P3D Re: color temperatures

["Greg Wageman" <gjw@xxxxxxxxxx>]

-----Original Message-----
From: Rod Sage <rsage@xxxxxxxxxxxxxxxxxxxx>


>All this talk of color temps brings up a question. Don't our brains
>automatically adjust white balance so that we aren't so aware of the
>sickening green of fluorescent lighting or the orange cast of tungsten
>lamps etc.

Yes.  However, there are limits to what it can do.  Go look at various
familiar objects under a high-pressure sodium light, for example.  Some
colors will look black, because the sodium light simply doesn't emit at
some frequencies, and there's nothing your brain can do to compensate
for that.

>Why do camcorders etc.
>need automatic white balance. If they record the images in the same
>light we see them, wouldn't we be seeing them correctly? Do films
record
>light more accurately than we are able to perceive? Or are films
limited
>in their accuracy?


As I understand it, the problem is magnified with film because the
different emulsion layers have different sensitivities.  When you use a
daylight-balanced film under fluorescent light, which is lacking in
reds, the already less-sensitive red layer gets even less exposed.  The
resulting slide is highly deficient in reds.  You can't view what isn't
captured.

Also, I think for the brain to do the color correction, something close
to your entire field of view would need to be taken up by the image in
question, which is rarely, if ever, the case with a television or color
slide image.  An IMAX dome might do the trick. :-)  Although if the room
lighting were even more orange, say, than the unbalanced
tungsten-lighted image on the television from said camcorder, it might
look reasonably correct.

     -Greg W. (gjw@xxxxxxxxxx)





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End of PHOTO-3D Digest 3303
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