Applying colour science in colour design

Although colour science has been widely used in a variety of industries over the years, it has not been fully explored in the field of product design. This paper will initially introduce the three main application fields of colour science: colour specification, colour-difference evaluation and colour appearance modelling. By integrating these advanced colour technologies together with modern colour imaging devices such as display, camera, scanner and printer, some computer systems have been recently developed to assist designers for designing colour palettes through colour selection by means of a number of widely used colour order systems, for creating harmonised colour schemes via a categorical colour system, for generating emotion colours using various colour emotional scales and for facilitating colour naming via a colour-name library. All systems are also capable of providing accurate colour representation on displays and output to different imaging devices such as printers.     

Then and now: James Clerk Maxwell and colour

A survey of the researches of James Clerk Maxwell into the production and perception of colour is presented, and links to a selection of present day applications of colour science are indicated. Although false colour photography was not known in Maxwell's time, aspects of his work, suitably interpreted, have a bearing on the wide applicability of the technique. An outline is given of one application of false colour to visualising and analysing data on fluid motion.     

Investigation of Chinese skin colour and appearance for skin colour reproduction

A Chinese skin colour database is established based on measurements taken from nine bodies areas of 202 Chinese individuals to move towards accurate skin colour reproduction. The colour appearance of each skin point is predicted, and a comprehensive colour gamut for Chinese skin is determined. A consistent colour shift between facial and arm colours is identified, in which facial colour tends to be more reddish, more colourful, and darker than arm colour. Moreover, Chinese females are found to have lighter, paler, and more yellowish skin than Chinese males. Variations in Chinese skin colour are quantified, and body area differences and gender differences are shown to have significant effects on Chinese skin colour.     

Contemporary artists and colour: Meaning, organisation and understanding

What implications do the ranges of traditional and non-traditional media used by contemporary artists have for understanding the selection and specification of coloured materials? Interviews with prominent artists explore their use of colour and their views on the role of colour in their work. The paper establishes that the interview respondents operate successfully within a professional and permeable frame of reference, with different approaches to determination of colour meaning. The colour propositions of neuroscience, psychophysics and anthropological linguistics appear to have little impact on the respondents’ practice, and the paper concludes by suggesting the need to explore boundaries between disciplines.     

Transient colour centre in YAG : Nd

Formation of a transient absorption centre is demonstrated in YAG : Nd monocrystals on intensive irradiation in the near UV spectrum region. Spectral distribution has been studied of their absorption coefficient, their decay kinetics was also followed. Activation energy of the decay process was determined from the temperature dependence. The transient absorption centre possessing the character of V-centres exsrcise, in view of the spectral course of their absorption coefficient, a certain amount of influence upon the efficiency of the YAG : Nd laser.     

Supersymmetric strings and colour confinement

The (infinite-dimensional) supersymmetry algebra in 1 + 1 space-time dimension is extended in order to incorporate, in a non-trivial way, an internal symmetry. It turns out that this requirement implies that the internal symmetry is realized as a local gauge symmetry. Moreover, it is possible to construct string-like models with this underlying symmetry, where colour confinement is exactly realized as a consequence of the gauge constraints.     

Geometry and Elasticity of Strips and Flowers

We solve several problems that involve imposing metrics on surfaces. The problem of a strip with a linear metric gradient is formulated in terms of a Lagrangian similar to those used for spin systems. We are able to show that the low energy state of long strips is a twisted helical state like a telephone cord. We then extend the techniques used in this solution to two–dimensional sheets with more general metrics. We find evolution equations and show that when they are not singular, a surface is determined by knowledge of its metric, and the shape of the surface along one line. Finally, we provide numerical evidence by minimizing a suitable energy functional that once these evolution equations become singular, either the surface is not differentiable, or else the metric deviates from the target metric.     

Practical colour management

Spectrophotometers have been successfully used for colour measurement. This paper addresses digital imaging as a complementary and alternative method of colour measurement and appearance and an effective communication tool as part of a practical colour management programme within the supply chain of a textile retailer. The specific needs—to measure and communicate textured dyed material and printed fabric—are discussed, as well as the colour specification and quality control (QC) of currently un-measurable fabrics and accessories. A unique method of using digital imaging for the assessment of colour fastness will also be discussed.     

Asymmetric chiral colour

Chiral colour is considered in a general framework where the coupling constants associated with eachSU(3) component are allowed to be different. To reproduce QCD at low energy, gluons and axigluons cannot then be maximally mixed. Present data frome ⁺ e ^? colliders constrains the axigluon mass to values between 50 GeV and 375 GeV whilst the mixing angle is bounded by 13° and 45°. The lower limit of the axigluon mass is a definite bound at 90% C.L., whereas the upper limit only applies if chiral colour is to explain the anomalously high rates of hadron production at TRISTAN.     

Seeing in colour

Understanding perception of colour is challenging because what we see is not always what is there, which is a phenomenon we call illusions. Here we review the nature of colour vision, and the problems facing most current models and explanations. Focusing on our recent research on humans, bees and computers, we describe a new, more ecologically based explanation that provides a clear framework for why we see what we do.     

Generalised leptonic colour

It is conceivable that there is an SU?_(N)$\mathit{SU}{(N)}_{?}$ ‘colour’ gauge group for leptons, analogous to the gauged SUq₍₃₎$\mathit{SU}{(3)}_q$ colour group of the quarks. The standard model emerges as the low energy effective theory when the leptonic colour is spontaneously broken. The simplest such generalised leptonic colour models are constructed. We show that the see-saw mechanism for small neutrino masses, along with the theoretical constraint of electric charge quantisation, suggests that the models with N=3$N=3$, 5, 7 are the theoretically most promising cases. A striking feature of generalised leptonic colour is the physics associated with the extra leptonic degrees of freedom—the liptons. These particles can potentially be discovered at future colliders, such as the LHC, making the idea testable in the near future.     

