and Local Scale for Semantic Image Segmentation | Type | Journal Article | |||
Year | 2012 | Publication | International Journal of Computer Vision | Abbreviated Journal | IJCV | |
Volume | 96 | Issue | 1 | Pages | 83-102 | |
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Abstract | The Hierarchical Conditional Random Field(HCRF) model have been successfully applied to a number of image labeling problems, including image segmentation. However, existing HCRF models of image segmentation do not allow multiple classes to be assigned to a single region, which limits their ability to incorporate contextual information across multiple scales.
At higher scales in the image, this representation yields an oversimplied model since multiple classes can be reasonably expected to appear within large regions. This simplied model particularly limits the impact of information at higher scales. Since class-label information at these scales is usually more reliable than at lower, noisier scales, neglecting this information is undesirable. To address these issues, we propose a new consistency potential for image labeling problems, which we call the harmony potential. It can encode any possible combi- nation of labels, penalizing only unlikely combinations of classes. We also propose an eective sampling strategy over this expanded label set that renders tractable the underlying optimization problem. Our approach obtains state-of-the-art results on two challenging, standard benchmark datasets for semantic image segmentation: PASCAL VOC 2010, and MSRC-21. |
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ISSN | 0920-5691 | ISBN | Medium | |||
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Notes | ISE;CIC;ADAS | Approved | no | |||
Call Number | Admin @ si @ BGW2012 | Serial | 1718 | |||
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Author | Olivier Penacchio; C. Alejandro Parraga |
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Title | What is the best criterion for an efficient design of retinal photoreceptor mosaics? | Type | Journal Article | |||
Year | 2011 | Publication | Perception | Abbreviated Journal | PER | |
Volume | 40 | Issue | Pages | 197 | ||
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Abstract | The proportions of L, M and S photoreceptors in the primate retina are arguably determined by evolutionary pressure and the statistics of the visual environment. Two information theory-based approaches have been recently proposed for explaining the asymmetrical spatial densities of photoreceptors in humans. In the first approach Garrigan et al (2010 PLoS ONE 6 e1000677), a model for computing the information transmitted by cone arrays which considers the differential blurring produced by the long-wavelength accommodation of the eye’s lens is proposed. Their results explain the sparsity of S-cones but the optimum depends weakly on the L:M cone ratio. In the second approach (Penacchio et al, 2010 Perception 39 ECVP Supplement, 101), we show that human cone arrays make the visual representation scale-invariant, allowing the total entropy of the signal to be preserved while decreasing individual neurons’ entropy in further retinotopic representations. This criterion provides a thorough description of the distribution of L:M cone ratios and does not depend on differential blurring of the signal by the lens. Here, we investigate the similarities and differences of both approaches when applied to the same database. Our results support a 2-criteria optimization in the space of cone ratios whose components are arguably important and mostly unrelated.
[This work was partially funded by projects TIN2010-21771-C02-1 and Consolider-Ingenio 2010-CSD2007-00018 from the Spanish MICINN. CAP was funded by grant RYC-2007-00484] |
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Notes | CIC | Approved | no | |||
Call Number | Admin @ si @ PeP2011a | Serial | 1719 | |||
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Author | C. Alejandro Parraga; Olivier Penacchio; Maria Vanrell |
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Title | Retinal Filtering Matches Natural Image Statistics at Low Luminance Levels | Type | Journal Article | |||
Year | 2011 | Publication | Perception | Abbreviated Journal | PER | |
Volume | 40 | Issue | Pages | 96 | ||
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Abstract | The assumption that the retina’s main objective is to provide a minimum entropy representation to higher visual areas (ie efficient coding principle) allows to predict retinal filtering in space–time and colour (Atick, 1992 Network 3 213–251). This is achieved by considering the power spectra of natural images (which is proportional to 1/f2) and the suppression of retinal and image noise. However, most studies consider images within a limited range of lighting conditions (eg near noon) whereas the visual system’s spatial filtering depends on light intensity and the spatiochromatic properties of natural scenes depend of the time of the day. Here, we explore whether the dependence of visual spatial filtering on luminance match the changes in power spectrum of natural scenes at different times of the day. Using human cone-activation based naturalistic stimuli (from the Barcelona Calibrated Images Database), we show that for a range of luminance levels, the shape of the retinal CSF reflects the slope of the power spectrum at low spatial frequencies. Accordingly, the retina implements the filtering which best decorrelates the input signal at every luminance level. This result is in line with the body of work that places efficient coding as a guiding neural principle. | |||||
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Notes | CIC | Approved | no | |||
Call Number | Admin @ si @ PPV2011 | Serial | 1720 | |||
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