Color Pairs Research Articles

Area Dominates Edge in Pointillistic Colour.

In Pointillism and Divisionism, artists moved from tonal to chromatic palettes, as Impressionism did before them, and relied on what is often called optical mixture instead of stirring paints together. The so-called optical mixture is actually not an optical mixture, but a mental blend, because the texture of the paint marks is used as a means to stress the picture plane. The touches are intended to remain separately visible. These techniques require novel methods of colour description that have to depart from standard colorimetric conventions. We investigate the distinctiveness of transitions between regions as defined through such artistic techniques. We find that the pointillist edges are not primarily defined by luminance contrast but are achieved in almost purely chromatic ways. A very simple rule suffices to predict transition distinctiveness for pairs of cardinal colours (yellow, green, cyan, blue, magenta, and red); it is simply distance along the colour circle or in the RGB cube. Distinctiveness of partition depends mainly on the colours of the regions, not the sharpness of the transition.

Sex differences in face but not colour learning in Polistes fuscatus paper wasps

When males and females have distinct behaviour, learning may vary between the sexes. Polistes fuscatus wasps provide an interesting model to study sex differences in learning because males and females have different social behaviour. Female wasps have highly variable facial patterns used for individual face recognition, live in cooperative groups where interactions depend on individual face recognition and excel at learning female faces. In contrast, male wasps lack the type of variable facial patterns necessary for individual face recognition and do not participate in the type of social interactions known to favour individual recognition in females. Instead, males leave the nest soon after adulthood and devote their energy to mating. Given the behavioural differences between males and females, females may be more adept at learning wasp faces than males. Here, we train male and female P. fuscatus to discriminate between pairs of female P. fuscatus face images and pairs of colours. Females learned to discriminate between pairs of face images more accurately than males. However, males and females were equally adept at colour learning, indicating that there are no generalized sex differences in learning. The sex differences in face, but not colour, learning are consistent with the adaptive specialization hypothesis, which posits that cognitive abilities are selected to solve particular social or ecological problems. Overall, general learning capacity is similar across male and female wasps, but face learning is shaped by sex-specific recognition behaviour.

Novel Perceptually Uniform Chromatic Space.

Chromatically perceptive observers are endowed with a sense of similarity between colors. For example, two shades of green that are only slightly discriminable are perceived as similar, whereas other pairs of colors, for example, blue and yellow, typically elicit markedly different sensations. The notion of similarity need not be shared by different observers. Dichromat and trichromat subjects perceive colors differently, and two dichromats (or two trichromats, for that matter) may judge chromatic differences inconsistently. Moreover, there is ample evidence that different animal species sense colors diversely. To capture the subjective metric of color perception, here we construct a notion of distance in color space based on the physiology of the retina, and is thereby individually tailored for different observers. By applying the Fisher metric to an analytical model of color representation, we construct a notion of distance that reproduces behavioral experiments of classical discrimination tasks. We then derive a coordinate transformation that defines a new chromatic space in which the Euclidean distance between any two colors is equal to the perceptual distance, as seen by one individual subject, endowed with an arbitrary number of color-sensitive photoreceptors, each with arbitrary absorption probability curves and appearing in arbitrary proportions.

Spectrum Graph Coloring and Applications to Wi-Fi Channel Assignment

We introduce and explore a family of vertex-coloring problems, which, surprisingly enough, have not been considered before despite stemming from the problem of Wi-Fi channel assignment. Given a spectrum of colors, endowed with a matrix of interferences between each pair of colors, the Threshold Spectrum Coloring problem fixes the number of colors available and aims to minimize the interference threshold, i.e., the maximum of the interferences at the vertices. Conversely, the Chromatic Spectrum Coloring problem fixes a threshold and aims to minimize the number of colors for which respecting that threshold is possible. As the main theoretical results, we prove tight upper bounds for the solutions to each problem. Since both problems turn out to be NP-hard, we complete the scene with experimental results. We propose a DSATUR-based heuristic and study its performance to minimize the maximum vertex interference in Wi-Fi channel assignment, both for randomly-generated graphs and for a real-world scenario. Further, for all these graphs, we experimentally check the goodness of the theoretical bounds.

