Color indices are set explicitly for each primitive brought in by the atoms, bonds, texts, polys, and ndots files. Each group of these may be set to a single color index through the appropriate control panel.
For each residue section in the ribbons, the `*.ss' file determines the ribbon's residue colors through a look-up table set in the `*.color' file. White is the default color if no look-up is set. Each chain may be set to a single color through the ribbons style panel. The different ribbon coloring schemes are also set with this panel.
WHATIF? If you use ribbons as part of the WHATIF modeling program, all the colors 1..39 form a spectrum based on the old PS300 color wheel, going from blue to red to green and back to blue.
The file `$RIBBONS_HOME/data/.matter' may be setup for alternative colors for all users. When the program begins execution it reads this file if present, then searches your current directory for `.matter', then `model_name.matter'. See the sample files there for examples.
An *.rgb file can be converted to black and white
and sharpened with the SGI utility `imgworks'
usage: imgworks image.rgb