COLOR AND PATTERN I. THE NATURE OF COLOR II. COLOR DIMENSIONS III. COMPUTER ELECTRONIC DISPLAY COLOR MODELS IV. COLOR COMBINATIONS V. COLOR GUIDELINES

Nature of Color What is Color? A product of the mind. Spectral color vs. reflected color

Color Dimensions Albert Munsell codified color so that it has 3 separate dimensions: –hue (color name) –lightness (value) –saturation (chroma)

Color Dimensions 1. Hue -- various colors of the spectrum. Use less than 12 hues.

Color Dimensions 2. Lightness (value) Difficult to deal with in practice. –intensity not easy to differentiate –intensities look different on different backgrounds Most often used with ordinal data b/c value clearly has some order associated with it.

Color Dimensions 3. Saturation--(chroma, intensity, or purity). For any given hue, saturation varies from 0% (neutral gray) to 100% (maximum color).

Computer Electronic Display Color Models In GIS & computer cartography there are three main electronic display color modeling systems: RGB Color Model HLS Color Model CMYK Color Model

Additive (black to color)

Subtractive (white to color)

Color Combinations 1. The most pleasant color combinations result from large differences in lightness. 2. Good background color is either light or dark. a. To be pleasant, an object color must stand out from its background color by being definitely lighter or darker (cartography). 3. Pleasant object colors are hues in green to blue range. Hues w/ little or no gray most pleasant. 4. Unpleasant object colors are in yellowish-green range. 6. Vivid colors combined with grayish colors tend to be judged as pleasant.

Color Guidelines Cynthia A. Brewer, “Color Use Guidlines for Mapping and Visualization”. In: Visualization in Modern Cartography, eds. A.M. MacEachren and D.R. Fraser Taylor, Elsevier Science Inc., NY, p Organization based on hue and value, lesser extent saturation

Color Guidelines One Variable Color Schemes 4 basic color scheme types: –qualitative –binary –sequential –diverging

Make sure each hue is subordinate to the one above

Color Guidelines Two Variable Color Schemes seldom just use one variable, usually use two or some cases more. allows detailed comparisons of distributions.

Shows where variables are simultaneously either highly or lowly valued

Dark hues at four corners and vary lightness in between.