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Proceedings Paper

Method of separating scanned maps into arbitrary colorants using filter images and logical operators
Author(s): Patrick D. Fryer; Tony Johnson
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Paper Abstract

This paper describes a process for separating a map, originally printed using an unknown ink specification into its component colors before being reprinted using a known ink specification. The methodology is based on two earlier papers by Kanamori and Kotera, (1991) and Harrington (1992) in which the use of logical operators in color central were explored. A detailed analysis of the scanned map identified primary, secondary and transition colors. Filter images containing pixels taken from across the scanned image were developed to describe the variation of color found within each of these color groups. The maximum and minimum values of hue, lightness and chroma were then used to derive logical operators and true/false statements which when applied to L*a*b* pixel arrays separate the scanned map it into its primary color components. This technique was refined to include secondary and transition colors. By combining true/false statements it was possible to separate more specific areas within the scanned map. The method was used to reproduce the map using the known ink specification with a (Delta) E value ranging between 2.1 (Yellow) to 11.9 (Black), for the known and unknown ink specifications. It was also used to change geographic features represented by each color component through the addition and deletion of color detail.

Paper Details

Date Published: 21 December 1999
PDF: 10 pages
Proc. SPIE 3963, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts V, (21 December 1999); doi: 10.1117/12.373401
Show Author Affiliations
Patrick D. Fryer, London College of Printing (United Kingdom)
Tony Johnson, London College of Printing (United Kingdom)

Published in SPIE Proceedings Vol. 3963:
Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts V
Reiner Eschbach; Gabriel G. Marcu, Editor(s)

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