= 100 and is roughly analogous to the munsell value scale times 10. For any measured color of lightness, L*, the coordinates (a*,b*) locate the color on a rectangular -coor-donate grid perpendicular to the L* axis at L*,The color at grid origin (a*= 0, b*= 0) is achromatic (gray). On the horizontal axis, positive a* indicates a hue of red-purple; negative a*, of bluish-green yellow and negative b* blue (Fig. 1).