Color Research & Application

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Online ISSN: 1520-6378
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Article
The purposes of this study were to measure areas of complete spatial summation (i.e., Ricco's area) for S- and L-cone mechanisms and to evaluate whether the sizes of Ricco's area could be explained in terms of either the densities of photoreceptors or ganglion cells. Increment thresholds were measured at the fovea and at 1.5°, 4°, 8°, and 20° in the superior retina using a temporal two-alternative forced-choice procedure. Test stimuli ranging from -0.36 to 4.61 log area (min(2)) were presented on concentric 12.3° adapting and auxiliary fields, which isolated either an S- or L-cone mechanism on the plateau of the respective threshold vs. intensity function. The data indicate that from 0-20° retinal eccentricity, the size of Ricco's area is larger for the S-cone mechanism than the L-cone mechanism, increases monotonically for the L-cone mechanism, and, for both cone mechanisms, increases between 8-20° retinal eccentricity. This latter finding suggests that ganglion cell density rather than cone density defines the size of Ricco's area in the parafoveal and peripheral retina.
 
Article
Colour constancy assessed by asymmetric simultaneous colour matching usually reveals limited levels of performance in the unadapted eye. Yet observers can readily discriminate illuminant changes on a scene from changes in the spectral reflectances of the surfaces making up the scene. This ability is probably based on judgements of relational colour constancy, in turn based on the physical stability of spatial ratios of cone excitations under illuminant changes. Evidence is presented suggesting that the ability to detect violations in relational colour constancy depends on temporal transient cues. Because colour constancy and relational colour constancy are closely connected, it should be possible to improve estimates of colour constancy by introducing similar transient cues into the matching task. To test this hypothesis, an experiment was performed in which observers made surface-colour matches between patterns presented in the same position in an alternating sequence with period 2 s or, as a control, presented simultaneously, side-by-side. The degree of constancy was significantly higher for sequential presentation, reaching 87% for matches averaged over 20 observers. Temporal cues may offer a useful source of information for making colour-constancy judgements.
 
Article
The goal of our study was to evaluate colour vision during high-altitude mountain climbing without supplemental oxygen. Two Himalayan expeditions were invited to test their colour perception at both the highest possible altitude and on the largest possible number of subjects. The panel desaturated D15 was used, because only a simple test could be transported to those altitudes. There were 2 evaluations (i.e., 4 eyes) at 7,000 m during the first expedition in 1997, and 3 evaluations (i.e., 6 eyes) at 6,500 m during the second expedition in 1998. The results were in perfect agreement and can be considered practically normal for all 5 mountain climbers.
 
Article
Threshold vs. intensity (tvi) functions were measured under conditions in which the slope of the rising branch approximated the deVries-Rose law in order to evaluate the contribution of intrinsic visual noise (dark light, Eigengrau) to age-related elevations in threshold under photopic conditions. Data were obtained from 48 observers (20-88 years) using a temporal 2AFC procedure. The stimulus was centered at 8° nasal retinal eccentricity and consisted of a 560 nm, 14.4' test flash (10 ms) concentric with a steady 500 nm (12.9°) adapting field (13 intensity levels ranging from 0-9 log quanta · sec(-1) · deg(-2)), which resulted in clear scotopic and photopic branches. Photopic thresholds increased linearly with age at a rate of 0.08 log unit per decade at the cornea. The mean slope of the rising portion of the tvi functions (in log-log coordinates) was 0.62, and not correlated with age. Dark light values increased with age, but not significantly. Dark light was a statistically significant predictor of individual differences in absolute photopic threshold, but it is not responsible for age-related increases in threshold under photopic conditions.
 
Article
Conditions under which a computational procedure can be applied to arbitrary camera sensors to permit estimation of the human photoreceptor response are considered. The adopted procedures recover the effective surface reflectance at the time of measurement, and the reflectance estimates depend not only on the surface, but upon the viewing geometry. The present method for color rendering assumes that the observer's state of adaptation at the time of viewing the original and the rendered images is the same. The analysis aids in specifying which classes of surfaces are required to be accurately rendered, and for which surfaces some error can be tolerated.
 
