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[filmscanners] RE: Eyedroppers in Curves in Nikon Scan

Jerry writes ...

> Addendum to the Gray point eyedropper behavior in Photoshop.
> Using it re-maps pixel values to neutral, but not necessarily to
> middle gray.
> For instance, in Photoshop 6.01, in curves, I have the gray point target
> values specified as 128,128,128.
> ...
> Clicking on a gray card in an image with pixel values of 106,118,106, the
> values are re-mapped to 110,109,110.  Pretty close to being neutral, but
> not the specified 128,128,128.

  Referring to Bruce Fraser's article:
Out of Gamut: Color-Correcting Photographs in Photoshop

 ... here is what he has to say:

      "The gray eyedropper [...] moves the color of pixel on
      which you click towards the target value while retaining
      its native brightness and some of its color, again
      adjusting the rest of the image by the same amount."

Martin Evenin writes:

      "The Gray Balance Eyedropper does not assign brightness
      values; it is used purely to neutralize colors that
      have any tonal brightness."

  ... which only leaves to question ... "if it adjusts gray balance only,
how do you set the target values?  ... that is, how is a target of
128/128/128 different from 77/77/77???"  But, I do suppose it allows you to
set a target gray value which is NOT neutral (... for whatever reason ...)

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

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