Reflectance value relative to the perfectly reflecting and perfectly diffusing surface, which is assigned a value of 1.0.
Process by which light or other electromagnetic radiation is converted into heat or other radiation when incident on or passing through material.
Conformity of a measured result to an accepted reference value or scale.
A neutral color, such as white, gray or black, that has no hue. Also termed nonchromatic.
The angle between the axis of an impinging light beam and the perpendicular to the specimen surface.
The angle between the axis of observation and the perpendicular to the specimen surface.
Distinguishing characteristic of a sensation, perception or mode of appearance. Distinction is made between chromatic and geometric appearance attributes.
The attribute of visual sensation by which an observer is made aware of differences in luminance.
The graphical or mathematical relationship of a desired property to an instrument's output.
Perceived as having a hue - not white, gray or black.
Those attributes associated with the spectral distribution of light, hue and saturation.
That part of a color specification which does not involve luminance.
A uniform-color space utilizing an Adams-Nickerson cube root formula, suggested in 1976 for adoption by the CIE in 1976 for use in measurement of small color differences.
The ratios of each of the tristimulus values of a color to the sum of the tristimulus values. In the CIE system they are designated by x, y and z.
A plot of the relative magnitude of the visual response as a function of wavelength from about 380 nm to 770 nm, adopted by CIE in 1924.
A hypothetical observer having the tristimulus color-mixture data recommended in 1931 by the CIE for a 2° field of vision (x, y, z or x2, y2, z2). A supplementary observer for a larger 10° field (x10, y10, z10) was adopted in 1964.
The amounts of the three reference or matching stimuli required to give a match, with the color stimulus considered, in a given trichromatic system.
In English, the International Commission on Illumination; the main international organization concerned with color and color measurement.
The characteristic of a transparent material whereby distinct images may be observed through it.
Color difference based on the CIELAB color scale which can automatically generate tolerances for perceptible or acceptable differences.
A three-dimensional characteristic of the appearance of an object, light source or aperture. One dimension usually defines the lightness and the other two together define the chromaticity.
Substantial invariance of object-color perceptions in the presence of changes in illumination or viewing conditions.
The magnitude and character of the difference between two object colors under specified conditions.
A system of specifying numerically the perceived attributes of color.
The visual sensation produced by light of different wavelengths throughout the visible region of the spectrum. By such perception an observer may distinguish differences between two objects of the same size, shape, and structure.
View a demonstration on how to measure the color difference between a pair of samples and see what the values mean.
UltraScan VIS is a visible-range, high-performance color measurement spectrophotometer that measures the full range of human color perception. It can be used in production and in the laboratory.
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The USP and EP Color Standards are visual color standards, intended to improve color communication between sites by defining a sample color as being close to physical liquid standard ("near USP F"; "near EP Y2") rather than using words ("light yellow"). Read Vol. 20, No. 8 (PDF)
