Whiteness Index (WI) displays XXX.X
When taking a measurement for Whiteness Index (WI) the instrument must be set to one of the following illuminant/observer combinations (per ASTM E313-98):
C/2°, C/10°, D50/2°, D50/10°, D65/2°, D65/10°
Setting the instrument to any other illuminant/observer will cause the output to be XXX.X
