Reading rate legibility tests were conducted to provide data relating human performance to changes in the complex spatial frequencies of displayed alphanumerics resulting from changes in display focus or modulation transfer function. Human performance is thus quantized both with measured display parameters and the corresponding behavior of spatial frequency distributions of the displayed characters. A Sony Trinitron CRT monitor was used which exhibits aliasing in the same spatial frequency domain used to represent the alphanumerics. For alphanumerics subtending 0.3 degrees, the reading rate data exhibited asymptotic behavior at about 190 characters per minute thus indicating a critical bandwidth for legibility of about 2 cycles per character. Also, characteristic spatial frequency distributions were found to occur at this critical bandwidth. Despite the aliasing due to the Trinitron's aperture grille, the results were similar to those found with a monochrome CRT. These observations have profound effects on specifying resolution requirements for displaying text on CRT displays.

Date Published: 8 September 1993
PDF: 8 pages
Proc. SPIE 1913, Human Vision, Visual Processing, and Digital Display IV, (8 September 1993); doi: 10.1117/12.152698

Published in SPIE Proceedings Vol. 1913:
Human Vision, Visual Processing, and Digital Display IV
Jan P. Allebach; Bernice E. Rogowitz, Editor(s)