Guideline
The CIE-Lab-System is a color space, which was specified by the International Commission on Illumination CIE (Commission Internationale d'Eclairage) in 1976. It was further derived from the CIE color system and is based on the CIE "master" space which was introduced in 1931. The CIELab system today is the most common color system. On the basis of this equipment independent 3D-colour model, color differences can be identified numerically. The model is impartial and complies nearly with the human perceptiveness, by adapting the geometrical distance between two colors in the color space with the human perception.

Especially graphic works with scanner, printer and monitor requires an accuracy for colors in an international significant color profile space, which assure a correct appropriateness of colors. The consistent color space furthermore provides for a larger variety of hues, more than i.e. RGB and CMYK. The measured distance is not corresponding to the sensed color difference by test personal, therefore the CIE model was revised several times and out of this CIELab was deflected. Independent of the used equipment, the color code of the CMYK- and RGB-mode can be exchanged in CIELab color values and can also be used in graphical software.
This model is suitable especially for surface colors, while CIE-Luv is in use for the evaluation of light sources at monitors and scanners. How is CIELab configured? The measured spectral curves will be reduced on three coordinates. The axes of the coordinates are positioned rectangular on each other:
L* ,the light intensity, from 0 = absolute black to 100 = absolute white.
a* describes the red - green axis. Negative values are green, the positives are red.
b* describes the yellow - blue axis. Negative values are blue, the positives are yellow.

Therewith the color can be accurately described in the color space. The calculation is effected under consideration of a standard light and an ordinary observer, that is, the color values are calculated under defined physical conditions. On the layer a* / b* , it achieves the chromatic circle. At the edges are the polychromatic colors and in the center a chromatic grey is located.

Functionality
Continuous, controlled LED illumination and identification of the product color in the color space after CIELab. The evaluation results in the visible light sector from 400 - 700 nm. The distance between sensor system and product has to be kept obligatory absolute non-varying.

The color evaluation, that is the output of the measurement results, occurs in 4 channels: L*, a*, b* and dE*.

Configuration

Housing:                   aluminum pressure cast housing  
　　　Size HxWxD       230 x 280 x 110 mm
　　　Enclosure          IP65 / NEMA 4
　　　Color                RAL 5024

Connections:                                        
　　　Power supply           100-240V AC
　　　4 analog outputs      0/4 - 20 mA
　　　2 PC interfaces        RS 232 or RS 485
　　　Sensor connection    fiber optic cable
　　　sensor system          LED-illumination

User interface          
　　　Operating               6 soft keys in integrated keypad
　　　Monitoring              2 x 24 characters in illuminated display

Ambient conditions
　　　Environment temperature     -20°C - +85°C
　　　Product temperature           >0°C - +130°C