Depending on the type of coloring, color may apply to different sets of items:
See also: transparency, coulombic , mlp , measure convexity, surface, volume, Color Actions, Surface Color, Basic Actions, Selection Inspector, the Actions... Color menu, color schemes, color specification, palettes, limitations of transparency
Additional subcommands manage the set of named colors:
Usage: color spec colorname [ target string ] [ halfbond true | false ] [ transparency percent ]
Simple coloring applies to atomic models, including cartoon and molecular surface representations, volume data (map) displays, and 2D labels. The colorname can be:
The target option allows coloring only a subset of the possible displays of a given atom, residue, etc. The string can be any combination of the following letters, without commas or spaces:
Alternatively, for certain types of coloring, targets can be specified with one or more of the following keywords as a comma-separated list:
By default, bonds are shown in halfbond mode, with color and transparency settings from the flanking atoms. Setting halfbond false for a bond (or pseudobond) reveals its own color/transparency settings independent of the atoms. This option can be used to toggle halfbond mode regardless of whether the command colors any bonds. It affects only the specified bonds (not pseudobonds), except obeying the target setting when it includes p.
The transparency option sets transparency to the specified percent, where 0% is completely opaque and 100% is completely transparent. Existing transparency is not changed unless this option is used or the colorname explicitly specifies alpha (opacity). An alpha value overrides this option if both are given. Note that the transparency command can be used to set transparency apart from color. There are limitations in rendering transparency.
color /d & helix sky blue target cColor residues 12 and 260-275 in chains A and B, atoms/bonds only:
– or –
color /d & helix sky blue cartoons
color /A,B:12,260-275 hot pink target aColor all pseudobonds yellow:
– or –
color /A,B:12,260-275 hot pink atoms
color pbonds yellowRestore original model coloring to all carbon atoms:
color C bymodel targ aColor map #4:
color #4 medium violet
Usage: color sequential atom-spec [ level ] [ target string ] [ palette palette ] [ transparency percent ]
– or –
Usage: rainbow atom-spec [ level ] [ target string ] [ palette palette ] [ transparency percent ]
The color sequential command (synonym rainbow) applies a series of colors to atomic models at the specified level:
color seq resRainbow-color each biopolymer chain from blue at residue 1 to red at residue 50, leaving the colors of other parts unchanged.
– or –
– or –
rainbow :1-50Color the unique biopolymers in each atomic model, cartoons only, along the range cornflower blue → red → gold (chains that are the same biopolymer will be the same color):
color seq polymers targ c palette cornflowerblue:red:goldColor the 10-mer in PDB entry 1qmv using the 10-color version of the “paired” ColorBrewer palette:
– or –
rainbow polymers targ c palette cornflowerblue:red:gold
open 1qmv; rainbow chain palette paired-10
Usage: color modify spec hue [ + | − ] angle [ target string ]
Usage: color modify spec ( saturation | lightness | whiteness | blackness | red | green | blue ) [ + | − | * ] percent [ target string ]
Usage: color modify spec contrast [ percent ] [ target string ]
Color modification adjusts existing colors. It applies to atomic models, including cartoon and molecular surface representations. The color component to modify must be specified, with choices:
For saturation, lightness, whiteness, blackness, red, green, or blue, the percent can be added to (+), subtracted from (−), or multiplied by (*) the current value, or simply set as the current value if no operator symbol is given (or the space after the operator symbol is omitted; the space is needed to indicate a change from the current value rather than an absolute value). For hue, the angle can be added to or subtracted from the current value, or simply set as the current value.
Example image and script: Potassium Channel-Calmodulin Complex
Usage: color byattribute [a:][r:][m:]attribute-name atom-spec [ key true | false ] [ target string ] [ average residues ] palette-options [ transparency percent ] [ noValueColor color-spec ]
Atomic models can be colored to show the values of numerical attributes. Several attributes are present automatically, but others can be defined by the user arbitrarily or created by various ChimeraX tools and commands (details...). For example, the values of a map at atom positions can be assigned as an attribute with measure mapvalues. Examples of coloring by bfactor, an attribute automatically read from mmCIF/PDB, are given below. For coloring by a user-defined attribute, see the custom preset example. For coloring by segmentation region, see segmentation. See also the tutorial: Coloring by Sequence Conservation
An a:, r:, or m: immediately preceding the attribute name can be used to indicate the attribute level as atom, residue, or (atomic) model, but this is only needed when the name exists at multiple levels. The color-to-value mapping is specified with palette options (default
When color byattribute is run interactively (in gui mode and not via a script), the key true option can be used to start Color Key and draw a color key with the corresponding colors and values.
