Integrating photometric calibration with adaptive image halftoning for electrophoretic displays

The electrophoretic display (EPD) has become the main solution to electronic papers, but there are several limitations when it is being driven. First of all, the optical response curve of the EPD is nonlinear and temperature sensitive. In addition, the number of gray levels that can be displayed is also quite limited. The image quality is unsatisfactory if the images shown on the panel are not preprocessed to increase the number of visual gray levels and compensate the characteristics of the EPD. In this paper, we present an integrated image tool to automatically estimate the reflectance function curves under different ambient temperatures, perform adaptive image halftoning to improve visual quality, and calibrate the image to compensate the nonlinear response of EPD. The proposed approach has been verified on practical EPD panels and promising results have been achieved.