Chunking in working memory via content-free labels

A recent study found that visual working memory performance was enhanced when pairs of colors were predictably paired, and it was interpreted as a form of “memory compression” which implies that more colors could be stored online in a more efficient format. Here we propose an alternative hypothesis that does not entail any increase in the number of individuated representations stored online. Instead, familiar ensembles of items may be attached to a content-free label (e.g., remembering red-white-blue as “American flag”) that can be used to retrieve the constituents of a chunk when they are needed to guide a response. If accessing “compressed” memories requires an additional retrieval process, then access to compressed items should be slower than for uncompressed items. Indeed, Experiments 1 (visual) and 2 (verbal) showed that response times were substantially longer in patterned (i.e., compressed) than in control conditions. In Experiments 3 and 4, regularity-based advantages were eliminated with brief (1000 or 875 ms) response deadlines, in line with our hypothesis that accessing compressed memories requires a slow retrieval process. In sum, while statistical regularities can enable access to larger amounts of information, this information may not be available “online” in the same way as singleton items.

The colour lexicon of the Serbian language - a study of dark blue and dark red colour categories Part 2: Categorical facilitation with Serbian colour terms

Part 1 of this study (Jakovljev & Zdravkovic, 2018) isolated two frequent and salient non- BCTs in the Serbian language: teget ?dark blue? and bordo ?dark red?, that segregate the blue and the red part of the colour space respectively. Now we conducted two experiments to additionally test the cognitive salience of these terms, investigating whether they can produce the category effects in a colour discrimination task. We demonstrated within? and between-participants agreement about the placement of the boundary in the blue and the red part of the colour space, additionally showing that Serbian speakers have distinctive representations of these categories. Analysis of RT in the discrimination task showed category effects ? participants were faster when discriminating colour pairs that belong to different linguistic categories than the pairs from the same category. These results for the first time demonstrated category effect in the Serbian language as well as the category effect in speeded discrimination of the red part of the colour space for any language. They also support views that category effect is linked to higher cognitive processes; hence it can be language specific.

A study of single colors and color pairs to communicate basic tastes

<b>A study of single colors and color pairs to communicate basic tastes</b>

In vitro evaluation of color and translucency reproduction of maxillofacial prostheses using a computerized system.

PURPOSEAccurate color matching of maxillofacial prostheses to skin is important for esthetics. A computerized color matching system specific to human skin has recently been developed. The purpose of this study was to evaluate the accuracy in color and translucency matching of the computerized color matching system across different skin colors.MATERIALS AND METHODSThe silicone was colored to simulate 28 different skin colors (n=5) to serve as “target skin colors”. Using a spectrocolorometer (e-skin), color codes were determined for “replicate skin color” fabrication. CIELAB Delta-E between target skin color-replicate skin color pairs and translucency parameter were calculated. CIELAB Delta-E values were compared with one-way ANOVA and Tukey multiple-comparison. The agreement between L*, a*, b* and translucency parameter of target skin colors and replicate skin color were calculated by a two-way mixed average measures intraclass correlation coefficient. Translucency parameter of target skin color-replicate skin color pairs were compared with Paired t-test (α=.05).RESULTSThe mean CIELAB Delta-E value was 3.83 and significant differences were found among colors. The intraclass correlation coefficient showed excellent reliability for L*, a*, b* and good reliability for translucency parameter (P<.001). The mean translucency parameter of replicate skin colors was significantly higher than that of translucency parameter.CONCLUSIONThe computerized color matching system specific to human skin was found to be reliable in terms of color and translucency between target skin colors and replicate skin color.

Coloring your information: How designers use Theory of Color in creative ways to present infographic

Various methods of data presentation is now visualized through engaging infographics and perform the presentation techniques a new kind of storytelling. Geometric elements for infographics perform interesting data, which is developed with color harmony. There are categories of colors based on color circle from the theory of color design: primary color, secondary color and tertiary color. This color circle allows a designer to visualize the balance and harmony of colors when they are side by side. These composition of colors can be formed as a harmonious dyad, triad, or tetrads. A harmonious dyad is formed from two diametrically opposed colors on the color circle, which known as contrast complementary and works best in color harmonious if one of the colors is dominant. A harmonious triad is represented by three colors from the color circle which positions with an equilateral triangle. An triangle of yellow-red-blue shows the most powerful of harmonious triad and call as the fundamental triad. A harmonious tetrad is developed from two pairs of complementary colors, which can be formed by rectangle or square on the color circle. It help to figure out how objects are connected on presenting data. To create an efficiency infographic, presenting data has to prepare with some strategic. The color circle has the power to perform the infographic when it is made for a fascinating design.

