Thai typefaces (Part 1): Assumption on visibility and legibility problems

Background Regarding the growing elderly population, which several countries are experiencing right now, various typeface designs have been developed to address the need for increased legibility and visibility. Certainly, common factors that affect the well-being of the elderly are related to visual acuity. The universal design fonts (UD fonts) developed in Japan are regarded as a role model for the development of highly legible and visible Thai typefaces. As Thailand's society matures, the concern for creating a Thai UD font based on human-centered design is ideal for the purpose of supporting elderly people as well as people with amblyopia and low vision Methods As the first step to developing a Thai UD font, as a preliminary study, we qualitatively tested the tolerance of Thai characters under blurred conditions. We used the fifty Thai conventional text fonts in the boundary of 'The Table of Thai Character's Relationship' in the same character heights as stimuli. The stimuli simulated the visual acuity of people with poor vision at different blur levels. Results From the tests, we have established the expected Thai confused pairs, as the assumptions. We found the simulated condition revealed many problems with the visibility and the legibility matters of Thai Characters, as the assumptions; however, these findings led to ideas and possible solutions, which may provide assistance for the approach to designing the first Thai UD font. Conclusions After the simulated blurring was administered to the Thai conventional text fonts, visibility problems gave rise to discovering legibility issues - and consequently - an escalation of confused pairs. Therefore, the approach to developing the glyph of Thai UD fonts should apply two principles, 'EMPHASIS' and 'REDUCTION' (and others), for overall improved visibility and legibility.