HSL (and the related HSV) are different color spaces designed to represent "perceptual color relationships" better than RGB (red-green-blue). The idea is that you are breaking down a color into a hue, a saturation, and a lightness (or value). This representation is supposed to be more robust to variations in lighting.
However, converting to and from HSL/HSV is a fairly complicated operation. LabView and WindRiver should have code to do this for you already - just be warned that you don't want to be spending all your time converting between color spaces!
For more info:
http://en.wikipedia.org/wiki/HSL_and_HSV