KaTie: For parton-level event generation with [formula omitted]-dependent initial states

KaTie is a parton-level event generator for hadron scattering processes that can deal with partonic initial-state momenta with an explicit transverse momentum dependence causing them to be space-like. Provided with the necessary transverse momentum dependent parton density functions, it calculates the tree-level off-shell matrix elements and performs the phase space importance sampling to produce weighted events, for example in the Les Houches Event File format. It can deal with arbitrary processes within the Standard Model, for up to at least four final-state particles. Furthermore, it can produce events for single-parton scattering as well as for multi-parton scattering. Program summaryProgram Title:KaTieProgram Files doi:http://dx.doi.org/10.17632/yrtgg8w9k8.1Licensing provisions: GPLv3Programming language: Fortran 2003 (implemented at least as far as in for example gfortran-4.6), Python (2.x with x≥6 or 3.x), BashExternal routines/libraries: Requires avhlib [1] and LHAPDF-6.x [2]Nature of problem: Factorization prescriptions for the cross section calculation of hadron scattering processes that allow for non-vanishing transverse momentum components for the initial-state partons require matrix elements with off-shell initial-state partons. Furthermore, the calculation of such cross sections requires the integration over these initial-state degrees of freedom, besides the components along the colliding hadrons and the final-state phase space degrees of freedom.Solution method: The Monte Carlo method is applied to create event files with which distributions for arbitrary observables can be evaluated. Tree-level off-shell matrix elements are defined as proposed in [3] and evaluated using Dyson–Schwinger recursion [4]. The whole procedure is automated for any process within the Standard Model, including the full particle content with all mass and coupling dependencies except the CKM matrix, but including the Higgs–gluon and Higgs–photon effective interactions.Restrictions: The matrix elements are tree-level matrix elements, and the maximal number of final-state particles is 9. The maximal number (initial plus final) of color pairs (gluons and/or quark–antiquark-pairs) for reasonable execution time is 6. Processes are restricted to the Standard Model, including the Higgs–gluon and Higgs–photon effective interactions.[1] M. Bury and A. van Hameren, Numerical evaluation of multi-gluon amplitudes for High Energy Factorization, Comput. Phys. Commun196 (2015) 592. http://bitbucket.org/hameren/avhlib[2] A. Buckley, J. Ferrando, S. Lloyd, K. Nordström, B. Page, M. Rüfenacht, M. Schönherr and G. Watt, LHAPDF6: parton density access in the LHC precision era, Eur. Phys. J. C75 (2015) 132. http://lhapdf.hepforge.org/[3] A. van Hameren, P. Kotko, and K. Kutak, Helicity amplitudes for high-energy scattering, JHEP01 (2013) 078.[4] F. Caravaglios and M. Moretti, An algorithm to compute Born scattering amplitudes without Feynman graphs, Phys. Lett. B358 (1995) 332. A. Kanaki, C.G. Papadopoulos, HELAC: A Package to compute electroweak helicity amplitudes, Comput. Phys. Commun.132 (2000) 306.

Chromaticity separation and the alpha response

Chromatic gratings can be uncomfortable to view and can evoke a large haemodynamic response. Both the discomfort and the amplitude of the haemodynamic response increase monotonically with the perceptual difference in the colour of the component bars of the grating, as registered by the separation in their chromaticity in the CIE 1976 UCS diagram. Individuals with photosensitive epilepsy exhibit epileptiform EEG activity in response to flickering light of alternate colours. The probability of the epileptiform response again increases monotonically with the separation of the colours in the CIE UCS diagram. We investigated whether alpha power, which is known to reflect the excitation of large populations of neurons, is similarly affected by the separation in chromaticity. Chromatic square-wave gratings with bars that differed in CIE UCS chromaticity were presented, together with a central fixation cross. In 18 non-clinical participants, alpha responses were recorded over the visual cortex (O1, Oz, O2, PO3, POz, PO4, P1, P2) and compared to responses in prefrontal cortex (F1, F2). Gratings comprised bars of two alternate colours that either had a small difference in chromaticity (mean CIE UCS separation of 0.03), a medium difference (mean separation of 0.19), or a large difference (mean separation of 0.43). The colour pairs had chromaticities that lay on the red-green, red-blue, or blue-green borders of the screen gamut. Regardless of the hue, the larger the separation in chromaticity, the greater the alpha desynchronization and the lower the alpha power (p = 0.004), but only in posterior electrodes (p < 0.001). Together this indicates that differences in colour evoke a cortical excitation that increases monotonically with the colour difference. In this respect the alpha response resembles the haemodynamic response.

