CIE 15 Colorimetry

The "CIE 15 Colorimetry" standard, developed by the International Commission on Illumination (CIE), aims to provide a consistent and comprehensive account of the CIE's basic colorimetry recommendations. This standard summarizes basic colorimetric data and practices, but does not deal with color appearance specification.

This standard includes recommendations grouped into seven categories:

• Recommendations on standard physical data of illuminants and sources
• Recommendations regarding the reflection standard
• Suggestions regarding geometric conditions
• Recommendations regarding standard observer data
• Recommendations for calculating tristimulus values ​​and chromaticity coordinates
• Recommendations regarding uniform color range and color differences
• Recommendations on various colorimetric applications and formulas

Recommendations regarding standard physical data of illuminants and sources are as follows:

• Recommendations regarding standard physical data of illuminators
• Artificial sources representing illuminators

Recommendations regarding the reflectance standard: The perfectly reflective diffuser is the reference standard for reflectance. It is defined as the ideal isotropic diffuser with a reflectance equal to unity. For actual measurements, reflectance standards such as pressed barium sulphate or PTFE should be calibrated with respect to the perfectly reflective diffuser for the required geometry.

Recommendations regarding geometrical conditions: The terms and definitions used in this section introduce terminology that was not used in previous editions of this standard. Namely,

• Proposed nomenclature for directional irradiation
• Recommended geometry for reflection measurements
• Recommended geometry for transmission measurements

Recommendations regarding standard observer data:

• CIE 1931 standard colorimetric observer
• CIE 1964 standard colorimetric observer

Recommendations for calculating tristimulus values ​​and chromaticity coordinates:

• Calculation of tristimulus values
  • Secondary light sources (reflecting or transmitting objects)
  • Illuminators and self-luminous objects
• Use of abbreviated or truncated data
  • Abbreviation
  • Abbreviation
  • Weighting factors
  • Numerical procedures
  • Bandwidth of a spectrometer
• Calculation of chromaticity coordinates
• Equations representing relationships between color stimuli

Recommendations regarding uniform color range and color differences:

• CIE 1976 uniform chromaticity scale diagram (UCS diagram)
• CIE 1976 uniform color spaces
  • CIE 1976 (L*a*b*) color space, CIELAB color space
  • CIE 1976 (L*u*v*) color space, CIELUV color space
  • Notes on CIE 1976 uniform color spaces
• Improved industrial color difference assessment
  • CIEDE2000 total color difference formula

Recommendations for various colorimetric applications and formulas:

• Dominant wavelength and purity
  • Dominant wavelength (of a color stimulus)
  • Complementary wavelength (of a color stimulus)
  • Colorimetric purity
  • Purity of stimulation
• Specific metamerism indices
  • Specific metamerism index: change in illuminant
    • Tristimulus values ​​under reference illuminant
    • Tristimulus values ​​under test illuminator
    • Colour difference and metamerism index
  • Specific metamerism index: change in the observer
    • Tristimulus values ​​for standard colorimetric observers
    • Tristimulus values ​​for standard deviation observer
    • Colour difference and metamerism index
• Assessing the quality of a daylight simulator for colorimetry
• Evaluation of whiteness
• Calculation of correlated color temperature: The concept of correlated color temperature was previously based on visual observations. Recent studies have shown that no metrological definition can be made based on such perceptual studies. Therefore, a new definition has been proposed. The definition is compatible with the previously proposed calculation method and therefore does not cause any changes in the calculated values.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the "CIE 15 Colorimetry" standard.