RasMol/Chime Color RGB Values
Excerpted from the RasMol Reference Manual

by Eric Martz -- Apr 13, 1998; revised Dec 5, 1998, Jan 9, 2000


Computer screen colors are made up from light intensities of three primary colors, Red, Green, and Blue (RGB). Hence, any color can be specified as an RGB triplet of intensity values. Usually, each intensity can range from 0 to 255 decimal, which is 00 to FF hexadecimal.

RasMol's color command uses decimal RGB triplets, whereas HTML requires hexadecimal triplets. This is why both forms are given below. To make the word Nitrogen appear in RasMol's CPK color for nitrogen [143,143,255], the HTML syntax is <font color="#8F8FFF">Nitrogen</font>.

Chime 2.0 can accept color commands in hexadecimal as well as RasMol-style decimal. In Chime 2.0, the selected atoms can be colored, for example, dark green with the command "color [x00A000]", which simplifies the construction of html text with a matching color.

For converting decimal values to hexadecimal and vice versa, in Windows 95: Start, Programs, Accessories, Calculator. Enter a decimal number and select Hex.

If you frequently wish to use a color not predefined, you can write a one-line script. For example, if you make the file gray.spt containing the line

color [180,180,180] #grey

then the command script "gray.spt" colors the currently selected atom set gray. (In commands, RasMol accepts both British and American spellings, e.g. colour or color). The advantage is that if you later wish to change the color, you need change only the RGB values in the script file, and then everywhere this script is used, the color will become the new shade automatically.

The RGB values below have been verified with the source code for RasMol version 2.6 beta 2a (file transfor.c).

RasMol's Predefined Color Names

    NAME         RASMOL           HTML
    black        [0,0,0]          00 00 00
    white        [255,255,255]    FF FF FF

    blue         [0,0,255]        00 00 FF
    green        [0,255,0]        00 FF 00
    red          [255,0,0]        FF 00 00

    yellow       [255,255,0]      FF FF 00
    magenta      [255,0,255]      FF 00 FF
    cyan         [0,255,255]      00 FF FF

    orange       [255,165,0]      FF A5 00
    redorange    [255,69,0]       FF 45 00
    violet       [238,130,238]    EE 82 EE
    purple       [160,32,240]     A0 20 F0
    greenblue    [46,139,87]      2E 8B 57

Be careful: these names do not give the same colors in HTML.

CPK Colors

    Carbon                    light grey       [200,200,200]  C8 C8 C8
    Oxygen                    red              [240,0,0]      F0 00 00
    Hydrogen                  white            [255,255,255]  FF FF FF

    Nitrogen                  light blue       [143,143,255]  8F 8F FF
    Sulphur                   sulphur yellow   [255,200,50]   FF C8 32
    Chlorine, Boron           green            [0,255,0]      00 FF 00

    Phosphorus, Iron, Barium  orange           [255,165,0]    FF A5 00
    Sodium                    blue             [0,0,255]      00 00 FF
    Magnesium                 forest green     [34,139,34]    22 8B 22
    Zn, Cu, Ni, Br            brown            [165,42,42]    A5 2A 2A

    Ca, Mn, Al, Ti, Cr, Ag    dark grey        [128,128,144]  80 80 90
    F, Si, Au                 goldenrod        [218,165,32]   DA A5 20
    Iodine                    purple           [160,32.240]   A0 20 F0

    Lithium                   firebrick        [178,34,34]    B2 22 22
    Helium                    pink             [255,192,203]  FF C0 CB
    Unknown                   deep pink        [255,20,147]   FF 14 93
See the Manual for a color-graphic summary of the CPK colors.

Structure Colors

The RasMol structure color scheme colors the molecule by protein secondary structure.

Structure                   Decimal RGB    Hex RGB

Alpha helices  red-magenta  [255,0,128]    FF 00 80  *
Beta strands   yellow       [255,200,0]    FF C8 00  *

Turns          pale blue    [96,128,255]   60 80 FF
Other          white        [255,255,255]  FF FF FF

*Values given in the 1994 RasMol 2.5 Quick Reference Card ([240,0,128] and
[255,255,0]) are not correct for RasMol 2.6-beta-2a. This correction
was made above on Dec 5, 1998.
The secondary structure is either read from the PDB file (HELIX and SHEET records), if available, or determined using Kabsch and Sander's DSSP algorithm. The RasMol structure command may be used to force DSSP's structure assignment to be used.

Custom Color Scheme

If you wish to use a custom coloring scheme, it is typically much simpler to construct a short script to accomplish this than to insert values into the PDB file. The script also has the advantage that it can be invoked for any currently displayed molecule. An example of such a script is contained in the Chime Template as file cs_amphi.spt (Color Scheme AMPHIpathic).

define temporary selected
select protein
color [208,208,208] #gray
select protein and backbone
color [100,50,100] #dull magenta
select protein and not (hydrophobic or backbone)
color magenta
select temporary
The first and last lines make sure that whatever was selected before the script was run remains selected after it is finished. If you want the color scheme to apply ONLY to what is selected before the script is run, use this form:
define temporary selected
select protein and selected
color [208,208,208] #gray
select protein and backbone and selected
color [100,50,100] #dull magenta
select protein and not (hydrophobic or backbone) and selected
color magenta
select temporary