Article
Bright strongly metameric visually matching pairs of white lights are studied. Generally, one member of the pair is a constant broadband reference white, in accordance with the Maxwell method. Spectral compositions of the other member are chosen from eight types found in Parts I, II, and III to lead to trismulus errors, over a large range of magnitude, by the 1964 CIE Standard Observer. Field luminance has been tripled over that of the earlier work to the order of 100 cd/m2, the range of typical industrial color-matching. Experiments with visual fields of 1.3° have been added. Tristimulus errors in computations by the appropriate CIE Standard Observer, at the higher brightness levels, and at visual field sizes of both 10° and 1.3°, are as large as those found in the earlier work with dimmer 10° fields. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 189–198, May 1997
 
EDX microanalysis results of the different decorations.
Article
The metallic luster of glazed ceramics is a very special type of decoration. Its optical properties are characterized by a change of colour according to the observation conditions. In diffuse light, these decorations are often green, brown, or ochre-yellow. In specular reflection, they show an associated coloured metallic reflection (blue, golden-yellow, orange, etc.). Metallic copper and/or silver colloids almost always compose the metallic luster decorations. We wish to define the role of these two metals in the colouration observed both in diffuse light and in specular reflection. Our investigations show that a relationship exists between the proportions of copper and silver, and the diffuse colour. The green decorations contain more silver than copper, and the ochre-yellow and brown decorations contain more copper than silver. This specific correlation only exists if the samples have the same type of glaze and, especially, a similar chemical composition. This means that the composition of the glaze has an important influence in the colouration process. Moreover, our investigations show that there is no relationship between the specular colour and the overall concentration of copper and silver. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 352–359, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10183
 
Article
The mysteries of the subjective relativity of colors are long recognized and of continuing fascination. It was the Greeks of antiquity who had not only noticed but also described the problem faced by weavers, who at times were confused by the color of the yarns when the source of light changed from the sun to an oil lamp. Similar problems were known to painters keen on reproducing nature faithfully. At the same time, there was the puzzling adaptation of our vision to the prevailing light, making a white fabric appear white in the light of the oil lamp as well as that of the sun. Simultaneous and successive contrasts, colored shadows, and other phenomena were all difficult to fit into a view of orderliness that Newton's findings appeared to propose. Leonardo da Vinci (1452–1519) has been named as the first painter who noticed colored shadows. As we will see below, Monge names the Abbé de Sauvages as having described them first. From the literature we know the descriptions of the Count of Buffon (1707–1788) and of Goethe (1749–1832).
 
Article
It is generally thought that Ewald Hering (19th century), or possibly Leonardo da Vinci (16th century), first recognized the concept of four unique hues (blue, green, yellow, red). However, in the Alhambra palaces, Granada, Spain, in a room roped off from tourist traffic, is a stained glass window featuring the four unique hues, built about 1370. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 364–365, 2006
 
Article
What is perhaps the first color specification system, developed in 1677 by the eminent English physician Francis Glisson, is described. Two of the scales for which Glisson provided quantitative data Glisson have been reconstructed: the gray scale in virtual form and the red scale in real form. Reflectance calculations or measurements and calculations of CIELAB L*a*b* values indicate that the two scales have a significant degree of uniformity despite the simple method used by Glisson to construct them. © 2002 John Wiley & Sons, Inc. Col Res Appl, 27, 15–19, 2002
 
Article
The development of the idea of simple or fundamental colors in Western culture from classical Greece to the early 17th century is shown, with particular emphasis on writers in the 16th and early 17th centuries. Four streams of thought are found: (1) Aristotle's seven colors, congruent with seven tastes and seven tones, thus symptomatic of an underlying general harmony; (2) Four-basic-color sequences where colors are emblematic of the four classical elements; (3) Spectral sequences; (4) Three simple chromatic colors between white and black, based on colorant mixture. In the late 16th century seven-color sequences came to represent categorical sequences, in addition to shorter fundamental color sequences. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 92 – 99, 2007
 
Article
The state of knowledge about color of the educated person at the end of the 17th century is discussed briefly and illustrated with a translation of pertinent material from a book on natural philosophy written by the Danish anatomist and physician Caspar Thomeson Bartholin and published in 1703.
 