On Achromatic Coloring of Corona Graphs

Let \(G = (V(G),E(G))\) be a simple graph and an achromatic coloring of \(G\) is a proper vertex coloring of \(G\) in which every pair of colors appears on at least one pair of adjacent vertices. The achromatic number of \(G\) denoted by \(\psi(G)\), is the greatest number of colors in an achromatic coloring of \(G\). In this paper, we find out the achromatic number for Corona graph of Cycle with Path graphs on the same order \(n\), Path with Cycle graphs on the same order \(n\), Path with Complete graphs on the same order \(n\), Path of order \(n\) with Star graph on order \(n+1\), Path with Wheel graphs on the same order \(n\) and Ladder graph with Path graph on the same order \(n\).

クレヨンの混同色解析と“混同色対指数”の提案

クレヨンの混同色解析と“混同色対指数”の提案

Efficient image decolorization with a multimodal contrast-preserving measure

Decolorization is widely used in monotonic displaying, black-and-white printing, single-channel image processing, and many computer vision applications. The conversion of a color image into a grayscale one suffers from data loss. This paper presents a novel parallel decolorization method which effectively preserves not only the spatially local color contrast but also the dominant non-local color contrast. A new multimodal contrast-preserving measure with a multimodal Gaussian distribution is proposed to relax the constraint of color contrast. The dominant non-local color pair set is constructed by taking advantage of a linear bounding volume hierarchy while the local color pair set is produced by removing duplicate instances of local color pairs. The whole pipeline design is highly parallel, allowing for a real-time GPU-based implementation. Experimental results and comparisons show that the proposed method can produce plausible decolorized images. A number of single-channel image processing applications, including edge detection, image segmentation, color augmentation, and image stylization, are demonstrated to verify the feasibility of the proposed decolorization method.

Food colour preference of hatchery-reared juveniles of African catfish Clarias gariepinus

Food colour preference is a fundamental aspect of food recognition and has practical application in the formulation of artificial diets and the design of visual baits. Food colour affects growth performance and feed efficiency in captive fishes. This study determined the food colour preference of the juveniles of the African catfish Clarias gariepinus under natural light in a roofed hatchery. A group of 20 juveniles were held in a transparent aquarium whose background colour was made white, blue, green, red, or black. The test food was diced shrimp flesh dyed blue, green, red, and yellow, with non-dyed natural flesh as the white control. In the food colour preference test, the catfish were presented the shrimp flesh in a pair of different colours at a time. The colour of the food that was first approached and ingested, i.e., the first response, was recorded. All the 10 possible food colour pairs were tested against five background colours. Quantitative analysis of the frequency of first response was done by χ2 test and Thurstone’s law of comparative judgment. The juveniles exhibited clear food colour preference that varied with the background colours. Against the black background, the first response was significantly biased to red shrimp flesh. Against the red and blue backgrounds, red and blue shrimp flesh were significantly preferred. Against the white and green backgrounds, no significant color preference was detected. Overall, juvenile African catfish preferred red and blue coloured shrimp flesh. This distinct preference for red and blue food could not be explained by associative learning (brown feed in the hatchery) and seemed innate.

