Effects of ambient illumination on text recognition for UI development

In this research, the effects of illumination intensity on character recognition performances has been assessed for LCDs. Measuring how the minimum acceptable contrast ratio in the content changes as the device is moved from an indoor office illumination to a (simulated) outdoor level. The data collected during the research has been applied to an evaluation tool to assess the performances of a colour combination under various lighting conditions. The underlying equation is made available for further development and improvement of light aware UI in mobile applications. The collected data points out how the W3C 7:1 contrast ratio threshold is not sufficient to ensure legibility during outdoor/mobile use. A value of 18:1 is the suggested guideline for the minimum W3C contrast ratio high illumination.