POV-Ray : Newsgroups : povray.binaries.images : Stock colors and gamma : Stock colors and gamma Server Time
3 Jul 2024 00:56:23 EDT (-0400)
  Stock colors and gamma  
From: Cousin Ricky
Date: 29 Nov 2014 18:40:01
Message: <web.547a5854fa17f5da192ae5f10@news.povray.org>
As a rule, I don't use named colors in computer applications, because I am
convinced that the bureaucrats who assign colors to names are colorblind.
However, it seemed to me early on that something else was going on with the
named colors in colors.inc.  Most of them seemed too pale, and many were
entirely the wrong hue.

About 2 years ago, I wrote a scene to plot the stock colors in a 3-D HSL
structure, just to get an idea of how they were distributed.  After seeing all
the colors at once, labeled, it occurred to me:  What if the colors were
assigned using gamma 2.2 or sRGB?  After all, I had gotten the sense that
assumed_gamma was a fairly new feature at the time I discovered POV-Ray, and it
would seem reasonable that the colors were not assigned with linear rendering in
mind.

I have used assumed_gamma 1 in nearly all of my scenes since the day after I
downloaded POV-Ray.  Literally.  (I checked.)  It's just something I don't even
think about.  I re-rendered the scene with gamma 2.2, and the color assignments
made a lot more sense.

The other day, I wrote a scene to display the two versions of the stock colors
side-by-side.  (Most of the grays are omitted.)  The scene uses assumed_gamma 1.
 The left half of each test object uses the color straight from colors.inc.  On
the right half, the sRGB transfer function is applied.

Having solved this mystery, colors.inc is still not off the hook.  Coral, to me,
is not a synonym for orange.  The Pink looks more like puce.  SlateBlue and
MediumSlateBlue look far brighter than any slate I've witnessed, and I don't
know what "steel blue" even means.  (Steel looks a neutral to warm gray to me.)
Worst of all, the color named "Flesh" is /totally/ unrealistic.  DarkWood is
much closer to the flesh color over most of my body, with my palms and soles
between MediumWood and Feldspar depending on the computer monitor, the position
of my hand, and the temperature of the room.

P.S. The timing with A.D.B.'s post is pure coincidence.


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