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At least 163 records · Page 9Linked to original sources
PubMed1993

Pharmacological studies on cutaneous inflammation induced by ultraviolet irradiation (1): quantification of erythema by reflectance colorimetry and correlation with cutaneous blood flow.

This study was conducted to quantify the intensity of ultraviolet (UV) erythema in guinea pigs, a method for evaluating anti-inflammatory drugs, and to clarify any correlation of erythema with cutaneous blood flow. Skin color and cutaneous blood flow in non-administered and indomethacin-administered animals were measured by a colorimeter and a laser Doppler flowmeter over time after UV-irradiation treatment. Skin color was indicated by a XYZ colorimetric system and L*a*b* color space. In either colorimetric system, the values of two indices, x and y or a* and b*, increased along with the intensification of erythema. The increase in the chroma (C*) value calculated from a* and b* was UV-dose-dependent. This value was significantly suppressed by indomethacin 0.5-4 hr after irradiation, and it was found to be a clear and sensitive index for evaluating the suppressive effect of drugs. Cutaneous blood flow also increased with UV irradiation. Indomethacin significantly suppressed this increase 2-3 hr after UV irradiation. The changes of cutaneous blood flow correlated with those of C*. These results suggested C* was a suitable parameter to quantify UV erythema, and the change of skin color in UV erythema reflected the change of cutaneous blood flow.

Animals↗
PubMed1976

A method for the treatment of metamerism in colorimetry.

All of the spectrally different colors that match according to an observer form a metamer ensemble. We present a new method to generate the metamer ensembles for both direct light and reflecting-surface-color problems. The method is based on the properties of particular metameric functions (the simple elements) and is particularly appropriate for treating problems of theoretical limits of metamerism. The method is illustrated with several practical examples and is compared with previously known methods.

Color Perception↗
PubMed1996

Frederic Ives Medal paper. History and current status of a physiologically based system of photometry and colorimetry.

The CIE chromaticity diagram, which has been in common use for more than 60 years, disguises essential relations among cone excitations that become transparent in a system developed with D. I. A. MacLeod and initially proposed by the author to the CIE in 1979. This proposal led to the formation of a CIE committee to consider an ideal version of the system, to be employed either as a supplement to, or an alternative for, the 1931 "standard observer". After 15 years, the task remains unfinished. The history of debate within the original committee and that of its successor (which is still active today) is briefly reviewed. Among cone fundamentals that might be chosen, a set derived and published by Stockman, MacLeod, and Johnson [J. Opt. Soc. Am. A 10, 2491 (1993)] is favored here, and some of the advantages for displaying visual data in a system based on these fundamentals are illustrated.

Color Perception↗
PubMed2003

Colorimetry for CRT displays.

We analyze the sources of error in specifying color in CRT displays. These include errors inherent in the use of the color matching functions of the CIE 1931 standard observer when only colorimetric, not radiometric, calibrations are available. We provide transformation coefficients that prove to correct the deficiencies of this observer very well. We consider four different candidate sets of cone sensitivities. Some of these differ substantially; variation among candidate cone sensitivities exceeds the variation among phosphors. Finally, the effects of the recognized forms of observer variation on the visual responses (cone excitations or cone contrasts) generated by CRT stimuli are investigated and quantitatively specified. Cone pigment polymorphism gives rise to variation of a few per cent in relative excitation by the different phosphors--a variation larger than the errors ensuing from the adoption of the CIE standard observer, though smaller than the differences between some candidate cone sensitivities. Macular pigmentation has a larger influence, affecting mainly responses to the blue phosphor. The estimated combined effect of all sources of observer variation is comparable in magnitude with the largest differences between competing cone sensitivity estimates but is not enough to disrupt very seriously the relation between the L and M cone weights and the isoluminance settings of individual observers. It is also comparable with typical instrumental colorimetric errors, but we discuss these only briefly.

Colorimetry↗
PubMed2006

A nonradioactive assay for poly(a)-specific ribonuclease activity by methylene blue colorimetry.

A simple nonradioactive assay, which was based on the specific shift of the absorbance maximum of methylene blue induced by its intercalation into poly(A) molecules, was developed for poly(A)-specific ribonuclease (PARN). A good linear relationship was found between the absorbance at 662 nm and the poly(A) concentration. The assay conditions, including the concentration of methylene blue, the incubation temperature and time, and the poly(A) concentration were evaluated and optimized.

