Commission on Illumination

The International Commission on Illumination (abbreviated CIE from the Erench expression) over the years has recommended a series of methods and standards ia the field of color for a history of this process see Reference 8. 

Color Difference Evaluation. Shade evaluation is comparable in importance to relative strength evaluation for dyes. This is of interest to both dye manufacturer and dye user for purposes of quaUty control. Objective evaluation of color differences is desirable because of the well-known variabihty of observers. A considerable number of color difference formulas that intend to transform the visually nonuniform International Commission on Illumination (CIE) tristimulus color space into a visually uniform space have been proposed over the years. Although many of them have proven to be of considerable practical value (Hunter Lab formula, Friele-MacAdam-Chickering (FMC) formula, Adams-Nickerson formula, etc), none has been found to be satisfactorily accurate for small color difference evaluation. Correlation coefficients for the correlation between average visually determined color difference values and those based on measurement and calculation with a formula are typically of a magnitude of approximately 0.7 or below. In the interest of uniformity of international usage, the CIE has proposed two color difference formulas (CIELAB and CIELUV) one of which (CIELAB) is particularly suitable for appHcation on textiles (see Color). 

Objective Evaluation of Color. In recent years a method has been devised and internationally adopted (International Commission on Illumination, I.C.I.) that makes possible objective specification of color in terms of equivalent stimuli. It provides a common language for description of the color of an object illuminated by a standard illuminant and viewed by a standard observer (H). Reflectance spectro-photometric curves, such as those described above, provide the necessary data. The results are expressed in one of two systems the tristimulus system in which the equivalent stimulus is a mixture of three standard primaries, or the heterogeneous-homogeneous system in which the equivalent stimulus is a mixture of light from a standard heterogeneous illuminant and a pure spectrum color (dominant wave-length-purity system). These systems provide a means of expressing the objective time-constant spectrophotometric results in numerical form, more suitable for tabulation and correlation studies. In the application to food work, the necessary experimental data have been obtained with spectrophotometers or certain photoelectric colorimeters. 

Under the guidance of the hitemational Commission on Illumination (Commission Internationale de TEclairage or CIE), several color description systems and notions have been developed and have established the present procedures ... 

CIE (Commission Internationale De L Eclairage)—international commission on illuminants responsible for establishing standard illuminants. 

The International Commission on Illumination (CIE) International Commission on Illumination (CIE) has defined a set of standard illuminants to be used for colorimetry (International Commission on Illumination 1996). Figure 3.21 shows the CIE illuminants A, C, Z>5o, Z>55, Z>65, and D15. Illuminant A represents the power spectrum of light from a black-body radiator at approximately 2856 K. If this type of light is required for experiments, a gas-filled tungsten filament lamp that operates at a temperature of 2856 K is to be used. Illuminant Z>65 represents a phase of daylight with a correlated color temperature of approximately 6500 K. The CIE recommends to use this illuminant wherever possible. 

Figure 3.21 CIE illuminants A, C, D50, H55, D s, and D75 (data from International Commission on Illumination 1996).

The International Commission on Illumination (CIE) has defined a standard observer to be used for accurate color reproduction (International Commission on Illumination 1983, 1990, 1996). In Chapter 2 we have seen that the rods mediate vision when very little light is available. This type of vision is called scotopic vision. The cones mediate high acuity vision in bright light conditions. This type of vision is called photopic vision. The sensitivities for a standard observer as defined by the CIE for scotopic and photopic vision are shown in Figure 4.3. The scotopic function is denoted by V (k). The photopic... 

Figure 4.3 Sensitivities as defined by CIE, which are used to model scotopic V (X) and photopic vision VM(k) of a standard observer (International Commission on Illumination 1983, 1990, 1996) (data from International Commission on Illumination 1988).