The coloring applies to atomic models, including cartoons and molecular surfaces, but can be restricted to certain representations with the target option. If an atom attribute is used, cartoons are colored by the average value of the atoms in each residue. Atoms (and their corresponding molecular surface patches) are colored by the atomic values unless average residue is given to indicate they should be colored by the average per residue.
The command color bfactor is shorthand for color byattribute bfactor. For example, to color chain A atoms by B-factor and cartoons by the average B-factor per residue, spreading blue-white-red coloring across value range 2-30:
color by bfactor /A range 2,30
– or –
color bfactor /A range 2,30
Regardless of whether the range of values over which to spread the coloring is specified, the full range of atomic values (or per-residue values if average residue is used) is reported in the Log.
If no range for colormapping is specified, the full range over all specified atoms is used for atom coloring and the full range of per-residue averages (over that same set of atoms) is used for cartoon coloring. Importantly, the value ranges will include solvent, ions, and ligands unless the specification excludes them, or they have been deleted beforehand. For example, to rainbow-color chain A atoms etc. by the average B-factor per residue, spreading the coloring across the full range of values from protein only:
color bfactor (/A & protein) palette rainbow ave residue
To apply attribute coloring to a surface cap (from clipping), it is necessary to first color the atoms by attribute, then use color zone to make the cap match the nearby atoms.
Usage: color ( sample | electrostatic | gradient ) surf-spec [ map map-model ] [ offset d ] [ key true | false ] [ update true | false ] [ palette palette ] [ range low,high | full ] [ transparency percent ]
The sample, electrostatic, and gradient coloring options color surfaces by volume data (map) values. To color atoms by map values, instead use measure mapvalues followed by color byattribute. Surface coloring by map value is also implemented in the Surface Color tool. The color-to-value mapping is specified with palette options, where the palette default is red-white-blue
color electrostatic #1 map #2 palette redblue range -10,10Same as previous except use royal blue instead of blue:
color elec #1 map #2 palette -10,red:0,white:10,royalblue
Usage: color radial surf-spec [ center point-spec ] [ coordinateSystem model-spec ] [ key true | false ] [ update true | false ] palette-options
Usage: color ( cylindrical | height ) surf-spec [ center point-spec ] [ axis vector-spec ] [ coordinateSystem model-spec ] [ key true | false ] [ update true | false ] palette-options
Coloring by distance applies to surfaces only, both molecular and nonmolecular (such as volume isosurfaces). It is also implemented in the Surface Color tool. The color-to-distance mapping is specified with palette options (default
Usage: color zone surf-spec near atom-spec [ distance cutoff ] [ sharpEdges true | false ] [ bondPointSpacing s ] [ farColor color-spec | keep ] [ update true | false ]
Coloring by zone to match nearby atoms or markers applies to surfaces only. The distance cutoff is specified in physical units, typically Å (default 2.0). The corresponding Map icon uses a distance value six times the grid spacing of the map. The graphical implementation, Color Zone, includes a slider for adjusting the cutoff distance.
For coloring a molecular surface (and/or its caps where sliced by clipping) to match the underlying atoms, a cutoff of at least the diameter of the surface-calculation probe (which defaults to 2.8 Å) is recommended. When multiple specified atoms fall within the cutoff distance of a surface vertex, the vertex will be colored to match the closest one. If bondPointSpacing is specified, points spaced s Å apart along bonds will be used in addition to the atoms to define the zone. The farColor option indicates how to color vertices that are not within the cutoff distance of any of the atoms: either a specific color or keep to retain their current colors. If the farColor option is not given, the single-color setting of the surface model will be used.
The sharpEdges option (default false) subdivides surface triangles to create sharp boundaries between the different colored regions. The update option (default true) indicates whether to update the coloring automatically when the shape of the surface changes.
A map that has been colored by zone can be split accordingly with volume splitbyzone. For coloring by segmentation region, see segmentation. See also: ChimeraX video: coloring each protein in an EM map
Usage: color single surf-model
The color single command removes surface per-vertex colors such as from coloring by value (attribute, map, distance, coulombic, or mlp), by zone, or by the atomic patches in a molecular surface. The surface model is returned to its single-color setting.
Usage: color image surf-spec [ file none | input-image-file [ modulate true | false ]] [ coords pole | south | sphere | vertexcolors ] [ writeColors output-image-file ]
Coloring by image applies to surfaces only. In this technique, also known as texture mapping, surface vertices are associated with U,V coordinates that map to the X,Y coordinates in an image. The file option specifies an image from a file to paste onto the surface (image format indicated by the filename suffix), or none, which clears any previous image coloring (since coloring by image does not work with undo). Omitting the file option keeps using the previously specified image, if any, for texture mapping. The modulate option indicates whether the image in the file should modulate rather than replace the current surface coloring (default false, which changes the underlying surface color to white so that the resulting coloring will come from the image only).
