Thai typefaces (Part 2): Criticism based on legibility test of some isolated characters

Background According to the assumptions of our previous study, we qualitatively tested the tolerance of Thai characters under blurred conditions, Gaussian blur. Firstly, 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. This study was conducted to prove the assumptions of the previous study based on quantitative research, as a pilot study. Methods We chose some characters which were expected to have advantages and disadvantages regarding visibility and legibility. The selected characters were subjected to blurred conditions and administered to participants for investigating the case of Thai legibility. Results We found the simulated conditions revealed many problems on the visibility and the legibility matters of Thai characters; however, these findings led to ideas and possible solutions, which may provide assistance for the approach to designing a Thai typeface that has high legibility and visibility. Conclusions In order to improve some Thai characters with high legibility and visibility, the key features may be involved to 5 features that should be considered to develop Thai UD Typeface consist of; 1) type anatomy; 2) character width; 3) character shape; 4) stroke shapes and; 5) terminal aspect.