Predicting the Readability of Transparent Text

Text readability was measured for two types of transparent text (additive and multiplicative) at two contrast levels (0.3 and 0.45) on three background textures (culture, wave, plain), and it was measured for five levels of low text contrast (0.1, 0.15, 0.2, 0.25, 0.3) on plain backgrounds. For the transparent text, reading search times were longer for additive transparency, the low contrast, and the culture then the wave and then the plain background. For the low contrast experiment the 0.1 contrast level led to significantly slower search times when compared to all other contrast levels. When there were background textures a masking index that combined text contrast and background RMS contrast predicted search times much better than either measure alone. When the masking was adjusted to include the text pixels as well as the background pixels in computations of mean luminance and contrast variability, predictability improved further