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This directory contains several alternative rgb databases:
old-rgb.txt the version that was shipped in previous
releases; this was originally "tuned" for
the Digital VT240 series terminals.
raveling.txt lots of new colors, tuned by Paul Raveling
at ISI for the HP monitor; see below.
thomas.txt a version of the older database that was
tuned by John Thomas at Tektronix to match
a box of Crayola crayons; see below.
Notes from Paul Raveling:
1. Many colors have been tuned for an HP monitor -- mine,
to be exact. Some of the old values were obnoxious enough
to bring complaints from users (like "That's Wheat???!!!");
so far early user reports on the new RGB database are favorable.
2. File rgb.txt was reorganized into 3 sections:
a) Light and off-white colors, copied from several Sinclair
Paints color samples. The intent for adding these is
to provide a better choice for light-colored window
backgrounds.
BTW, I wanted to find ANSI standard colors, but ANSI
happily gobbled my $16 without sending the specification
I ordered, Then they ignored my followup letter.
Nuts to ANSI & "ANSI standards".
b) Special colors such as black, white, and favorite
shades of gray.
c) A spectrum of colors, arranged to transition gradually
between nearby colors, running from generally blue
colors through green and ending with generally red colors.
This includes all colors from the old X11R3 database,
but they're no longer in (mostly) alphabetic order.
d) The gray scale from the original X11R3 database.
Within the "spectrum of colors" section there are clusters
of colors, each consisting of:
1. One or more Specially named colors. If more than one
is present, all are related by lying on a common line
running from RGB = (0 0 0) [pure black] to a single
point on the surface of the RGB color cube.
2. Four colors at particular points on the same line in
RGB space. Their names end in "1", "2", "3", and "4",
with "color1" being at the surface of the color cube
and the others at increasing distances approaching black.
Distance of these color points from black is approximately
logarithmic. This attempts a rough fit to human
perception's sensitivity to intensity.
Here's an example of one of these clusters:
210 105 30 chocolate
139 69 19 saddle brown
139 69 19 SaddleBrown
255 127 36 Chocolate1
238 118 33 Chocolate2
205 102 29 Chocolate3
139 69 19 Chocolate4
Note that the "original" colors, in this case chocolate
and saddle brown, don't always match the scaled points.
Does anyone think these changes are a good idea? Crummy idea?
Do you have other favorite colors? Can anyone do better at
matching some tough colors? Some colors, especially reddish
ones, were VERY hard to reproduce, & I'd welcome contributions
from other HP users who can get a better match.
Notes from John Thomas:
Advised by our human factors folks that "standard" named colors exist, but
only for well-controlled color coordinate systems (like CIE, but not for RGB),
I sat down one evening with the handiest standard of subjective color names,
a box of 72 Crayola crayons. (Believe it or not, over 50% of the colors from
rgb.txt were represented.)
Using an X-client implementation of the TekColor model, I created the following
list of named colors. Appearance on your monitor may vary because of brand,
age, and video drive circuitry, but I think you will find it a better match
for the average monitor, than the original rgb.txt file from MIT.
John C Thomas
Tektronix, Inc.
Wilsonville, OR
jct@windex.TEK.COM
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