Given current computer technology, color is seldom NOT an option Color is fundamentally important to cartography and fundamentally confusing In the past: traditional printed maps: expensive and difficult to use color Given current computer technology, color is seldom NOT an option color is often misused with new technologies Exciting and Dangerous Allows greater design options color is confusing and there are no specific standards Color is seen differently by different people Viewing conditions Emotional reaction Additive and Subtractive Color Models and Specifications many different ways to specify colors

Electromagnetic Spectrum Figure 14.1 Electromagnetic Spectrum

But much more sensitive Color Perception Retina Rod Cells No color detection But much more sensitive Cone Cells Sensitive to Blue, Green and Red

Figure 14.3

Applies to maps on computers Figure 14.4 Color Theories Additive Applies to maps on computers Subtractive Applies to printed maps Since almost all maps are made on computers now…

Table 14.1

Components of Color Hue (color) Saturation (sometimes chroma) Figure 14.5 Components of Color Hue (color) Saturation (sometimes chroma) Intensity or purity Value Lightness or darkness

Figure 14.6

Figure 14.7 Color Models HSV

Figure 14.8 Additive (RGB)

Figure 14.8 Subtractive CMY(K)

Lesser used color models HSB/HSL Basically the same as HSV CIE

Device Limitations Gamut Web Safe Colors Dynamic range of possible colors Web Safe Colors 0,51,102,153,204, 255 20 % increments Supposedly displayed exactly the same on almost all machines. Makes a total of 216 different colors Color Matching Systems Pantone Like picking out a paint color at Lowes.

Figure 14.9 Color interaction

Simultaneous Contrast

Successive Contrast

Visual Acuity

Advance and Retreat

Hysometric effect

Colors in Combination Best combinations result from differences in lightness Good background should be light or dark Consistently pleasing objet colors – blue to green, others containing little grey Unpleasent – yellow or yellowish – those containing large amount of grey Must stand out and be vivid (string combined with grey ok)

Table 14.3

Table 14.4

Table 14.5

Color Conventions Blue for Water Red to Blue – Warm to Cool scale Green to Yellow to Tan or Brown – Vegetation to bare areas Different categories should be different hues

Table 14.6

General Harmony Rules Most people like pure hues and shades Red better than purple Black better than gray Colors on opposite or next to each other on the color wheel harmonize best.

Color advise for maps: http://colorbrewer2.org/ Color Hue and Color Value and Choropleth Maps

One Variable Color Schemes Qualitative Schemes Binary Schemes

One Variable Color Schemes Sequential Schemes

One Variable Color Schemes Diverging Schemes

Two and Three Variable Color Schemes

Two and Three Variable Color Schemes