Article
The painter Matthias Klotz began to investigate the subject of color beginning circa 1780 and thereby during the same general time period as Johann Wolfgang von Goethe, Philipp Otto Runge, and Gaspard Grégoire. Like the others, he was an adherent of the theory of three fundamental colors, yellow, red, and blue. With Grégoire he had in common three perceptual color attributes and an implicit cylindrical ordering system that presaged the system of Munsell, developed nearly a century later. With Runge and Grégoire he had in common a balanced color chart in which opposites were presumed to neutralize each other in a common medium gray. Klotz's so-called color canon is the most carefully executed in the early 19th century. He was unique in proposing a nine-grade, geometrically stepped gray scale that would require a logarithmic mathematical model. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 341–345, 2008
 
Article
Some 100 years before Albert Munsell developed his color order system, French silk merchant and inventor of a technology for producing works of art in silk velours, Gaspard Grégoire, introduced a color order system based on the color attributes hue, (relative) chroma, and lightness. Conceived in the mid-1780s, an atlas with 1350 samples was produced before 1813 and found use in French Royal manufacturing operations and educational institutions. It was followed a few years later by one with 343 samples. Grégoire's work was subsequently overshadowed by Michel-Eugene Chevreul's more complicated and less intuitive hemispherical system of 1839. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 5–9, 2008
 
Article
In the right half of the Munsell color space from 2.5R to 7.5BG, 90 colors were selected, most of which were at the lightness level V = 7, and in the left half from 2.5BG to 7.5R, 88 colors were selected most of which were at the level V = 4. Of these 178 colors, 176 pairs in the right half and 185 pairs in the left half were subjected to the following color-difference judgment. Subjects, five in number, selected two grays for which the lightness difference matches a given color difference in size. Two matrices (incomplete) of color differences given in terms of V were processed by MDSCAL, and finally one configuration of 178 points was synthesized in a three-dimensional Euclidean space. Implications of the results are discussed in connection with results of previous similar studies which were based upon much smaller numbers of colors.
 
Article
Georges Seurat first employed his divisionist painting technique, commonly called pointillism, on A Sunday on La Grande Jatte—1884 beginning in October 1885. Painting with pigments representing colors seen in the visible spectrum that were minimally mixed on the palette and using divided brushstrokes, he aimed to impart “luminosity” to the surface and to explore color theories that were being developed and disseminated at that time, such as simultaneous contrast, in his unique interpretation. In addition to the natural ageing of the painting materials causing an overall darkening of the painting, pigment analysis has disclosed that the brushwork containing zinc yellow has darkened significantly: yellow, green–yellow, and orange brushstrokes have become ochre-like, olive–green, and reddish–brown, respectively. By performing spectral reflectance measurements in situ on darkened areas of the painting and on paint-outs of comparable unaltered colors, using Kubelka–Munk turbid media theory, imaging the painting with color-managed digital photography, and image editing with Adobe Photoshop, a digital version of the original, more luminous appearance of La Grande Jatte was simulated. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 278–293, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20223
 
Article
Despite worldwide acceptance and usage of the Munsell color order system, accurate documentation of the experimental conditions associated with the original visual scaling experiments has not existed in the archival literature. Discussion with several coworkers involved in these scaling experiments has enabled us to provide a substantial portion of this documentation.
 
Article
The CIE system of colorimetry has been stretched to applications in industries and technologies that were not even envisioned when it was established in 1931. In general the standard observer has made this stretch gracefully. However, there has been a rash of recent articles in this and other journals suggesting that perhaps it is time to force the standard observer to retire. Often the apparent failings of colorimetry are due to its improper application or unrealistic expectations. This Color Forum reviews the status of the CIE standard observer and suggests that, while improvements are certainly possible, retirement would be premature.
 
