Size and contrast threshold for legibility

How to use this database

Outlines

This database can estimate the legible font size of a letter and a digit by setting design parameters of the display character (font, characters, and luminance contrast between a character and background) and their conditions of use (user’s age and viewing distance). In addition, this database can estimate the legible luminance contrast between a character and background by setting design parameters of the display characters (font, characters, and size) and their conditions of use. The estimated results are not enough applicable for people with visual impairments.

Input Parameters and Estimation Procedures

(A) Age: Choose “young (18–28 years old)” or “elderly (60–77 years old)” from a pull-down menu.
(B) Visual distance: Choose the viewing distance.
[Only “70 cm” is available now.]
(C) Font: Choose “MS Gothic” or “MS Mincho” typeface from a pull-down menu.
(D) Visual complexity (Type of Characters): Choose “Complex” (e.g. Kanji) or “Simple”
(e.g. Alphabet, Digit, or Angular Japanese syllable).
(E) Legibility level: Select a level of legibility to estimate the applicable size and contrast.
[Only “Threshold” (an average threshold of a legible size or contrast) is available now.]
(F) Positive / Negative: Choose “Positive” (luminance of a character is darker than the background) or “Negative”
(luminance of a character is brighter than the background).
(G) Specification parameter: Select parameters to leave it open for estimation.
[Choose “Size”, “Contrast” or “None”.]
(H) Value of the specified parameter: Selection is active only when “Size” or “Contrast” is selected in the specification parameter (G). If the specification parameter (G) is “Size”, then choose the value of size from “8”, “12”, “18”, “28”, “40”, “80”, and “160” point in DTP unit. If the specification parameter (G) is “Contrast”, then choose the value of luminance contrast from “25” and “100” percent in Michelson contrast.
(I) Estimation button: To activate the estimation button, fill in (A)–(H). Click the estimation button, so that the results of applicable size or contrast are shown in the right column.