994 resultados para color pattern


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Selecting a set of features which is optimal for a given task is the problem which plays an important role in a wide variety of contexts including pattern recognition, images understanding and machine learning. The concept of reduction of the decision table based on the rough set is very useful for feature selection. In this paper, a genetic algorithm based approach is presented to search the relative reduct decision table of the rough set. This approach has the ability to accommodate multiple criteria such as accuracy and cost of classification into the feature selection process and finds the effective feature subset for texture classification . On the basis of the effective feature subset selected, this paper presents a method to extract the objects which are higher than their surroundings, such as trees or forest, in the color aerial images. The experiments results show that the feature subset selected and the method of the object extraction presented in this paper are practical and effective.

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In this project, the main focus is to apply image processing techniques in computer vision through an omnidirectional vision system to agricultural mobile robots (AMR) used for trajectory navigation problems, as well as localization matters. To carry through this task, computational methods based on the JSEG algorithm were used to provide the classification and the characterization of such problems, together with Artificial Neural Networks (ANN) for pattern recognition. Therefore, it was possible to run simulations and carry out analyses of the performance of JSEG image segmentation technique through Matlab/Octave platforms, along with the application of customized Back-propagation algorithm and statistical methods as structured heuristics methods in a Simulink environment. Having the aforementioned procedures been done, it was practicable to classify and also characterize the HSV space color segments, not to mention allow the recognition of patterns in which reasonably accurate results were obtained. ©2010 IEEE.

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Communication contributes to mediate the interactions between plants and the animals that disperse their genes. As yet, seasonal patterns in plant-animal communication are unknown, even though many habitats display pronounced seasonality e.g. when leaves senescence. We thus hypothesized that the contrast between fruit displays and their background vary throughout the year in a seasonal habitat. If this variation is adaptive, we predicted higher contrasts between fruits and foliage during the fruiting season in a cerrado-savanna vegetation, southeastern Brazil. Based on a six-year data base of fruit ripening and a one-year data set of fruit biomass, we used reflectance measurements and contrast analysis to show that fruits with distinct colors differed in the beginning of ripening and the peak of fruit biomass. Black, and particularly red fruits, that have a high contrast against the leaf background, were highly seasonal, peaking in the wet season. Multicolored and yellow fruits were less seasonal, not limited to one season, with a bimodal pattern for yellow ones, represented by two peaks, one in each season. We further supported the hypothesis that seasonal changes in fruit contrasts can be adaptive because fruits contrasted more strongly against their own foliage in the wet season, when most fruits are ripe. Hence, the seasonal variation in fruit colors observed in the cerrado-savanna may be, at least partly, explicable as an adaptation to ensure high conspicuousness to seed dispersers. © 2013 The Authors.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Transient visual evoked cortical potentials (VECP) were recorded from the scalp of healthy normal trichromats (n = 12). VECPs were elicited by onset/offset presentation of patterned stimuli of two kinds: isochromatic luminance-modulated, and equiluminant red-green modulated, sine wave gratings. The amplitude and latency of the major onset components of the onset/offset VECP were measured and plotted as a function of the logarithm of pooled cone contrast. The early onset components, achromatic C1 and chromatic N1, increase linearly with log contrast, but N1 has a higher contrast gain than C1. The late onset components, achromatic C2 and chromatic N2, have similar contrast gain, and similar response as a function of contrast level: both increase in the low-to-medium range of contrasts and saturate at high contrast levels. In the range of pooled cone contrast tested, C1 and N1 show similar latencies, whilst C2 shows shorter latencies than N2. We suggest that C1 and N1 are generated by the same visual mechanism with high red-green contrast gain and low luminance contrast gain, whilst C2 and N2 are generated by different visual mechanisms.

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The present study aimed at providing conditions for the assessment of color discrimination in children using a modified version of the Cambridge Colour Test (CCT, Cambridge Research Systems Ltd., Rochester, UK). Since the task of indicating the gap of the Landolt C used in that test proved counterintuitive and/or difficult for young children to understand, we changed the target Stimulus to a patch of color approximately the size of the Landolt C gap (about 7 degrees Of Visual angle at 50 cm from the monitor). The modifications were performed for the CCT Trivector test which measures color discrimination for the protan, deutan and tritan confusion lines. Experiment I Sought to evaluate the correspondence between the CCT and the child-friendly adaptation with adult subjects (n = 29) with normal color vision. Results showed good agreement between the two test versions. Experiment 2 tested the child-friendly software with children 2 to 7 years old (n = 25) using operant training techniques for establishing and maintaining the subjects` performance. Color discrimination thresholds were progressively lower as age increased within the age range tested (2 to 30 years old), and the data-including those obtained for children-fell within the range of thresholds previously obtained for adults with the CCT. The protan and deutan thresholds were consistently lower than tritan thresholds, a pattern repeatedly observed in adults tested with the CCT. The results demonstrate that the test is fit for assessment of color discrimination in young children and may be a useful tool for the establishment of color vision thresholds during development.