Article
A physiologically plausible model of colour vision, based on the CIE 1931 standard colorimetric observer, is shown to provide a colour order system giving reasonably good predictions of the unique-hue loci, of constant-hue loci, and of constant-saturation loci, as judged by comparison with the Munsell and NCS systems, for daylight illumination. When combined with a chromatic-adaptation transform of the von Kries type, the model is also shown to give quite good predictions for real surface colours seen in tungstenlight (SA) illumination.
 
Article
The use of colorimetry within industry has grown extensively in the last few decades. Central to many of today's instruments is the work of the CIE system, established in 1931. Many have questioned the validity of the assumptions made by Wright(1) and Guild, some suggesting that the 1931 color matching functions are not the best representation of the human visual system's cone responses. A computational analysis was performed to evaluate the CIE 1931 color matching functions against other responsivity functions using metameric data. An optimization was then performed to derive a new set of color matching functions using spectral data of visually matched metameric pairs.
 
Article
A novel diffractive CIE 1931 chromaticity diagram is generated by utilizing surface relief gratings on a plastic sample. A properly illuminated sample is shown to reflect the CIE chromaticity diagram with exact colors and large gamut. Additive color mixing is accomplished by utilizing the four main peaks of a 4000 K fluorescent lamp's spectrum as the primary colors. The primary grating units are reflecting the combination of the primary colors to the desired viewing angle and thereby forming the correct chromaticity (x, y) at each pixel of chromaticity diagram. Weights of primary colors at each pixel of the diagram are controlled by fixing the relative areas of the primary gratings. The master grating is fabricated with aid of electron beam lithography. The final grating is hot embossed on a polycarbonate sample using an electroplated nickel shim. Chromaticity values are measured from the plastic sample by a spectroradiometer. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 409–413, 2007
 
Article
In this work, we determine the numerical data of the experimental color-matching functions (cmf's) of three real observers (JAM, MM, and CF) for two small fields (2°). In previous works, these cmf's have been shown generically and expressed only in a new system of unreal X′Y′Z′ primaries. Here, we show results found with these cmf's for the visible spectrum in intervals of 10 nm, from 400 to 700 nm. The data refer to both the RGB CIE-1931 system and a new system of unreal primaries X′Y′Z′, established by a procedure similar to that of the XYZ CIE-1931 system. This transformation was needed, because negative values appeared in various cmf's when they were referred to the XYZ CIE-1931 system. Recently, we have called this new system G94 (Granada ‘94). Here, we also describe the method and calculation of the matrix that enables this transformation; in testing six real observers with new cmf’s, we found positive results. We have used these new and experimental cmf's in several preceding works, as have other authors as well, to whom J. A. Martínez privately communicated the corresponding numerical data. The use of these cmf's by all the authors has led to noteworthy results. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 89–95, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10127
 
Article
Vos demonstrated that the Judd 1951 color-mixture diagram is a projective transformation of the CIE 1931 mixture diagram. He has provided transformation formulas for computing values of x′ and y′ from x and y, but he does not explain how the one set of data is derived from the other. Neither does Judd. Judd wanted the CIE to replace the 1931 V(Λ) curve with a new V(Λ) curve and to replace the 1931 XYZ diagram with a new X′Y′Z′ diagram. I have assumed that Judd started with the CIE 1931 RGB diagram. His X′Y′Z′ diagram can be derived from the RGB diagram if we use a different set of luminosity coefficients than those specified by the CIE. This change in luminosity coefficients was no doubt intended to compensate for the use of a new V(Λ) curve, but Judd has ignored the effect that this change in the luminosity coefficients should have on the alychne of the RGB diagram and the locus of spectral colors. This makes Judd's X′Y′Z′ diagram inappropriate for use in colorimetry and for use in building color-vision models. I have proposed a new solution to this problem.
 
