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  • The equal contrast gray scale
  • Research to date on equal value gray scales has produced results that are in disagreement. This may be attributed both to the experimental techniques used and the bounded nature of the gray spectrum. This study employs a task directly analogous
  • to that faced by map readers trying to distinguish gray tones on a classed choropleth map: the measurement of perceived contrast between gray tone pairs. Equal contrast scales of five to ten tones are iteratively calculated using trend surface équation. Power
  • functions are calculated for each of these six equal constrast gray scales and for the combination of all of them.
  • The effects of background on the equal value gray scale
  • A real gray tone symbols produced on standard line printers seldom adhere to acceptable cartographic design standards. The recent development of matrix line printers provides an alternative means of producing more effective map symbolization
  • with a device also suitable for ordinary character output. Matrix printers permit a greater range of gray tones in a regular sequence, more uniform symbol configuration, and improved print quality.
  • , the maps has the appearance of a continuous change in gray tone corresponding to the surface it represents.