bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toward a more accurate and extensible colorimetry. Part Ii. Discussion
Authors: Thornton William A. 
Published: June 2007

AbstractTechnical advances in the forty years since the Stiles‐Burch color‐matching work‐among them the bright split‐field visual colorimeter coupled by quartz light pipe to a spectroradiometer‐allow measurement of an accurate absolute spectral power distribution (SPD) of every viewed light. Furthermore, the ability to measure accurately the power‐content of each spectral constituent of a viewed light has clarified both colorimetric procedures and signficance, for example, of color‐matching functions (CMFs) and tristimulus values. Three disparate sets of three spectral primaries were used throughout the work. This has not been done before, and its use elucidated much of the difficulty (as described by Judd, Stiles, MacAdam, Wyszecki, and others) inherent in traditional colorimetry. Errors in computed chromaticities of sets of 28 visually‐matching lights depend strongly on their spectral content, and are particularly large in the presence of high spectral content in the violet, deep red, and near 500 nm or 580 nm. Peaks of visual efficiency, and minima in chromaticity errors, were found with power in three intermediate spectral regions near 450 nm, 530 nm, and 610 nm. Computed luminance (1964 CIE Standard Observer) and power‐content also depend strongly on spectral content of the visually‐matching white lights. That this is true of luminance is generally unknown. Perceived brightness of single spectral lights in isolation, and of mixtures, was examined at length: As a rule, removing one spectral component from a mixture increases perceived brightness, thus invalidating both luminance and R + G + B as correlates of brightness. Visual tests of the Grassmann proportionality and additivity assumptions, with highly metameric mixtures, tended to confirm them. Nevertheless, numerous tests‐substituting pairs of actual visually‐matching lights from one primary‐set for pairs from another, which is how “transformation of primaries” is (mathematically) carried out‐led to the inescapable conclusion that the normal human visual system does not honor such transformation. At the same time, numerous indications supported a particular set of primaries as an invariant of the visual system, making transformation needless as well as invalid. Chromaticity errors are not the fault of the particular maximum‐saturation CMFs utilized; the observer's own CMFs do no better, whatever the primary‐set. Soundness of traditional construction of the chromaticity diagram is shown to depend on the primary‐set, breakdown occurring for some otherwise legitimate primary‐sets.
Estimation equations for practical use on lightness‐reflectance (L/Y) ratios in the whole chromaticity gamut
Authors: Nayatani Yoshinobu , Ihara Masamori , Sobagaki Hiroaki , Hashimoto Kenjiro 
Published: June 2007

AbstractA multiple regression analysis is reported to predict L/Y ratios as a function of chromaticity coordinates x, y. the specified variables were selected statistically from the 20 terms of Ψmψn. the quantities Ψ, ψ are the transformed values of x, y, respectively, and 1 ≦ m + n ≦ 5. the contour lines of equal L/Y ratios are estimated in the whole chromaticity gamut including spectral colors by using each of the regression equations with 6, 9, and 20 specified variables. the regression equations with 20 specified variables can satisfactorily predict the corresponding experimental results. In case of regression equations with 6 specified variables, the predicted contour lines are significantly different in shape from those of the corresponding experiments. the same defects are found in the Ware‐Cowan equation only using 4 specified variables recommended by CIE Division 1 for further tests.
NCS and DIN notations for the OSA‐UCS atlas samples
Authors: Smith N. S. , Whitfield T. W. A. , Wiltshire T. J. 
Published: June 2007

AbstractNCS (C/1931) and DIN (C/1931 and D65/1964) notations of the 558 OSA‐UCS atlas samples are presented in two tables. One table provides the NCS and DIN notations for the 424 regular samples; the other for the 134 near‐neutral (half‐step) samples.
Estimation of film thickness nonuniformity effects on coating optical properties
Authors: Bierwagen Gordon P. 
Published: June 2007

