[filmscanners] RE: Gamma and Color

["michael shaffer" <michael@shaffer.net>]

Dana writes ...

> ...
> An interesting exercise is to create a color step wedge and apply
> different gamma values to it. You will see that whatever
> primary color has the smallest value gets the greatest boost
> if gamma is larger than unity. This occurs in the popular color
> spaces of Adobe RGB (1998) and sRGB. Note that if the primaries
> are equal (that is, the pixel is gray), they all get the same boost
> and the result is still gray. But if one color is dominant (foliage
> or skintones, for instance), the hue will change. This is a real
> problem if I am trying to preserve *both* skin tones and grayscale!
> ...

  I might suspect this, but only for severe tonal adjustments ... i.e., no
color space is perfect.

  As to why and how to avoid it, you may want to submit the same query to
the gurus who reside within the Adobe forums.  Goto adobeforums.com, and
register for the "color management" forum (a link on the right).  You'll
need to subscribe, and then bookmark the forum.  Lots of good info, and I'll
be watching for responses to your query.

cheerios ... shAf  :o)
Avalon Peninsula, Newfoundland
www.micro-investigations.com


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