An image is rectangular, with XY coordinates (0,0) at the lower left corner and (1,1) at the top right. The coords setting indicates how UV coordinates should be assigned to surface vertices:
If the coords option is not used, UV coordinates are not assigned (for example, to allow using Python to assign them in some other way).
A palette is an ordered set of colors or value,color pairs used for sequential coloring or coloring by value (map, distance, or attribute). See also: coulombic, mlp, measure convexity
The palette can be specified as one of the following (or as ^palette to reverse the order of the colors):
- palette-name – the name of an existing palette; the command palette list lists the names of the available palettes in the Log. Predefined palettes include the following, with colors shown in ascending value order:
(default for sequential coloring)
- red-white-blue or redblue
(default for coloring by map value or coloring by distance)
- blue-white-red or bluered
(default for coloring by attribute)
- cyan-white-maroon or cyanmaroon
(default for measure convexity, along with range -1,1)
- grayscale or gray
(default for the mlp command, along with range -20,20)
(used to show the pLDDT confidence measure in the B-factor field of AlphaFold predictions)
0 50 70 90 100
- ColorBrewer palettes - a default number of colors will be used if the number is omitted from the name. Examples:palette pastel2-4Users should cite: www.ColorBrewer.org, color specifications and designs by Cynthia A. Brewer, Pennsylvania State University.
- color1:color2:color3... a series of color specifications separated by colons, collectively enclosed in quotation marks if it contains any spaces (example: palette cornflowerblue:red:gold or palette "cornflower blue:red:gold"). The colors are placed evenly along the range, with the first and last colors at the extremes. Colors for intermediate values are interpolated.
- value1,color1:value2,color2:value3,color3... a series of value,color pairs separated by colons, collectively enclosed in quotation marks if it contains any spaces (example: palette "0,cornflower blue:1,gold:0.7,red"). For sequential coloring, an entire range (such as the residues in each chain or the chains in each model) is always mapped to fractional values 0.0-1.0. For numerical data, the values can be expressed directly on the scale of the data (range not used) or as fractional values 0.0-1.0 across a range of data specified with range. Values below the lowest given value will map to the same color as the lowest, and values above the highest will map to the same color as the highest. Colors are interpolated between specified value-color pairs; discrete coloring can be achieved by specifying the same color for the upper- and lower-bound values of a “bin.” Reversing the colors in this type of palette specification with ^ is not recommended, as it would disrupt the specified color-value pairing.
- colourlovers-id – the ID number, name, or name+author of a palette to be fetched from COLOURlovers.com. Examples:palette 92095The page of a specific palette at COLOURlovers.com shows its name, author, ID number (in the URL), and any licensing stipulations for its use. Palette names with spaces must be enclosed in quotation marks. Palette names are not necessarily unique, and the most-viewed palette of a specified name will be fetched unless by author is appended, as in the example above. Palette and author names must be capitalized as shown on the website. Palettes with “all rights reserved” cannot be fetched. In ChimeraX, the palette colors are used in left-to-right order, spaced equally along the range of values. Web-fetched palettes are cached locally as described for open.
palette "Giant Goldfish"
palette "Giant Goldfish by manekineko"
palette "^Giant Goldfish"
range low,high | full
For numerical data only (not sequential coloring), what values should map to the extremes of the palette (default full, the minimum and maximum values for the items to be colored). Alternatively, low and high values separated by a comma only can be supplied. When multiple models are colored in a single command, the full range is determined separately for each model.
The command color name assigns cname as the name of the specified color. It can be used to define a new color name or redefine an existing one. A built-in color name, however, cannot be redefined. Color names must begin with an alphabetical letter and may contain only lowercase letters, numbers, hyphens, underscores, and spaces. If cname has embedded spaces, it must be enclosed in quotation marks. Examples:
color name tpurple 60,0,80,50
color name tgreen rgba(0%, 80%, 40%, 0.5)
Colors can be defined automatically at ChimeraX startup by including color name commands in the Startup preferences.
The command color delete can be used to “forget” a specific user-defined color or all custom (user-defined) colors. A built-in color name cannot be deleted. User-defined color names are saved in sessions.
The command color list lists color names along with color swatches in the Log, with options:
The command “color show cname” reports in the Log the rgba (red, green, blue, opacity) definition of an existing color named cname. See also: palette list