Spontaneous colour confinement

The long-range order of the confinement phase of QCD is characterized by a macroscopic field (order parameter) transforming as a general Lorentz symmetric tensor, and as a (8, 8) representation of the SU(3)×SU(3) group. The resulting Ginzburg-Landau chromodynamics has the condensate vacuum behaving like a Lorentz-invariant dual colour superconductor capable of describing the spontaneous formation of the colourless domains (hadrons) immersed in the confining medium.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday.It gives me much pleasure to express my gratitude to Professor Votruba for introducing me into his beloved field of elementary-particle physics, and for a great number of pleasant and informative discussions.     

Broken colour symmetry and liberated quarks

We present and discuss a quark model of hadrons, in which local SU(3) gauge symmetry is completely broken and yet asymptotic freedom is presented. There is no infrared slavery in this model, and isolated quarks are free to exist. Colour becomes a global symmetry which is only approximate under SU(3) but nearly exact under SU(2) × U(1), as far as the usual hadron spectroscopy is concerned.     

Nonperturbative QCD vacuum and colour superconductivity

We discuss the possibility of existence of colour superconducting state in real QCD vacuum with nonzero _sGG. We argue, that nonperturbative gluonic fields might play a crucial role in colour superconductivity scenario.     

Quarkonium suppression: Gluonic dissociation vs. colour screening

We evaluate the suppressionof J/ψ production in an equilibrating quark gluon plasma for two competing mechanisms: Debye screening of colour interaction and dissociation due to energetic gluons. Results are obtained for S + S and Au + Au collisions at RHIC and LHC energies. At RHIC energies the gluonic dissociation of the charmonium is found to be equally important for both the systems while the screening of the interaction plays a significant role only for the larger systems. At LHC energies the Debye mechanism is found to dominate both the systems. While considering the suppression of directly produced T at LHC energies, we find that only the gluonic dissociation mechanism comes into play for the initial conditions taken from the self screened parton cascade model in these studies.     

Elliptic Flowers: New Types of Dynamics to Study Classical and Quantum Chaos

We construct examples of billiards where two chaotic flows are moving in opposite directions around a non-chaotic core or vice versa; the dynamics in the core are chaotic but flows that are moving in opposite directions around it are non-chaotic. These examples belong to a new class of dynamical systems called elliptic flowers billiards. Such systems demonstrate a variety of new behaviors which have never been observed or predicted to exist. Elliptic flowers billiards, where a chaotic (non-chaotic) core coexists with the same (chaotic/non-chaotic) type of dynamics in flows were recently constructed. Therefore, all four possible types of coexisting dynamics in the core and tracks are detected. However, it is just the beginning of studies of elliptic flowers billiards, which have already extended the imagination of what may happen in phase spaces of nonlinear systems. We outline some further directions of investigation of elliptic flowers billiards, which may bring new insights into our understanding of classical and quantum dynamics in nonlinear systems.     

Two international colour meetings

Two international Colour meetings held in May 1961 have given an opportunity or scientists working in this field to meet and compare notes. The first was the Maxwell Colour Centenary in London, organized by the Colour Group, with the Institute of Physics and Physical Society, and the Jnter–Society Colour Council (of the U.S.A.), to celebrate the first demonstration of colour photography; it was deliberately kept informal as its primary purpose was an Anglo–American get-together, and its twenty–odd invited papers consisted mostly of reviews of progress in the field over the last hundred years. The second meeting was on a larger scale, held in Dusseldorf, and organized jointly by the Fachnormenausschuss Farbe im Deutschen Normenausschuss (FNF) and the Centre d'Jnformation de la Couleur (C.I.C.) of France, being the fifth in a series of JournCes Jnternationales de la Couleur. More than eighty papers covered a range of topics from colorimetry and colour vision to problems of education and the use of colour in fashion, decoration, and advertising.     

Simple coherent-optical colour encoder

A simple, coherent-optical processor for the production of colour-encoded images from half-tone screened, black and white transparencies is described. Only one laser is used, and the images generated when different diffracted orders and selected by a spatial filter are picked up by a black and white, closed-circuit television system. The screen of the monitor is photographed successively through appropriate coloured filters to produce a colour-encoded image.     

Hadron diffractive processes: the structure of soft pomeron and colour screening

On the basis of the experimental data on diffractive processes in πp, pp and pˉp collisions at intermediate, moderately high and high energies, we restore the scattering amplitude related to the t-channel exchange by vacuum quantum numbers by taking account of the diffractive s-channel rescatterings. At intermediate and moderately high energies, the t-channel exchange amplitude turns, with a good accuracy, into an effective pomeron which renders the results of the additive quark model. At superhigh energies the scattering amplitude provides a Froissart-type behaviour, with an asymptotic universality of cross sections such as σ^tot _πp/σ^tot _pp→ 1 at s→∞. The quark structure of hadrons being taken into account at the level of constituent quarks, the cross sections of pion and proton (antiproton) in the impact parameter space of quarks, σ_π(r _1⊥, r _2⊥; s) and σ_p(r _1⊥, r _2⊥, r _3⊥; s), are found as functions of s. These cross sections implicate the phenomenon of colour screening: they tend to zero at |r _i⊥−r _k⊥|→ 0. The effective colour screening radius for pion (proton) is found for different s. The predictions for the diffractive cross sections at superhigh energies are presented. Received: 15 December 1998     

Meson exchange interactions at low and intermediate energies: colour screening effects

We consider the colour screening effects of constituent quarks and the exchange of effective gluons in the interaction of hadrons. To this end we propose two different processes derived from fundamental properties of the underlying microscopic theory (QCD). Sum rules for diagrams providing colour screening are also given.