| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 99 === The aim of this research was to evaluate the performance of a reflective black-and-white e-book using electronic ink and a colour reflective e-book using Cholesteric Liquid Crystal under different illumination conditions. Furthermore, their performance was analyzed in comparison with hardcopies outputted by inkjet printers.
The physical measurement was conducted to specify the characteristics of reflective e-books in five measurement items including contrast ratio, chromaticity of peak white and primary colours, tone response curve, and luminous non-uniformity.
A psychophysical experiment was carried out to evaluate the performance of the test e-books in terms of image quality and readability. The experiment evaluated the following four independent variables: illumination, display medium, contrast, and resolution. The illumination conditions included three-primary multi-colour LEDs, five- primary multi-colour LEDs, a white LED driven with alternating current, and a CWF. The illuminace level and correlated colour temperature of all illuminations were set to the same, 800 lux and 3600 K. Hardcopies were printed out at 3 levels of contrast (high contrast, middle contrast, low contrast). The resolutions of e-books and hardcopies were set to 167 dpi and 600 dpi, respectively. The display mediums included two kinds of reflective e-books (black-and-white type and colour type), and two kinds of papers for hardcopies, coated (photo-glossy) and uncoated paper (matte). Participants followed the instructions to assess all of the display medium conditions under four illumination conditions.
According to the evaluated results, the display medium conditions had a statistically significant effect on image quality, text quality and perceived text resolution. The statistical difference was, however, due to a significantly higher perceived quality of coated paper with high contrast. Illuminations had no significant effect on the performance of all display medium conditions except colour image quality. The results showed that the ergonomic evaluations of black-and-white and colour reflective e-books and their resolution settings were good enough to compete with office paper for reading. However, the current contrast still needs to be improved for both text reading and picture showing. Using LEDs to view a colour image on display media is at least as good, if not better than using traditional CWF.
|
|---|