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Color texture classification is an important step in image segmentation and recognition. The color information is especially important in textures of natural scenes, such as leaves surfaces, terrains models, etc. In this paper, we propose a novel approach based on the fractal dimension for color texture analysis. The proposed approach investigates the complexity in R, G and B color channels to characterize a texture sample. We also propose to study all channels in combination, taking into consideration the correlations between them. Both these approaches use the volumetric version of the Bouligand-Minkowski Fractal Dimension method. The results show a advantage of the proposed method over other color texture analysis methods. (C) 2011 Elsevier Ltd. All rights reserved.

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The identification of color vision types in primates is fundamental to understanding the evolution and biological function of color perception. The Hard, Randy, and Rittler (HRR) pseudoisochromatic test categorizes human color vision types successfully. Here we provide an experimental setup to employ HRR in a nonhuman primate, the capuchin (Cebus libidinosus), a platyrrhine with polymorphic color vision. The HRR test consists of plates with a matrix composed of gray circles that vary in size and brightness. Differently colored circles form a geometric shape (X, O, or Delta) that is discriminated visually from the gray background pattern. The ability to identify these shapes determines the type of dyschromatopsy (deficiency in color vision). We tested six capuchins in their own cages under natural sunlight. The subjects chose between two HRR plates in each trial: one with the gray pattern only and the other with a colored shape, presented on the left or right side at random. We presented the test 40 times and calculated the 95 % confidence limits for chance performance based on the binomial test. We also genotyped all subjects for exons 3 and 5 of the X-linked opsin genes. The HRR test diagnosed two subjects as protan dichromats (missing or defective L-cone), three as deutan dichromats (missing or defective M-cone), and one female as trichromat. Genetic analysis supported the behavioral data for all subjects. These findings show that the HRR test can be applied to diagnose color vision in nonhuman primates.

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[ES] El comportamiento agresivo del cangrejo moro (Grapsus grapsus) ante un modelo de competidor potencial no varió en función del color corporal de este último. No obstante, se observaron cambios en dicho comportamiento en función del tamaño del individuo residente, aumentado la intensidad de los ataques cuanto menores eran las asimetrías en talla

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Introduzione: Negli ultimi anni, il color-power Doppler si è dimostrato un utile strumento per valutare le alterazioni della vascolarizzazione della parete intestinale nelle patologie del tratto gastro-enterico. Più di recente, i mezzi di contrasto ecografici di II generazione associati all’ecografia real-time con basso indice meccanico (CEUS) hanno permesso di valutare ecograficamente il microcircolo, consentendo la valutazione della vascolarizzazione di parete nelle patologie associate a flogosi e neoangiogenesi. Studi recenti hanno documentato i pattern Doppler e CEUS nella malattia infiammatoria intestinale. Le alterazioni della vascolarizzazione di parete nella patologia neoplastica, invece, sono state finora valutate con sola tecnica Doppler. Recenti studi basati sull’impiego di tale metodica hanno in effetti dimostrato che l’intensità del segnale vascolare di parete correla con la variante istologica della neoplasia e con il suo grado di invasione vascolare costituendo così un parametro di neoangiogenesi tumorale. Pertanto, ottenere mediante CEUS una più accurata definizione del microcircolo di parete potrebbe aiutare nella diagnosi differenziale tra patologia infiammatoria e neoplastica dello stomaco e fornire utili informazioni per valutare l’ aggressività del cancro gastrico.

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The Earth's climate abruptly warmed by 5-8 °C during the Palaeocene-Eocene thermal maximum (PETM), about 55.5 million years ago**1,2. This warming was associated with a massive addition of carbon to the ocean-atmosphere system, but estimates of the Earth systemresponse to this perturbation are complicated by widely varying estimates of the duration of carbon release, which range from less than a year to tens of thousands of years. In addition the source of the carbon, and whether it was released as a single injection or in several pulses, remains the subject of debate**2-4. Here we present a new high-resolution carbon isotope record from terrestrial deposits in the Bighorn Basin (Wyoming, USA) spanning the PETM, and interpret the record using a carbon-cycle boxmodel of the ocean-atmosphere-biosphere system.Our record shows that the beginning of the PETMis characterized by not one but two distinct carbon release events, separated by a recovery to background values. To reproduce this pattern, our model requires two discrete pulses of carbon released directly to the atmosphere, at average rates exceeding 0.9 Pg C yr**-1, with the first pulse lasting fewer than 2,000 years.

