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Proceedings Paper

Two-Dimensional Spatial Frequency Content And Confusions Among Dot Matrix Characters
Author(s): Michael E. Maddox
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Paper Abstract

A two-phase study was conducted which related the confusions among dot matrix characters to the two-dimensional spatial frequency similarity of these characters. During the first phase of the study, subjects were shown single alphanumeric characters from four different dot matrix fonts and five matrix size/character subtense combinations. Data from this phase of the research were analyzed in terms of both correctness and character confusion frequencies. The second phase of the study consisted of digitizing and analyzing all characters from two of the fonts used in the first phase. The fonts chosen represent the most and least confusable of the four, based on the performance data obtained. These characters were scanned photometrically using a computer-controlled X-Y stage and subjected to a 512 X 512 point fast Fourier transform (FFT). The Fourier coefficients were correlated for all possible character pairs within each font-matrix/character size cell. These correlations provided an objective similarity measure among characters based upon their 2-D spatial frequency spectra. In addition to the spatial frequency similarity measure, a simple digital Phi coefficient was calculated for each character pair. The final analysis performed in this study was the correlation of observed performance (confusions) with objective similarity measures (2-D spectra and Phi coefficients).

Paper Details

Date Published: 2 November 1979
PDF: 8 pages
Proc. SPIE 0199, Advances in Display Technology, (2 November 1979); doi: 10.1117/12.958048
Show Author Affiliations
Michael E. Maddox, Virginia Polytechnic Institute and State University (United States)


Published in SPIE Proceedings Vol. 0199:
Advances in Display Technology
John R. Parsons, Editor(s)

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