Colorimetry↗
PubMed1984

Colorimetry for the stain technologist. I. The specification of color.

This paper describes color specification for the stain technologist. The principles of color stimulus specification are reviewed in terms of the conventions of the Commission Internationale de l'Eclairage (CIE). The text is largely self-contained and has been written so that it can be understood easily by a reader with no prior knowledge of color science. The paper starts with definitions of color and related psychological, psychophysical and colorimetric terms. X, Y, Z color space is described. It is shown that any color stimulus may be unambiguously defined in terms of a set of three numbers. The CIE 1931 Chromaticity Diagram is described. Worked examples are given for the calculation of tristimulus values and chromaticity coordinates using three different illuminants. The usefulness of color specification is illustrated by a number of examples using Romanowsky stained blood cells or Papanicolaou stained epithelial cells from the uterine cervix.

Blood Cells↗
PubMed1984

Colorimetry for the stain technologist. II. The specification of chromaticity difference.

This paper describes the calculation of chromaticity difference. The text has been written specifically for the stain technologist and is largely self-contained. The concept of a uniform chromaticity scale (UCS) is described. A UCS is a diagram in which equal perceived differences in chromaticity are represented by equal distances anywhere on the diagram. UCSs are developed by transformations of the CIE 1931 chromaticity diagram, and may be linear (projective) or nonlinear. The effectiveness of the various transformations has been assessed using published data on discrimination of chromaticity. The usefulness of chromaticity difference calculations is illustrated by histological examples, including Romanowsky stained blood cells and Papanicolaou stained cells from the uterine cervix. Six UCSs are used in these examples, two projective and four nonlinear.

Animals↗
PubMed1984

Colorimetry for the stain technologist. III. The specification of color difference.

This paper illustrates the calculation of color differences, involving luminance as well as chromaticity components. Color differences have been calculated for a large number of stained histological objects. Four different color difference formulae have been used, namely, those associated with the FMC 2, U*V*W*, L*u*v* and L*a*b* systems. Comparison has first been made between various hematological substrates after staining with two different azure B-eosin Y stains. Next, comparison is made for the same substrates after staining with one of the azure B stains and a methylene blue-eosin Y stain. Pairwise comparison is also made of various substrates from the epithelium of the uterine cervix after Papanicolaou staining. Finally, pairwise comparison documents color differences accompanying maturation for the erythroid and myeloid cell lines in azure B-eosin Y stained bone marrow. The limitations of current color difference formulae are discussed.

Blood Platelets↗
PubMed1985

Colorimetry for the stain technologist. IV. Analysis of the components of color difference.

Total color differences have been calculated for various pairs of stained microscopic substrates. The latter include azure B/eosin stained blood cells and Papanicolaou stained cells from the uterine cervix. Both the CIE L*u*v* and L*a*b* color spaces have been used. Total color differences have been analyzed in terms of lightness, hue and chroma components. Various discrepancies have been noted among these components, especially the chroma difference, for the two spaces. It is concluded that current color-difference formulae are less than perfect, although they can provide much useful information.

Azure Stains↗
PubMed1996

[A study on colorimetry of oral mucosal lesions].

Color observation is essential to diagnose oral mucosal lesions. In order to measure and record the color of the oral mucosa more objectively, colorimeters were evaluated. The noncontact-type colorimeter showed considered values comparable with those of visual color matching and was reliable. The color distribution of the normal oral mucosa was from 5.0R to 4.1YR in hue, 3.5 to 6.0 in value, and 3.7 to 6.7 in chroma. The color distribution of leukoplakia was from 2.6RP to 3.4YR in hue, 3.7 to 7.0 in value, and 0.3 to 8.3 in chroma and the ranges thereof were considerably broader than those of normal mucosa and other mucosal lesions. The higher chroma of leukoplakia was, the severer epithelial dysplasia was. The color distribution of oral cancer was from 3.0R to 8.2YR in hue, 2.7 to 6.4 in value, and 3.0 to 7.8 in chroma. The ranges of color distribution was broader than those of normal mucosa and narrower than those of leukoplakia. The color distribution of lichen planus was from 1.7R to 8.9R in hue, 3.5 to 6.3 in value, and 3.6 to 8.5 in chroma. The chroma of erythema is the highest of all mucosal lesions. Some oral mucosal lesions are suggested to have characteristic colors.

Adult↗