README
1This directory contains several alternative rgb databases:
2
3 old-rgb.txt the version that was shipped in previous
4 releases; this was originally "tuned" for
5 the Digital VT240 series terminals.
6
7 raveling.txt lots of new colors, tuned by Paul Raveling
8 at ISI for the HP monitor; see below.
9
10 thomas.txt a version of the older database that was
11 tuned by John Thomas at Tektronix to match
12 a box of Crayola crayons; see below.
13
14
15Notes from Paul Raveling:
16
17 1. Many colors have been tuned for an HP monitor -- mine,
18 to be exact. Some of the old values were obnoxious enough
19 to bring complaints from users (like "That's Wheat???!!!");
20 so far early user reports on the new RGB database are favorable.
21
22 2. File rgb.txt was reorganized into 3 sections:
23
24 a) Light and off-white colors, copied from several Sinclair
25 Paints color samples. The intent for adding these is
26 to provide a better choice for light-colored window
27 backgrounds.
28
29 BTW, I wanted to find ANSI standard colors, but ANSI
30 happily gobbled my $16 without sending the specification
31 I ordered, Then they ignored my followup letter.
32 Nuts to ANSI & "ANSI standards".
33
34 b) Special colors such as black, white, and favorite
35 shades of gray.
36
37 c) A spectrum of colors, arranged to transition gradually
38 between nearby colors, running from generally blue
39 colors through green and ending with generally red colors.
40 This includes all colors from the old X11R3 database,
41 but they're no longer in (mostly) alphabetic order.
42
43 d) The gray scale from the original X11R3 database.
44
45
46 Within the "spectrum of colors" section there are clusters
47 of colors, each consisting of:
48
49 1. One or more Specially named colors. If more than one
50 is present, all are related by lying on a common line
51 running from RGB = (0 0 0) [pure black] to a single
52 point on the surface of the RGB color cube.
53
54 2. Four colors at particular points on the same line in
55 RGB space. Their names end in "1", "2", "3", and "4",
56 with "color1" being at the surface of the color cube
57 and the others at increasing distances approaching black.
58 Distance of these color points from black is approximately
59 logarithmic. This attempts a rough fit to human
60 perception's sensitivity to intensity.
61
62 Here's an example of one of these clusters:
63
64 210 105 30 chocolate
65 139 69 19 saddle brown
66 139 69 19 SaddleBrown
67 255 127 36 Chocolate1
68 238 118 33 Chocolate2
69 205 102 29 Chocolate3
70 139 69 19 Chocolate4
71
72 Note that the "original" colors, in this case chocolate
73 and saddle brown, don't always match the scaled points.
74
75
76 Does anyone think these changes are a good idea? Crummy idea?
77 Do you have other favorite colors? Can anyone do better at
78 matching some tough colors? Some colors, especially reddish
79 ones, were VERY hard to reproduce, & I'd welcome contributions
80 from other HP users who can get a better match.
81
82
83
84Notes from John Thomas:
85
86Advised by our human factors folks that "standard" named colors exist, but
87only for well-controlled color coordinate systems (like CIE, but not for RGB),
88I sat down one evening with the handiest standard of subjective color names,
89a box of 72 Crayola crayons. (Believe it or not, over 50% of the colors from
90rgb.txt were represented.)
91
92Using an X-client implementation of the TekColor model, I created the following
93list of named colors. Appearance on your monitor may vary because of brand,
94age, and video drive circuitry, but I think you will find it a better match
95for the average monitor, than the original rgb.txt file from MIT.
96
97
98 John C Thomas
99 Tektronix, Inc.
100 Wilsonville, OR
101 jct@windex.TEK.COM
102