Color in Cartographic Design 61
dimensions of color are utilized to create a
color solid. Value forms the axis of the
solid (Figure 4.5). Grays are arranged from white at the top to black at the bottom
in a series of equal steps, which are numbered from 1 to 9. At the middle position
on the gray scale (5) is middle or neutral gray; a plane passed through this point is a
color circle with hues of middle lightness. Around the outer part of the solid, called
the “equator” by Munsell, there is a decimal scale of hues merging gradually into one
another, beginning and ending at red. The plane is also visualized as passing from
the surface inward to the axis. The colors become less strong as one approaches the
axis and stronger as the equator is neared. These represent the saturation, chroma, or
strength of the color. Because not all colors have the same number of steps of satura-
tion, the solid formed is not a sphere, but is asymmetrical. At each position on the
gray scale, a series of rings shows different values. Each hue becomes lighter as one
goes from the white pole of the solid and darker as one goes to the black pole. These
rings are themselves color wheels. The hues arranged on the color wheel are specified
by initial. Thus, any color can be specified by a letter and two numbers, and any new
color can be assigned a place on the solid.
spot colors
While the systems above are useful for describing and understanding color, printed
colors are chosen and described for the printer by a system analogous to the paint
chips provided to a painter. Printers have a color specification chart that specifies the
amounts of the three subtractive primaries and black necessary to create a specific
color. The most common of these charts is the Pantone Matching System. Plate 4.4
shows the range of colors that can be produced from just two hues and shows the
percentages of each hue used.
When creating colors at the computer and viewing them on screen, most illus-
tration software programs have a function that gives quantities according to several
different color models. CorelDraw allows CMYK (cyan, magenta, yellow, black),
White
Black
1
2
3
4
5
6
7
8
9
R
Y - R
Y
R - P
P
G-Y
P-B
B
B - G
GREEN
1
2
3
4
5
SATURA
TION