AbstractFilm nonuniformities cause many problems for the coating scientist. One area of coating film performance that they impact directly is optical properties. Measurements and predictions of film optical performance are all made assuming uniform film thickness. Incomplete leveling and other film application problems often yield nonuniform films with significant film thickness fluctuations. These film thickness imperfections can be modeled by a sine wave thickness fluctuation, and this fluctuation can be used to estimate the effects of nonuniformity in thickness on optical properties. This has been done using both approximate equations for scattering, transmission, and reflectance in films (zero absorption) and for the Kubelka‐Munk equations including absorption. the effects of average film thickness and amplitude of fluctuation on measured S, R, and T values are predicted numerically for several cases of [K, S] pairs consistent with wavelength independent situations (white or similar films) over black substrates, and then the calculations are used to consider colored films [considering δE(L*a*b*)] over black substrates. Film thickness fluctuations are shown to have considerable impact on film optical properties, especially in thin highly scattering films. Examples of the types of predictions that can be made are given; how the results depend on the coating optical parameters is also shown.
Techniques for simulating object color under changing illuminant conditions on electronic displays
Authors: Troost Jimmy M. , De Weert Charles M. M. 
Published: June 2007

AbstractWe compare several computational schemes that can be used for the simulation of object colors under changing illuminant conditions on electronic displays. These schemes differ in the assumptions that are made concerning illuminant invariant quantities, and the amount of a priori information that is required. This latter feature is especially important for computer graphics applications and theoretical color constancy research because in many instances information about illuminant and object characteristics is minimal. A large set of tristimulus values of Munsell papers, as defined under CIE Standard Illuminant C, served as input data. Next, illuminant invariant quantities were obtained for each computational scheme that were used to predict x, y chromaticity coordinates and relative luminosity Y under nine different phases of daylight, varying from 4000 K to 20000 K. It was found that the differences between so‐called reflectance models on the one hand, and theoretically less accurate tristimulus ratio models on the other, are small and in most cases within three MacAdam units of color difference ≈1 JND).
Color correction using principal components
Authors: Vrhel M. J. , Trussell H. J. 
Published: June 2007

AbstractThe problem of color correction for changes in illumination is briefly reviewed. A new method using the spectral reflectance distribution in the image is introduced and compared to a white‐point mapping method. The new method is based on principal component analysis and thus is dependent upon the characteristics of the images that are to be viewed. These two methods are compared using chromaticity plots and the CIE L*a*b* ΔE measurement, for test samples which include color copiers, thermal writers, ink‐jet printers, and lithography.
Application of some statistical methods for comparing samples of Hue‐Angle data
Authors: Chronicle Endward , Nimmo‐Smith Ian 
Published: June 2007

AbstractSeveral color spaces utilize angular measures of hue:for example, CIE 1976 u, v hue‐angle; CIE 1976 a, b hueangle. Such measures are not amenable to conventional statistical analysis, unless a categorization of hue‐angles has previously been decided upon, in which case nonparametric tests are appropriate. In this article we present two recently established methods that are appropriate for the parametric statistical analysis of hue‐angle data from two or more samples: [i] a test of the equality of angular variances; [ii] a test of the equality of mean angles. These tests may be performed easily on a microcomputer and produce statistics conforming approximately to well known distributions. We envisage that the tests will be of interest to psychologists and others working in the field of color research. © 1992 John Wiley & Sons, Inc.
Numerical methods for colorimetric calculations: Sampling density requirements
Authors: Smith Brent , Spiekermann Charles , Sember Robert 
Published: June 2007

AbstractThis article quantifies errors arising from various integration methods and from sampling density in the numerical estimation of colorimetric integrals, e.g., tristimulus values. Both data sampling density and various numerical integration method errors will be distinguished. A test is presented to quantify sampling interval requirements for accurate colorimetric calculations for various illuminants. © 1992 John Wiley & Sons, Inc.
The primary hue circle
Authors: McCamy C. S. 
Published: June 2007

