The impact of color combinations on the legibility of a Web page text presented on CRT displays

Abstract

This paper describes the impact of color combinations on the legibility of a Web page text presented on a calibrated cathode ray tube display. Four hundred and sixty-eight participants tested the legibility of 56 color combinations, compounded of elementary Web safe colors, with a visual performance task. In the task, the participants were asked to identify 21 uppercase alphabetic characters, selected and presented in conformance with the Snellen chart. The number of correctly identified characters was recorded as objective-dependent measure for each color combination. The impacts of color combination, luminance contrast, color difference, and polarity on the legibility were studied. According to the analysis of variance test, color combinations significantly affected the number of correctly identified characters. The obtained results showed that more than 90-year-old Le Courier legibility table is not appropriate for integrative color computer displays. Consequently, a new legibility table is proposed. The influences of both luminance contrast and color difference were investigated by means of the logarithmic and the second-degree polynomial regression model. A second-degree polynomial model proved as appropriate describing the legibility in dependence of luminance contrast. A second-degree polynomial model and logarithmic model proved as appropriate describing the legibility in dependence of color difference. The analysis of influence of polarity on legibility showed that, generally, dark backgrounds lead to better results for colors with greatest luminance contrast.