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The apposition compound eyes of gonodactyloid stomatopods are divided into a ventral and a dorsal hemisphere by six equatorial rows of enlarged ommatidia, the mid-band (MB). Whereas the hemispheres are specialized for spatial vision, the MB consists of four dorsal rows of ommatidia specialized for colour vision and two ventral rows specialized for polarization vision. The eight retinula cell axons (RCAs) from each ommatidium project retinotopically onto one corresponding lamina cartridge, so that the three retinal data streams (spatial, colour and polarization) remain anatomically separated. This study investigates whether the retinal specializations are reflected in differences in the RCA arrangement within the corresponding lamina cartridges. We have found that, in all three eye regions, the seven short visual fibres (svfs) formed by retinula cells 1-7 (R1-R7) terminate at two distinct lamina levels, geometrically separating the terminals of photoreceptors sensitive to either orthogonal e-vector directions or different wavelengths of light. This arrangement is required for the establishment of spectral and polarization opponency mechanisms. The long visual fibres (lvfs) of the eighth retinula cells (R8) pass through the lamina and project retinotopically to the distal medulla externa. Differences between the three eye regions exist in the packing of svf terminals and in the branching patterns of the lvfs within the lamina. We hypothesize that the R8 cells of MB rows 1-4 are incorporated into the colour vision system formed by R1-R7, whereas the R8 cells of MB rows 5 and 6 form a separate neural channel from R1 to R7 for polarization processing.

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Calcitic belemnite rostra are usually employed to perform paleoenvironmental studies based on geochemical data. However, several questions, such as their original porosity and microstructure, remain open, despite they are essential to make accurate interpretations based on geochemical analyses.This paper revisits and enlightens some of these questions. Petrographic data demonstrate that calcite crystals of the rostrum solidum of belemnites grow from spherulites that successively develop along the apical line, resulting in a “regular spherulithic prismatic” microstructure. Radially arranged calcite crystals emerge and diverge from the spherulites: towards the apex, crystals grow until a new spherulite is formed; towards the external walls of the rostrum, the crystals become progressively bigger and prismatic. Adjacent crystals slightly vary in their c-axis orientation, resulting in undulose extinction. Concentric growth layering develops at different scales and is superimposed and traversed by a radial pattern, which results in the micro-fibrous texture that is observed in the calcite crystals in the rostra.Petrographic data demonstrate that single calcite crystals in the rostra have a composite nature, which strongly suggests that the belemnite rostra were originally porous. Single crystals consistently comprise two distinct zones or sectors in optical continuity: 1) the inner zone is fluorescent, has relatively low optical relief under transmitted light (TL) microscopy, a dark-grey color under backscatter electron microscopy (BSEM), a commonly triangular shape, a “patchy” appearance and relatively high Mg and Na contents; 2) the outer sector is non-fluorescent, has relatively high optical relief under TL, a light-grey color under BSEM and low Mg and Na contents. The inner and fluorescent sectors are interpreted to have formed first as a product of biologically controlled mineralization during belemnite skeletal growth and the non-fluorescent outer sectors as overgrowths of the former, filling the intra- and inter-crystalline porosity. This question has important implications for making paleoenvironmental and/or paleoclimatic interpretations based on geochemical analyses of belemnite rostra.Finally, the petrographic features of composite calcite crystals in the rostra also suggest the non-classical crystallization of belemnite rostra, as previously suggested by other authors.

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Enterprise Application Integration (EAI) is a challenging area that is attracting growing attention from the software industry and the research community. A landscape of languages and techniques for EAI has emerged and is continuously being enriched with new proposals from different software vendors and coalitions. However, little or no effort has been dedicated to systematically evaluate and compare these languages and techniques. The work reported in this paper is a first step in this direction. It presents an in-depth analysis of a language, namely the Business Modeling Language, specifically developed for EAI. The framework used for this analysis is based on a number of workflow and communication patterns. This framework provides a basis for evaluating the advantages and drawbacks of EAI languages with respect to recurrent problems and situations.