Datacolor Spyder3 Elite Help Manual page 63

Select White Luminance Reduction
Help Index
Usual Setting
This setting will be 'off' except for special circumstances. Turn this setting 'on' if you
experience a color cast when calibrating a display that does not have a White
Luminance control or whose White Luminance control is already at its minimum setting.
The Purpose of This Step
This setting provides an option that may allow users of some displays
to achieve a more acceptable calibration.
The Long Answer
Some displays may be set to produce very high White Luminance output. This setting
may be so high that it causes clipping of the RGB channels which can result in a color
cast.
Normal calibration depends on the user being able to adjust the White Luminance of
the display using controls on the display itself. Some displays have no such control or
their control may not have sufficient range to reach an appropriate setting.
White Luminance can also be adjusted in software by the calibration. Normally this is
not done because it can result in reduced dynamic range. Turning this setting 'on'
allows the calibration process to adjust White Luminance in software for the benefit of
color cast reduction with the possible trade-off of reduced dynamic range.
Further Information
For information such as a list of Frequently Asked Questions and details on all
Datacolor products be sure to visit our website: www.datacolor.com/Spyder3