Effects of Ambient Illuminance and Luminance Contrast on Visual Comfort for Reading on a Mobile Device

Mobile phone reading is becoming increasingly popular. An experiment with twenty young observers was conducted to investigate visual comfort when reading on mobile phones at five different illuminance levels (0, 10, 100, 500, and 1000 lx). The text and background are available in seven achromatic colours of different lightness levels from 0–500 cd/m2, making up 42 combinations. Each observer evaluated the visual comfort of 50 combinations when reading text using the 6-category points method. It was discovered that observers preferred a grey background to a white or black background. And a lower lightness contrast produces the least visual comfort. Positive lightness contrast around 50 to consistently give visual comfort. When the ambient illuminance reaches 1000 lx, observers feel most visual comfort.