Revisiting the weighting function for lightness in the CIEDE2000 colour‐difference formula

We have used 13 experimental datasets (7420 colour pairs) to study the performance of the weighting function for lightness proposed by the CIEDE2000 colour‐difference formula, because it has been suggested that this function can be improved by using the weighting function for lightness SL = 1 adopted by the CIE94 colour‐difference formula. Using the standardised residual sum of squares (STRESS) index, it was found that: (i) replacing the SL in CIEDE2000 with SL = 1 improved the results for 7/13 datasets considered, but the improvement was statistically significant only for 1/13 datasets; (ii) a Whittle‐type lightness‐difference formula can be used to replace the term ∆L*/SL in CIEDE2000, which led to a new colour‐difference formula with no statistically significant difference with respect to CIEDE2000 for any of the 13 experimental datasets. A modification of the CIEDE2000 formula using a Whittle‐type lightness formula is proposed.

Enhancement of low light level images using color-plus-mono dual camera.

In digital photography, the improvement of imaging quality in low light shooting is one of the users' needs. Unfortunately, conventional smartphone cameras that use a single, small image sensor cannot provide satisfactory quality in low light level images. A color-plus-mono dual camera that consists of two horizontally separate image sensors, which simultaneously captures both a color and mono image pair of the same scene, could be useful for improving the quality of low light level images. However, an incorrect image fusion between the color and mono image pair could also have negative effects, such as the introduction of severe visual artifacts in the fused images. This paper proposes a selective image fusion technique that applies an adaptive guided filter-based denoising and selective detail transfer to only those pixels deemed reliable with respect to binocular image fusion. We employ a dissimilarity measure and binocular just-noticeable-difference (BJND) analysis to identify unreliable pixels that are likely to cause visual artifacts during image fusion via joint color image denoising and detail transfer from the mono image. By constructing an experimental system of color-plus-mono camera, we demonstrate that the BJND-aware denoising and selective detail transfer is helpful in improving the image quality during low light shooting.

Pseudoachromatic and connected-pseudoachromatic indices of the complete graph

A completek-coloring of a graph G is a (not necessarily proper) k-coloring of the vertices of G, such that each pair of different colors appears in an edge. A complete k-coloring is also called connected, if each color class induces a connected subgraph of G. The pseudoachromatic index of a graph G, denoted by ψ′(G), is the largest k for which the line graph of G has a complete k-coloring. Analogously the connected-pseudoachromatic index of G, denoted by ψc′(G), is the largest k for which the line graph of G has a connected and complete k-coloring.In this paper we study these two parameters for the complete graph Kn. Our main contribution is to improve the linear lower bound for the connected pseudoachromatic index given by Abrams and Berman (2014) and provide an upper bound. These two bounds prove that for any integer n≥8 the order of ψc′(Kn) is n3/2.Related to the pseudoachromatic index we prove that for q a power of 2 and n=q2+q+1, ψ′(Kn) is at least q3+2q−3 which improves the bound q3+q given by Araujo et al. (2011).

Uniform Sampling of Subshifts of Finite Type on Grids and Trees

Let us color the vertices of the grid ℤd or the infinite regular tree 𝕋d, using a finite number of colors, with the constraint that some predefined pairs of colors are not allowed for adjacent vertices. The set of admissible colorings is called a nearest-neighbor subshift of finite type (SFT). We study “uniform” probability measures on SFT, with the motivation of having an insight into “typical” admissible configurations. We recall the known results on uniform measures on SFT on grids and we complete the picture by presenting some contributions to the description of uniform measures on SFT on 𝕋d. Then we focus on the problem of uniform random sampling of configurations of SFT. We propose a first method based on probabilistic cellular automata, which is valid under some restrictive conditions. Then we concentrate on the case of SFT on ℤ for which we propose several alternative sampling methods.

Kac’s ring: The case of four colours

We present an instance from nonequilibrium statistical mechanics which combines increase in entropy and finite Poincare recurrence time. The model we consider is a variation of the well-known Kac’s ring where we consider balls of four colours. As is known, Kac introduced this model where balls arranged between lattice sites, in each time step, move one step clockwise. The colour of the balls change as they cross marked sites. This very simple example rationalize the increase in entropy and recurrence. In our variation, the interesting quantity which counts the difference in the number of balls of different colours is shown to reduce to a set of linear equations if the probability of change of colour is symmetric among a pair of colours. The transfer matrix turns out to be non-Hermitian with real eigenvalues, leading to all colours being equally likely for long times, and a monotonically varying entropy. The new features appearing due to four colours is very instructive.