Quantification of image quality for color electronic paper

We have quantified the image quality of color electronic paper (e-paper) by subjective evaluations and clarified the requirements for improving the image quality. In the color e-paper field, various display types have been developed with the focus on improving the display performances or manufacture costs. However, color e-papers are still under development, and the image quality is not sufficient when compared with printed papers, photographs and conventional displays. With respect to the image quality of color e-paper in the future, it is very significant to clarify how reflectance, contrast ratio, National Television System Committee (NTSC) ratio, and other factors affect the image quality. Therefore, we have quantified the image quality factors such as color reproduction, tone reproduction, and surface texture. From our experimental results, we could clarify the significant factors and the practical range of image quality of color e-paper. For instance, both the reflectance of approximately 30% or higher, contrast ratio of approximately 8:1 or higher, and NTSC ratio of 20% or higher are the requirements for obtaining subjective evaluation score that is equivalent to that of newspapers, which are read very widely.