In
colorimetry
Colorimetry is "the science and technology used to quantify and describe physically the human color perception".
It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color ...
, whiteness is the degree to which a surface is white. An example of its use might be to quantitatively compare two pieces of paper which appear white viewed individually, but not when juxtaposed.
The
International Commission on Illumination
The International Commission on Illumination (usually abbreviated CIE for its French name, Commission internationale de l'éclairage) is the international authority on light, illumination, colour, and colour spaces. It was established in 1913 a ...
describes it in the following terms:
Calculation
where
*
is the Y
tristimulus value
The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defi ...
(
relative luminance
Relative luminance Y follows the photometric definition of luminance L including spectral weighting for human vision, but while luminance L is a measure of light in units such as cd/m^2, Relative luminance Y values are normalized as 0.0 to 1.0 ...
),
*
is the
chromaticity coordinate in the
CIE 1931 color space
The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defin ...
*
is the chromaticity coordinate of the
perfect diffuser (reference white)
The numbers in the subscript indicate the observer: two for the CIE 1931
standard observer and ten for the CIE 1964 standard observer.
Notes
* W increases with whiteness, reaching 100 for the perfect diffuser.
* The tint is green for positive T and red for negative T.
* Equal differences in W may not appear equally different.
See also
*
Color temperature
Color temperature is the color of light emitted by an idealized opaque, non-reflective body at a particular temperature measured in kelvins. The color temperature scale is used to categorize the color of light emitted by other light sources ...
References
* {{cite book, title=Colorimetry: Understanding the CIE System, first=János, last=Schanda, publisher=
Wiley Interscience
John Wiley & Sons, Inc., commonly known as Wiley (), is an American multinational publishing company founded in 1807 that focuses on academic publishing and instructional materials. The company produces books, journals, and encyclopedias, in p ...
, year=2007, chapter=Chapter 3: CIE Colorimetry, pages=68–70, isbn=978-0-470-04904-4
External links
ISO 105-J02:1997 Textiles -- Tests for colour fastness -- Part J02: Instrumental assessment of relative whitenessISO 11475:2004 Paper and board -- Determination of CIE whiteness, D65/10 degrees (outdoor daylight)ISO 11476:2000 Paper and board -- Determination of CIE-whiteness, C/2 degree (indoor illumination conditions)ISO/AWI 11476 Paper and board -- Determination of CIE-whiteness, C/2 degree (indoor illumination conditions)
* Konica Minolta Sensing
The colour of White
* TAPPI - why the CIE 1931 color space does not work for white paper
COMPARATIVE STUDY OF BRIGHTNESS/WHITENESS USING VARIOUS ANALYTICAL METHODS ON COATED PAPERS CONTAINING COLORANTS
Aksoy, Joyce, Fleming, Department of Paper and Printing Science and Engineering, Western Michigan University
Color
Papermaking
Shades of white