THE HOPELESS PURSUIT OF PURIFICATION IN CARTOGRAPHIC COMMUNICATION: A COMPARISON OF GRAPHIC-ARTS AND PERCEPTUAL DISTORTIONS OF GRAYTONE SYMBOLS

Simulation models are developed to determine the likely range of effects of edge growth caused by overinking during printing of dot-screen, parallel-line and crossed-line area symbols. Plausible amounts of edge growth, based upon experiences in printing Universal Product Code identifiers for food and household products, provide the basis for expanding the perimeters of the black image elements comprising an area symbol and thereby estimating the increased percentages of area inked. The effects of this type of reproduction noise, called fill-in, are simulated for amounts of edge growth representing both carefully monitored and low-quality printing. Graphs and measurements of Data Range/Inked Area curves are used to compare reproduction noise with published indicators of the perceptual distortion of values symbolized with graytones. These results indicate that printing is at least as significant a potential source of error in cartographic communication as perception. Attempts to improve map reading through ...