Choropleth Map Production by Facsimile

Abstract

A continuous tone image can be produced by facsimile to simulate the various shaded patterns of a choropleth map. The image can be subsequently screened for half-tone reproduction. Up to 255 hues of tone can be reproduced. The facsimile technique removes the need for finding manufactured tones whose visual intensity is closely proportional to the data value, thereby forcing the cartographer to debate the significance of class generalisation.