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Tyner indb
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Bog'liq Judith A. Tyner. Principles of map design. New York. „The Guilford Press”, 2010dImensIons of coloR
The term hue was used frequently in the previous discussion instead of color. Color
actually has three dimensions, of which hue is only one. Hue refers to the sensation
we perceive when light of a specific wavelength strikes the eye. Thus, red, green, blue,
and violet are hues. But we recognize that there are many variations of red or blue.
We commonly speak of “light blue” or “deep blue,” “greenish blue” or “purplish
blue.” Some shades of blue seem somehow “bluer” than others. These descriptions
represent attempts to describe the other two dimensions of color: lightness and satu-
ration. Lightness is also called value, but when working with quantitative data that
may have high or low numerical value the term can be confusing.
If we create a sequence of grays ranging from white to black with a series of pro-
gressively darker grays in between, we have produced a gray scale (Figure 4.4). The
closer a gray is to white, the lighter it is or the higher its value; the closer to black,
the darker it is and the lower its value. We can compare colors to the gray scale and
establish lightness steps for different hues; a blue that is near the white end of the gray
scale has a high value, and a blue that is near the black end has a low value (Plate 4.2).
As we shall see in the next section, some color systems quantify the lightness of hues
so that they can be compared and described.
Saturation, also called purity, intensity, or chroma, refers to the “colorfulness”
of a hue. It is the extent to which the color deviates from a gray of the same value. A
pure spectral color has a high intensity; it is fully saturated (Plate 4.3).
VIOLET
BLUE
GREEN
YELLOW
ORANGE
RED
SHORT
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