Using these sensitivities, we can calculate the luminous flux of any light source (International Commission on Illumination 1983 Jahne 2002). Let (/,) be the radiant flux at wavelength X of the light source. Let V (X) be the sensitivity of scotopic vision and V(X) be the sensitivity of photopic vision, then the intensity of the light source is... 

In 1976, the CIE defined a three-dimensional color space that is perceptually more uniform than the CIE XYZ color space (International Commission on Illumination 1996). The... 

Another perceptually approximately uniform color space is the CIE L a b color space (Colourware Ltd 2001 International Commission on Illumination 1996). This color space was intended for use with surface colors. The three coordinates L, a, and b are computed from the tristimulus values X, Y, and Z as follows ... 

A summary of symbols and units that are used in radiometry is shown in Table B.l. A summary of symbols and units that are used in photometry is shown in Table B.2. The photometric quantities use the same symbol except that the subscript v is added. A good introduction to the theory of radiometry is given by Poynton (2003), Jahne (2002), Horn (1986), and Levi (1993). See also International Commission on Illumination (1983). The radiometric units refer to physical quantities whereas the photometric units refer to perceptual quantities. In photometry, the physical quantities are weighted by the spectral sensitivity of the human visual system. Let Q(X) be the energy at wavelength X. Then, the corresponding photometric quantity is given by... 

International Commission on Illumination 1983 The Basis of Physical Photometry, second edition. Technical Report 18.2, International Commission on Illumination. 

International Commission on Illumination 1988 CIE Photometric and Colorimetric Data. Technical Report D001, International Commission on Illumination. 

International Commission on Illumination 1990 CIE 1988 2° Spectral luminous Efficiency Function for Photopic Vision. Technical Report 86, International Commission on Illumination. 

American Society for Testing and Materials International Commission on Illumination charge transfer particle diameter diffuse reflectance... 

Light and lighting, radiation International Commission on Illumination (CIE) http //www.cie.co.at/ciecb... 

Items 4 and 5 are correct and have been taken in to account by the Commission Internationale de L Eclairage [CIE, International Commission on Illumination] in their development of the standard, the basis for other national and international standards. 

Commission Internationale de L Eclairage (CIE). International Commission on Illumination. Recommendation for the integrated irradiance and spectral distribution of simulated solar radiation for testing purposes. CIE, No. 20 (TC 2.2). Paris, France Bureau Central de la CIE, 1972. 

In contrast to the patchwork-like Munsell system, the CIE system and its modifications (developed by the International Commission on Illumination, CIE, in 1931) create numerically continuous color spaces. They are based on the principle of tricliromaticity of vision which states that the... 

It is well known that the spectral distribution and irradiance of the solar radiation at the Earth s surface depend on the location and is subjected to seasonal and diurnal variations. Therefore, a reference spectrum is needed as a basis for comparison with the spectral energy distribution of artificial light sources. Data from CIE No. 15 1971 (colorimetry official recommendations of the International Commission on Illumination) that recommend a standard illuminant D65 with a scheduled color temperature of approximately 6500 K have been used as a basis over the years. 

CIE (1986) Colorimetry, Official recormnendations of the International Commission on Illumination. CIE Publication No. 15.2, Vieima CIE Central Bureau. 

The function V(X), as adopted by the International Commission on Illumination (CIE), is tabulated and plotted below. 

The spectrum of red wines has a maximum at 520 nm, due to anthocyanins and their flavylium combinations, and a minimum in the region of 420 nm. Color intensity and hue, as defined by Sudrand (1958), only take into account the con-tribntions of red and yellow to overall color. Of conrse, the resnlts of this partial analysis cannot claim to reflect the overall visual perception of a wine s color. Application of the CIELAB universal color appreciation system, proposed by the International Commission on Illumination, certainly represents an improvement, but the results are difficult for winemakers to interpret. 

The most important of the systems not based on collections of physical color samples is what is known as the CIE system. This system was developed by the Commission /nternational de I Eclairage (International Commission on Illumination). 

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