AbstractMunsell started to base his color‐order system on measured physical quantities, but it came to represent the order of colors us they ure perceived. The hue circle represents fundamental facts about color vision. The Munsell hue circle has anomalous placement of blue and the use ($five principal hues does not relate to color vision nor applied color science. A reoriented hue circle, labeled with the additive and subtractive primariesblue,green, red, yellow, magentu, and cyan‐but retaining the existing Munsell hue spacing and sectors is proposed.The primury hue circle relates to vision and color‐reproduction processes, so it should exert a unifying influence on color .science. 0 1993 John Wi1ey . & Sons. Inc..
Quantifying colour appearance. part III. Supplementary LUTCHI colour appearance data
Authors: Luo M. Ronnier , Gao X. Wang , Rhodes Peter A. , Xin H. John , Clarke Anthony A. , Scrivener Stephen A. R. 
Published: June 2007

AbstractThe experimental data from this study supplements the LUTCHI Colour Appearance Data as described in Part I of this paper. Two further experiments were carried out: one was to check conflicting results found previously, and another was to extend the range of luminance conditions used earlier. In addition, a brightness attribute was added to the original lightness, colourfulness, and hue scales for colour assessment. Experiment I results verified the uncertainties found previously in the comparison between luminous and nonluminous colours, and between the grey background results with and without a white border. Experiment II results revealed the changes in four perceived attributes under six quite different adapting luminances. The results were then used to test five uniform colour spaces and colour‐appearance models used in Part II of this paper. Hunt's 91 model gave more accurate predictions of the experimental visual results, in comparison with the other spaces and models. Its predictive error for all attributes studied is within the accuracy of the typical observer.
Illuminance dependency of equivalent lightness on chromatic object colors
Authors: Nayatani Yoshinobu , Sobagaki Hiroaki , Hashimoto Kenjiro 
Published: June 2007

AbstractStudy of the equivalent lightness of chromatic object colors was reported by Ikeda et al. and Yujiri from the scotopic to the photopic illuminance range. In the photopic range, the results showed the dependence on the adapting illuminance to the Helmholtz‐Kohlrausch effect [the L/Y (lightness/luminance factor) ratio effect]. The model for predicting the perceived lightness of chromatic object colors proposed by the present authors has been modified to take into account the effect of the change of adapting illuminance. By use of the modified model by the present authors and the method for estimation of the equivalent lightness in the mesopic range by Ikeda et al., the equivalent lightness of object colors with five principal Munsell Hues and with various Munsell Chromas were estimated, for comparison with the results observed by Yujiri from 0.02 to 3000 lx.
Surface color and color constancy
Authors: Petrov A. P. 
Published: June 2007

AbstractColor constancy is often treated as the tendency of surfaces to stay the same perceived color under changing illumination or context (removing/adding/replacing surrounding objects). But these types of color constancies are not basic ones and there is another kind of color constancy that is fundamental for the explanation of all color constancy phenomena. We experience it when looking at a curved uniformly colored surface or when changing the shape of the surface. A new concept of surface color is developed and the variety of all perceived colors is suggested to be described as a nine‐dimensional set of 3 X 3 matrices corresponding to different surface colors. Examples of color matrices calculated for some colored surfaces being viewed by the standard viewer are presented and arguments supporting the concept are discussed. It is shown that the set of color matrices represents all perceived colors quite adequately.
CRT colorimetry. part I: Theory and practice
Authors: Berns Roy S. , Motta Ricardo J. , Gorzynski Mark E. 
Published: June 2007

AbstractThe relationship was derived for computer‐controlled color CRT displays between spectral radiant exitance emitted and digital counts. The derivation was historical and could be traced to pioneering work in photographic sensitometry, vacuum tube physics, and broadcast television. By performing radiometric measurements relative to a display's maximum exitance, the model simplified to a two‐stage model. The first stage was a nonlinear transformation relating normalized digital‐to‐analog converter values to device‐dependent monitor tristimulus values using model parameters of gain, offset, and γ. The second stage was a linear transformation where the device‐dependent monitor tristimulus values were transformed to device‐independent CIE tristimulus values. By using the model, colorimetric characterization accuracy of better than 0.5 CIELAB color‐difference units for 125 colors sampling the display color gamut was achieved by measuring the CIE tristimulus values of only eight colors. The model had equivalent performance to methods using extensive measurements and table lookup. © 1993 John Wiley & Sons, Inc.
Age‐related changes in the color appearance of broadband surfaces
Authors: Schefrin Brooke E. , Werner John S. 
Published: June 2007