Article
The presence of fluorescence in samples to be matched and in dyes to be used for matching requires precautions in measurement and in computation. Measurement of conventional reflectance may cause serious errors of formulation. Standard procedures for calculating matches are usually based on the additivity of the K/S values. In contrast, contributions of fluorescence have to be added to the spectral radiance factors. Specifications for a rigorous procedure are presented. Merits and shortcomings of currently used methods are discussed. An approximation making use of negative Kubelka-Munk coefficients is set forth. It is valid only for applications of a single fluorescent colorant which may be shaded slightly by minor additions of other colorants.
 
Article
The CIE 1976 colour spaces, CIELUV and CIELAB, have been compared by recalculating the results of a number of reported sets of experimental data. These include the results of just-noticeable-difference observations, colour difference scaling, colour matching ellipses, and acceptability ellipses. As a means of representing the colour difference data uniformly, it is shown that neither colour space is significantly better than the other. Attention is drawn to some anomalies in the CIELAB space.
 
Article
Sets of five colored-glass filters, identified as Standard Reference Materials 2101 through 2105 and intended for checking the performance of spectrophotometer-integrator systems, have been issued by NBS for many years. Highaccuracy transmittance measurements were performed on a set of the colored filters designated Master Set No. 3 by using a reference spectrophotometer constructed at NBS. A comparison of the new values with the original data obtained in 1962 for Master Set No. 3 shows agreement to within the experimental uncertainties of the 1962 measurements.
 
Article
The components comprising the CIE 1997 Colour Appearance Model, CIECAM97s, are described, and the steps needed to implement it in both forward and reverse modes are listed. A worked example is also given. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 138–146, 1998
 
Luo and Rigg experimental colour discrimination ellipses plotted in a* b* diagram.
Experimental ellipses close to the neutral axis plotted in a* b* diagram. The BFD, Leeds, RIT-DuPont, and Witt ellipses are plotted in black, red, green, and pink colours, respectively.
The E* ab /V values plotted against L* scale for the dataset accumulated by Chou et al. The lightness weighting functions of Eq. (4), the best fit polynomial, and CIE94 equations are also plotted using the solid, dotted, and doubledashed lines.
Article
A colour-difference equation based on CIELAB is developed. It includes not only lightness, chroma, and hue weighting functions, but also an interactive term between chroma and hue differences for improving the performance for blue colours and a scaling factor for CIELAB a* scale for improving the performance for gray colours. Four reliable colour discrimination datasets based upon object colours were accumulated and combined. The equation was tested together with the other advanced CIELAB based equations using the combined dataset and each individual dataset. It outperformed CMC and CIE94 by a large margin, and predicted better than BFD and LCD. The equation has been officially adopted as the new CIE colour-difference equation. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 340–350, 2001
 
Article
CMCCAT97 is a chromatic adaptation transform included in CIECAM97s, the CIE 1997 colour appearance model, for describing colour appearance under different viewing conditions and is recommended by the Colour Measurement Committee of the Society of Dyers and Colourists for predicting the degree of colour inconstancy of surface colours. Among the many transforms tested, this transform gave the most accurate predictions to a number of experimental data sets. However, the structure of CMCCAT97 is considered complicated and causes problems when applications require the use of its reverse mode. This article describes a simplified version of CMCCAT97— CMCCAT2000—which not only is significantly simpler and eliminates the problems of reversibility, but also gives a more accurate prediction to almost all experimental data sets than does the original transform. © 2002 John Wiley & Sons, Inc. Col Res Appl, 27, 49–58, 2002
 
Article
The CIE tristimulus values of measured Swiss Colour Atlas samples were converted to Munsell notations using a colour notation conversion program. A selected subset of SCA-2541 sample points was chosen: the samples on the fully populated regularly spaced hues 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60. The resulting Munsell notations were plotted onto Munsell Value-Chroma and Hue-Chroma planes and analysed for regularity of spacing and hue distribution around the achromatic axis. An earlier article has detailed the interrelation between the Natural Color System (NCS) and the Munsell Color Order System using similarly constructed charts. Comparison is made with the sample spacing of the NCS and SCA-2541 points when mapped into Munsell colour space, to determine similarities and differences between these two geometrically similar systems; both are double cones forming equilateral triangular constant hue planes. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 111–120, 1997
 
