Legibility of perceptually-tuned grayscale fonts

Perceptually-tuned grayscale fonts are generated from character outline descriptions by applying to them a set of modifications specifically conceived for strengthening thin character parts, obtaining well-contrasted bars and preserving important relationships between character shape parts. The present study aims at comparing the legibility of perceptually-tuned grayscale and bilevel display fonts at small and very small sizes ( 6, 8 and 10 pt). The study confirms the results of previous studies indicating that reading speed is to a large extent independent of the typography (bilevel or grayscale) and the font size. However, perceptually-tuned grayscale characters perform better than bilevel characters for an italic string search task in a meaningless text. Regarding the subjective preferences of the test subjects, perceptually-tuned grayscale fonts at 8 and 10 point sizes received a superior rating than bilevel fonts at the same sizes. 1. PERCEPTUALLY TUNED GRAYSCALE FONTS In order to improve the display of text on limited resolution computer displays, researchers have tried to trade-off the lack of spatial resolution for an increased number of intensity levels [1, 2, 3]. Especially with respect to typographic text display on resolution limited CRT and LCD display devices, it has been shown that using grayscale makes font dependent character features visible which disappear when displaying text with bilevel characters. Though they can more accurately render font differences, grayscale characters generated by filtering and resampling high-resolution bilevel master characters nevertheless look rather fuzzy.