raveling@isi.edu (Paul Raveling) (10/20/89)
In the copy of X11R3 in use on ISI's HP workstations I've updated the RGB data base in several ways that may be of interest to others, particularly HP users. I'll post a copy of /usr/lib/X11/rgb.txt in a following article for the benefit of anyone who'd like to check it out. Also, see my announcement from earlier tonight about updated Img software for a program to display the color database. Changes in this rgb.txt are: 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. ---------------- Paul Raveling Raveling@isi.edu