[magick-users] Suggestion to Digital Photo Handling section, part 2

[- Tong -]

Hi Anthony,

On http://www.imagemagick.org/Usage/photos/, you have a minor
underexposure example.

Before going into -sigmoidal-contrast operator, maybe it is a good
idea to first discuss convert's built-in -normalize operator that
is similar to GIMP's "auto-levels" or "normalize" feature that
stretch pixel values from darkest to brightest. 

 convert minor.jpg -normalize minor.normalized.jpg

Also, maybe you'd like to through in how IM can also create the
three-color histogram out of it:

 convert minor.jpg histogram:- | convert - minor.histogram.jpg

Looking at the histogram, I think it may explain what you wrote:

__________________________
Sigmoidal contrast brightening tends to de-emphasize the red end
of the spectrum. You may end up having to select a parameter that
results in the most natural flesh tones, rather than the
brightness level you really want.
__________________________


-- 
Tong (remove underscore(s) to reply)
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