ISSN:0361-2317    

DOI:10.1002/col.5080160102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0361-2317    

DOI:10.1002/col.5080160103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractConventional mechanisms for computer colorant formulation commonly employ the Kubelka‐Munk theory to relate reflectance values to colorant concentrations. However, there are situations where this approach is not applicable and hence an alternative is desirable. One such method is to utilize artificial intelligence techniques to mimic the behavior of the professional colorist. The purpose of this paper is to describe recent research being carried out at Reading University, sponsored by Courtaulds Research, that utilizes collections of cellular automata, known as neural networks, in the problem of recipe predictio

ISSN:0361-2317    

DOI:10.1002/col.5080160104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA heterochromatic brightness or lightness match, established at photopic levels, is not expected to hold at lower adapting luminances. This applies, in particular, to the Purkinje Effect, concerning the red‐blue comparison. The fact that a “blue” stimulus mainly involves the shorter wavelengths favors the interpretation in terms of rod intrusion, coming gradually into play as the eye, pre‐adapted to a photopic level, is becoming adapted to a mesopic or scotopic one. The two experiments described in this paper aim to put into evidence some effects that are likely to be due to postreceptoral mechanisms, and which may confuse the student faced with a practical demonstration of the Purkinje Effect. In particular, we consider the blue lightness enhancement after an abrupt decrease in adapting luminance, and the decay of lightness‐luminance discrepancy of narrow‐band stimuli during the reco

ISSN:0361-2317    

DOI:10.1002/col.5080160105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA hypothesis is proposed to predict the perceived lightness of chromatic object colors, which is well known as the Helmholtz‐Kohlrausch effect or the lightness‐reflectance ratio effect (L/Yeffect). The hypothesis is, “When two chromatic object colors with different hues have the same values for each of three attributes (whiteness, blackness, and chromaticness), the two colors have the same perceived lightness, including a chromatic‐component contribution.” The hypothesis is tested by two kinds of experiments: perceivedlightness matching using the NCS Color Atlas, and chromatic tiles determined by Wyszecki. Both results strongly confirm the hypothesis. Further, contour lines of constantL/Yratios are estimated, and are very similar to those reported p

ISSN:0361-2317    

DOI:10.1002/col.5080160106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThere are two common chromaticity standards for video‐display‐unit reference white, one standard at 6500 K correlated color temperature (CCT), called D65 for short, and the other, an industrial standard, at 9300 K CCT. The choice of D65 evolved from the NTSC specification for television receivers based on Illuminant C—an average daylight at 6800 K CCT. Although originally the studio illumination was much redder than D65, modern television cameras operate in daylight, so a daylight white standard is most likely to allow exact color reproduction at the receiver. Hence average daylight is the most natural white point. However, many manufacturers chose 9300 K because the chromatic efficiency of the prevailing blue phosphors was greater than that of red or green phosphors, because viewers did not object to a blue color bias, and because 9300 K was bluer than any of the prevailing ambient illuminations. In the years since the adoption of the 9300‐K standard, these facts underwent some change, and also VDUs came to be used for graphics as well as for television. This paper outlines the reference‐white problem, and suggests a reevaluation of the 9300

ISSN:0361-2317    

DOI:10.1002/col.5080160107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA vector‐space approach to color systems has been shown to be useful in describing metameric effects and producing metamers under different illuminations. The vector‐space approach has also been used to describe color scanning and reproduction systems. This article extends the applications presented in previous work by introducing set theoretic concepts which allow the addition of realistic constraints. The set theoretic methods allow the full range of solutions of color problems to be explored by allowing a set of solutions to a particular problem formulation. The applications discussed here include producing realizable metamers and the design of scanning filt

ISSN:0361-2317    

DOI:10.1002/col.5080160108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractFirst, methods to define the region of colors indistinguishable from a standard color are reviewed, both for aperture and surface colors. Then, an algorithm to define discrimination ellipsoids for surface colors in (x,y,l) space is described, where1is a function ofY.The data are a set ofPi, the proportion that a comparison stimulussiis judged discriminable from a standard stimulusSo(the method of constant stimuli). An ellipsoid is defined aroundSosuch that, if the distance betweenSoandsiis evaluated by the radius of the ellipsoid in that direction, then that distance is related toPiin the form of a sigmoid curve (the cumulative normal distribution). The third axis of the ellipsoid is defined to be parallel with theYaxis and hence there are four free parameters. These parameters are estimated using the principles of either chi‐square minimum or maximum likelihood estimation. The algorithm was applied to the data obtained from, respectively, R.M. Rich, D.C. Rich, and Witt and Döring. Results by the present method were compared with their results, which were obtained using different procedures. The method was also applied to the data of Bartleson to test the possibility that the domain of colors called “brown” is ellipsoidal in form; the result was negative. A theoretical discussion on the naure of the sigmoid curve is in

ISSN:0361-2317    

DOI:10.1002/col.5080160109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0361-2317    

DOI:10.1002/col.5080160110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0361-2317    

DOI:10.1002/col.5080160111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY