Color Spectrum File Format

Color spectrum files [.CLR] are used to define a spectrum, or continuous gradation of colors. This is specified by a series of anchor points with associated colors. The colors between anchor points are interpolated from the nearest anchor points.

The basic format consists of an ASCII file with header information on the first line. Subsequent lines specify anchors points, one anchor point per line.

The header consists of the following space-delimited fields:

Element Description
Id case-sensitive string "ColorMap" without the quotes
Version format version number, this should be set to 1
InterpMethod interpolation method between anchors, this should be set to 1


Subsequent lines define the anchor points, one per line. Each line has the following space-delimited fields:

Element Description
Position The position is the floating point percentage value (from 0.0 to 100.0). Positions must be specified in increasing order from 0 to 100 percent, and the 0 and 100 percent positions must be specified in the file
Red red color component (0 to 255)
Green green color component (0 to 255)
Blue blue color component (0 to 255)


In the following example, the anchor points are at 0, 50, and 100. The zero position is blue, the 50 percent anchor is green, and the 100 percent position is yellow.

ColorMap 1 1

0 0 0 255
50 0 255 0
100 255 255 0


It is also possible to have coincident anchor points in a color file. Anchors and colors are interpreted in order from 0 percent to 100 percent. In the case of coincident points, you can create distinct boundaries, similar to the example shown here.

ColorMap 1 1

0 255 0 0
50 255 255 0
50 0 0 255
100 255 255 255

See Also

Color Gradient

3D Settings

3D XYZ Bubble Plot