This link offers a quick and easy arithmetic and graphical tool to convert to and from various colour scales, standard illuminants and standard observers. For example you can convert from L,C,H to CIELAB to Hunter L,a,b. It will recalculate the values of any scale based on changing, for example, the Standard Illuminant from D65 to Cool White Fluorescent or Incandescent, or the Standard Observer from 2 degrees to 10 degrees and back.

Set three scroll bars to L*, a*, and b* values; see plot and color swatch change, display of values in three CIE metrics and RGB.