A Method for Evaluation of the Font Definition Quality of eBook Readers

A method for evaluating the font displaying definition quality of eBook reader is presented here. Based on the characteristic of the spectral refection property of eBook surface, the spectral energy distribution of illumination, as well as the spectral response attribute of the human eye´s vision, the luminance contrast C_L between the white and blank display states and the white luminance Y_W of eBooks were defined and determined. By a psychophysical experiment conducted with 12 eBook readers on the market, an index Q_C used for giving their font showing definition performance was derived and investigated. Our experiment results showed that the index Q_C was correlated with not only C_L, but also Fw, and it could be well used for predicting the perceived eBooks´ font definitions when a linear transform from CL, and Fw was used. Besides, the CLELAB chroma C^* _ab was used for indicating the departure from the neutral color of the eBook background white. It was demonstrated that the reading easiness feeling would get worse as the C^* _ab increase, and C^* _ab values bigger than 6 could lead to distinct uneasiness of reading.