Article
An earlier article has compared the perceptual scaling of the Munsell, NCS, DIN, Coloroid, and OSA-UCS colour order systems. This article expands on the earlier article by presenting a comparison of the Colorcurve and SCA-2541 [Swiss Colour Atlas] colour order systems, again using the OSA- UCS system as a reference model. To enable direct comparison with the earlier article, the same varied but systematic sets of OSA- UCS cleavage planes were used in this new comparison. To enable comparison between these systems, and the Munsell, NCS, DIN, and Coloroid systems, thejndings are graphically presented in a format similar to that used in the earlier article. © 1994 John Wiley & Sons, Inc.
 
Article
The Farnsworth–Munsell 28-hue desaturated test (FM-28 desat) is a seldom-used derivative of the FM-100 panel arrangement test. In this study, we tested its sensitivity in patients suffering from diabetes mellitus. The patients were divided into 3 groups, according to whether they had no retinopathy, background retinopathy, or had undergone laser photocoagulation. Their results are compared to those of a control group with normal colour vision. The results show, in general, an increase in error score with duration of diabetes and with increasing severity of the disease. The errors are mostly not polarized towards any specific axis of the colour space. The FM-28 (desat) appears to be a sensitive indicator of the colour deficits associated with diabetes and is a viable alternative for clinical testing of colour vision. © 2000 John Wiley & Sons, Inc. Col Res Appl, 26, S292–S296, 2001
 
Article
The results obtained in colour vision tests can be influenced by many factors. It is possible that a learning effect disguises the fact that an acquired colour vision disturbance has progressively either deteriorated or been successfully treated. Therefore, the primary object of this study was to examine whether a possible learning effect occurred if screening by the colour vision test Roth 28-hue (E) desaturated was repeated several times, and if this learning effect was age dependent. Sixty-five ocularly and generally healthy subjects participated in the study and were divided into two age groups: group A: 20–39 years, n = 35; group B: 40–59 years, n = 30. Besides their ophthalmological status (visual acuity, refraction, intraocular pressure, cup/disk ratio, central fundus), the cap-sorting test Roth 28-hue (E) desaturated was performed under standardized test conditions. The measurements were repeated after 5 ± 1.72 days (T1), 15 ± 3.53 days (T2), 32 ± 6.97 days (T3), and 189 ± 16.85 days (T4). The ophthalmological parameters of all subjects were inconspicuous. The individual evaluation of the error scores in the cap-sorting test Roth 28-hue (E) desaturated showed large-scale variations. For both age groups there was no statistically significant difference between the right and left eye at any time. The mean values of the younger group remained relatively constant after the first measurement. This age group showed a quick, clearly visible learning effect that persisted over the whole test period. With regard to the older age group the average values deteriorated, remained solid for one month increasing again after 6 months. The results showed an age-related learning effect. Therefore, it is important to repeat the colour vision test within 5 days for the age group 20–39 years. This second test result will then serve as a stable basis for further comparative examinations within a period of 6 months. The subjects of the age group 40–59 years ought to repeat a first colour vision test after 5 and again after 15 days. The result of the second repetition will then offer stable basic values for subsequent tests. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 16–21, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20282
 
Article
Commercial ICC-compliant color-management software was used to produce color-managed CMYK-encoded images for the third edition of Principles of Color Technology. Custom profiles were created for a Scitex Eversmart Pro flatbed scanner and a Kodak Approval proofing device. This enabled objects such as color-order systems and colorimetric-encoded, computer-generated graphical images to be reproduced with reasonable colorimetric accuracy. The GretagMacbeth ColorChecker Color Rendition Chart was used as an independent verification target. Its printed reproduction had an average error of 4.2 ΔE (6.4 ΔE*ab). Colorimetric-rendering device profiles enabled the visualization of the book's color gamut and of a calibrated visible spectrum. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 360–373, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10083
 