AbstractChromatic and achromatic components of 15 broadband surfaces were scaled by 15 younger (mean age = 21.3 yrs) and 15 older (mean age = 71.9 yrs) subjects. Colored surfaces were obtained from the OSA Uniform Color Scales and presented as 2°‐diameter test stimuli that were freely viewed. Stimuli were presented in a grey (L = 0) ganzfeld‐like hemisphere with an illuminant having a correlated color temperature of 6200 K. Five stimuli were presented at three lightness levels (L = −4, 0 and +4). Each lightness level included samples chosen so that one pair plotted approximately along a tritan axis in MacLeod‐Boynton receptor‐excitation space and another pair plotted on an axis of constant S‐cone stimulation. The appearance of each test stimulus was scaled using the hue terms red, green, yellow and blue, and in terms of the proportion of overall chromatic content. The results indicate that hue names were used similarly for the two groups of subjects, however, older subjects perceived all stimuli as having less chromatic content than demonstrated by younger observers. Differences between the two age groups in perceived chromatic content of the test stimuli progressively increased as the lightness and luminance levels of the test stimuli decreased. Results obtained from control experiments suggest that this difference between the two age groups is not due to the influence of senile miosis or lenticular senescence leading to variations in the illuminances and spectral compositions of the test lights reaching the retina. © 1993 John Wiley & Sons, Inc.
Spatial integration properties in vision with chromatic stimuli
Authors: Kawabata Yasuhiro 
Published: June 2007

AbstractThe present study showed that (1) the critical area of spatial integration was larger for equiluminous chromatic stimuli than for luminance stimuli, and that (2) the critical area became smaller as the chromatic saturation of the adaptation field was increased. The latter suggests that the chromatic coding systems, which are assumed to posses poorer spatial resolution or larger spatial integration than the luminance system, could change their spatial integrating organization independently of the luminance system which could also change its own spatial organization. © 1993 John Wiley & Sons, Inc.
Successive‐ganzfeld haploscopic viewing technique for color‐appearance research
Authors: Fairchild Mark D. , Pirrotta Elizabeth , Kim Taek 
Published: June 2007

AbstractA new experimental technique for color appearance research is described. This technique, successive‐Ganzfeld haploscopic viewing, combines advantages of traditional haploscopic and successive‐haploscopic techniques with modifications that provide a more amenable viewing situation for the observer. This note reviews the need for haploscopic viewing techniques in color appearance research and the pros and cons of traditional techniques. and outlines the implementation of the new technique along with current and potential applications.
Existence of two kinds of representations of the helmholtz‐kohlrausch effect. I. the experimental confirmation
Authors: Nayatani Yoshinobu , Sobagaki Hiroaki , Hashimoto Kenjiro 
Published: June 2007

AbstractIn the representation of the Helmholtz‐Kohlrausch effect, a new method (the VCC method using variable chromatic colors) is proposed in addition to the method used so far (the VAC method using variable achromatic colors). The new VCC method showed a significantly larger Helmholtz‐Kohlrausch effect than the VAC method previously used. For practical applications, the results by the VCC method are more effective than the VAC method. Three kinds of experiments are reported for clarifying the difference in effect between the two methods. © 1994 John Wiley & Sons, Inc.
Existence of two kinds of representations of the helmholtz‐kohlrausch effect. II. the models
Authors: Nayatani Yoshinobu , Sobagaki Hiroaki , Hashimoto Kenjiro 
Published: June 2007

AbstractA formulation for predicting the Helmholtz‐Kohlrausch (H‐K) effect is given to the new VCC (variable chromatic color) method, which can derive the luminance factors of various chromatic object colors that match in perceived lightness with a fixed achromatic color. By using the formulation, the H‐K effect by the VCC method is predicted within the whole chromaticity gamut including spectral colors. the magnitude of the effect in logarithmic scale by the VCC method is estimated to be twice as large as that by the VAC (variable achromatic color) method previously used. It is also stated that the VCC method is practically more important than the VAC method. the effectiveness of the new formulation is confirmed by comparing its predictions with the observations in two kinds of experiments. © 1994 John Wiley & Sons. Inc.
Some reflections on studying colour combinations
Authors: Sivik Lars , Hård Anders 
Published: June 2007

