Bryan,
Thanks very much. In my case, to set a WB in my living room, could I say that the correct position where I should place the WhiBal card is to put it under the same lighting as my main subject?
Hi Eric,
That's correct. What you are trying to determine is the average color of the illumination and ambient light. Then software can try to render objects to reflect the color they would have under that given illumination.
Also, I kind feel WB value may not be some fixed value like room temperature for example, but rather is an approximation and is allowed to vary by preference (say I want a little warmer or cooler). Does this sound right?
Yes, what one wants is a reference that allows to render objects with the correct reflected color. From there on one can add a warmer or cooler atmosphere, at the photographer's discretion. Compare it with shooting under an evening sky with a setting sun. One will use white balancing to remove disturbing color casts from ambient reflected colors, and then dial in a better color temperature to set the appropriate atmosphere.
Nearby strongly colored reflections, e.g. colored walls/furniture/grass/etc., can dominate the local ambient color temperature. That too can be important for the local ambiance, so reintroducing
some of it may be warranted, as long as the most important (memory) colors are not getting too much of a cast. Skincolor e.g. will look ugly under a blue or green ambient lighting, but can tolerate a red or orange ambient lighting much better.
Cheers,
Bart