Article
The accuracy of spectrophotometric measurements is limited by the standards that are used to calibrate the instrument. Therefore, the procedure used in transferring the spectral reflectance factor scale from one material to another for use in calibration must induce the minimum amount of error. the Munsell Color Science Laboratory has been transferring the spectral reflectance factor scale to calibration materials using a statistical method to correct for the most pervasive systematic errors in the measurement process. This method is based on a statistical procedure in which a set of systematic spectrophotometric errors are estimated based on the measurement of seven NIST primary standards and corrected in subsequent measurements. the optimization of the spectral reflectance factor scale to NIST standards minimizes the induced error. the average reflectance factor error consistently found between the corrected measurements of the NIST standards and their certificate values have been 0.0006 and the average δab has been on the order of 0.2.
 
Article
The NIST 0:45 reflectometer measures the spectral reflectance factor at an influx angle of 0° and an efflux angle of 45° of colored, nonfluorescent specimens at room temperature, with widths ranging from 3 to 10 cm and heights from 3 to 20 cm and with an uncertainty of less than 0.5 in color difference units. Published in 2008 by John Wiley & Sons, Inc. Col Res Appl, 33, 94–99, 2008
 
Article
We have determined optimal minimum-conspicuity monocoat paint colors for the CH-47F Chinook helicopter, viewed photopically against forest, desert, and sky backgrounds. Our methodology combines use of a validated spectroradiometric model for rigorous 3D signature prediction with statistics of varying background fields and a CIE color difference metric. The study considered a large subset of the Federal Standard 595 (FS595) paint inventory. Each paint color was rigorously modeled with bidirectional reflectance distribution function scattering properties to match existing army paint and spectral reflectances to match spectrophotometer measurements of FS595 reference samples. We devised and validated a method to impute statistical variation in background radiances over environmental conditions consistent with the aircraft radiometric computations. Using a visual jury, we informally calibrated the CIE 1994 color difference formula (which gauges both luminance and chromaticity contrast) to gauge how each paint performed against each background, for varying range, view direction, and sun location. The statistical dispersions in performance were summarized for the CH-47F Program Manager, who selected the best overall paint for the CH-47F fleet. We found paints that were optimized to a specific background (forest, desert, etc.) yielded enhanced performance against those backgrounds, as would be expected, and that those paints were better than the paint used on CH-47s in the current US inventory. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 406–416, 2009
 
Article
The original article to which this Erratum refers was published in Color Res Appl 2004;29:241–246No abstract.
 
Article
The effect of purity on hue has been reported severally (including Munsell and NCS data on constant hue loci) over 100 years but without general agreement. For example, the number of hue shift nulls in the data vary from 2 to 6. Hence, despite this effect's commonality it lacks reliable data for modeling underlying mechanisms or color appearance. The purity of a stimulus may be decreased by adding white (as in Abney's experiment), by adding black, or by adding gray such that luminance, or alternatively lightness, remains constant. This article gives new data for CRT stimuli for illuminant D65 for all four conditions but mainly for equal luminance, for 31 observers and 13 test dominant wavelengths. Further, samples were observed in two temporal conditions: either simultaneously as pairs (the contrast mode) or singly (the no-contrast mode). Three types of samples were tested: (1) equal luminance 30 cd/m2 for all dominant wavelengths, (2) equal lightness for all dominant wavelengths, and (3) zero-gray colors, requiring different luminances for different dominant wavelengths. In all the above conditions, the resultant hue shifts graphed a robust bimodal curve (two peaks in cyan and red, two troughs in blue and green) across the hue cycle, similar to Munsell and NCS data except the definite peak in cyan.© 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 25–39, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20286
 
Top-cited authors
Ming Ronnier Luo
  • Zhejiang University
Roy S. Berns
  • Rochester Institute of Technology
Guihua Cui
  • Wenzhou University
Li-Chen Ou
  • National Taiwan University of Science and Technology
Gaurav Sharma
  • Bangalore University