AbstractThis article opens with a critical discussion of “laws of colour harmony,” which is followed by an examination of the diverse theoretical and empirical foundations for the relatively common concept “complementary colours.” Using the perceptual NCS‐system for colour description as a basis, the authors have outlined a colour combination model, which is described briefly here. © 1994 John Wiley & Sons, Inc.
Luminescent pigments in security applications
Authors: Becidyan A. Nurhan 
Published: June 2007

AbstractPapers and any printable surface that have value are subject to forgeries. Various methods of security printing are identified and utilizing luminescent pigments as security items are discussed. Problems with classical luminescent pigments because of toxicity and particle size are identified. A new range of luminescent pigments that are either excited by UV or IR are presented and their chemical and physical characteristics defined. Also samples from actual security applications are given. © 1995 John Wiley & Sons. Inc.
Colorimetric evaluation of daylight simulator sources
Authors: Hisdal Bjarne 
Published: June 2007

AbstractThe color shift of a sample due to a change in illuminant can be expressed either in terms of the CIE General Color Rendering Index, Ra, based on the average for eight color samples, or in terms of the CIE Metamerism Index MIvis, the average for five pairs (or couples) of samples. It is shown that, in an ideal case where the eight samples constitute four complementary pairs, the value of the average for eight can be predicted accurately from the average for only four of the eight samples. This is approximately also the case for a prediction based on four of the actual eight CIE samples, but in this case there is some uncertainty in the predicted Ra values. For MIvis, a useful approximation in value can be obtained using only two of the five defined couples. Finally, it is shown that Ra and MIvis evaluate illuminants in largely the same way.
Sensitivity differences in Chroma, Hue, and Lightness from several classical threshold datasets
Authors: Melgosa M. , Hita E. , Pérez M. M. , El Moraghi A. 
Published: June 2007

AbstractA check of the weighting functions proposed by the CIE Technical Committee 1‐29 (TC1‐29) [Color Res. Appl. 18, 137–139 (1993)] has been carried out using pairs of samples with only a threshold difference in chroma, hue, or lightness. Experimental results with object and aperture colors were used and some parametric factors can be appointed: the dependence of ΔC* on C* appears to be about two times stronger for related color versus the aperture color mode; and the ΔH* dependence on C*, weak but significant for related colors, becomes insignificant for aperture colors. the hue‐angle dependences of ΔH* after correction for C* and the dependences of ΔL* on L* or C* are found not significant for aperture colors. After normalization of the five different datasets employed, the results achieved are in overall good agreement and support the proposal of the CIE TC1‐29.
Determination of constant Hue Loci for a CRT gamut and their predictions using color appearance spaces
Authors: Hung Po‐Chieh , Berns Roy S. 
Published: June 2007

AbstractA colorimetrically characterized computer‐controlled CRT display was used to determine 24 loci of constant perceived hue for pseudo‐object related stimuli, sampling the display's interior color gamut at constant lightness and the edge of its gamut at variable lightness. Nine observers performed three replications generating matching data at 132 positions. the constant hue loci were used to evaluate the correlation between perceived hue and hue angle of CIELAB, CIELUV, Hunt, and Nayatani color appearance spaces. the CIELAB, CIELUV, and Hunt spaces exhibited large errors in the region of the blue CRT primary, while the Nayatani and CIELUV spaces produced large errors in the region of the red primary for constant lightness stimuli. Along the edge of the CRT's color gamut (variable lightness stimuli), all the spaces had a similar trend, large errors in the cyan region. the differences in performance between the four spaces were not statistically significant for the constant lightness stimuli. For the variable lightness stimuli, CIELAB and CIELUV had statistically superior performance in comparison with the Nayatani space and equal performance in comparison with the Hunt space. It was concluded that for imaging applications, a new color appearance space needs to be developed that will produce small hue error artifacts when used for gamut mapping along loci of constant hue angle. © 1995 John Wiley & Sons, Inc.