The correct notation is L*a*b*.
The L*a*b* space is a fixed standard, so any defined value will ALWAYS be accurate.
The three components are:
• L* - lightness - ranges from 0 (no lightness) to 100 (maximum lightness).
• a* - red-to-green value (+128 red, -128 green).
• b* - yellow-to-blue value (+128 yellow, -128 blue).
This uniform color space proposed by the CIE is used in the measurement of small color differences. The lightness (L*) and the color parameters (a* b*) accurately define a color.
Because the L*a*b* space is a fixed standard, any defined value (color) will be the same in any L*a*b* color space. Therefore, if you define an L*a*b* value of 65,5,-110, any L*a*b* compatible program or device can correctly interpret it as the exact shade of blue that you originally designed it as. However, the source (input) and target (output) of that color is almost always either RGB or CMYK. This is where profiles can help - they properly translate the desired color from either RGB or CMYK to L*a*b* and vice versa.
See Color Management.
See Device - Independent Color Space.
See Color Model.
See also CIE (Commission Internationale de l'Éclairage).
