感知影像品質與驅動電流同時最佳化的多灰階電子紙半色調演算法

Halftoning Algorithm with Simultaneously Optimized Perceptual Image Quality and Drive Current for Multi-tonal E-papers

王馨誼(Hsin-I Wang)

指導教授 ： 黃乙白

國立交通大學/電機學院/光電工程系所/碩士(2019年)

摘要

至今，電子顯示器的應用與發展，反映在市場對顯示器的廣泛需求，舉凡是在各個領域都展現了不可或缺的重要性。而與LCD或OLED顯示器相比，不使用背光模組的反射式顯示器(EPD)更是漸邁入市場，其具有類紙質感以及陽光下可視的護眼效果，其中最著名的EPD以電子紙為代表。電子紙不只擁有反射式技術還擁有雙穩態的特色，使其能在完全沒有電源的狀態下繼續呈現畫面於螢幕中，反映了其極省電的特點，只在更換畫面時才有電力被消耗。現今，電子紙隨著色彩的需求，從黑白顯示面板朝向彩色面板前進，除了發展具有高飽和度與高反射率的彩色電子紙，如何在有限位元的彩色面板上顯示多灰階影像面臨了一大挑戰。因此，發展能呈現灰階影像並兼顧電子紙原先特色的技術，成為探討本研究的主要動機。
本研究設備以元太科技公司Spectra TM 三色電子紙為基礎，以有良好發展的半色調演算法去解決不能實現多灰階電子紙顯示的問題，並且成功得到相當高的影像品質。而本研究不只在於呈現多灰階影像，更考慮到基於此演算法延伸的影像耗電量是不容忽略的。因此，我們建立了電耗與影像品質對應的電流模型，並發展了能同時最佳化感知影像品質與驅動電流的多灰階電子紙半色調演算法。從研究結果中確實得到低電流消耗與高品質的影像，也如預期地呈現在電子紙顯示器上並兼顧電子紙的省電特色。本研究就的價值與重要性在未來也將能被廣泛應用，並進階發展多色階彩色電子紙，預計都能得到相同的效果。

關鍵字

電子紙 ； 半色調影像

並列摘要

To date, the application and development of displays reflected the need of the market, which are indispensable in all fields. Compared with LCD or OLED displays, reflective electrophoretic displays (EPD) that do not use backlight modules are gradually entering the market. They have paper-like texture and visible eye protection in sunlight. The most famous EPD is E-papers. It not only has reflective technology but also has the characteristics of bistable, so that it can continue to display on the screen without any power supply with the extremely power-saving feature. It means that the power loss happened only when changing the screen. Nowadays, with the demand for color, B&W E-papers are stepping toward chromatic solutions. In addition, color E-papers are stepping toward developing high saturation and high reflectivity. Meanwhile, how to display multi-tonal images on a finite-pixel device is facing great challenge. Therefore, how to present grayscale images and take into account the original features of E-papers simultaneously has become the main motivation for this study.
In our study, the Spectra TM three-pigment EPD form E Ink (1200 pixels X 1600 pixels, 20 cm x 28 cm) was used. We solved the problem that multi-tonal E-papers cannot be realized with a well-developed halftone algorithm, and successfully obtained a high image quality. Our research is not only about presenting grayscale images, but also considering that the image power consumption based on this algorithm is not negligible. Therefore, we have established a current model corresponding to power consumption and image content, and developed a multi-tonal E-papers halftoning algorithm that can simultaneously optimize the perceived image quality and drive current. From the research results, low current consumption and high quality images are obtained and presented on the E-papers as predicted. The results also meet the power-saving characteristics of the E-papers. The value and importance of this research can be widely applied in the future, and the development of multi-tonal color E-papers is expected to do the same effect.

並列關鍵字

E-papers ； Halftoning

參考文獻

Reference

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