整合即時半色調影像處理以及區域影像更新之電泳顯示控制器系統設計

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2010

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電泳顯示器具有不易變化的反射率與雙穩態的特性,因此被視為是電子紙亦或電子閱讀器的最佳解決方案。在不同使用條件下的電子紙,其所需的畫面解析度、速度與對比度都不盡相同,因此電子紙設計者需採用各種電泳材料與不同解析度的主動式矩陣背板來設計出各類型的電子紙,甚者,驅動波型也需因應於各種不同的層面,並與環境溫度進行校調。為了設計出簡易的驅動波型對照表設計架構,因而設計出一個可應用於主動式矩陣電泳顯示的控制器,此控制器可以提供區域影像更新,並可以即時對影像做半色調的處理。電泳顯示控制器已在FPGA上實現,其效能也在許多電泳顯示器測試平台上獲得驗證。 另一方面,由於電泳顯示器僅能達到16色灰階的解析度,若直接顯示其畫面品質很難被大眾所接受,因此我們針對半色調演算法進行探討,並開發出一套影像處理工具,將影像作對比強化與半色調的處理後,影像的視覺品質顯著的提升,藉以克服低解析度的缺點。
Electrophoretic displays (EPD) have become the main solution to electronic paper because of its invariably reflective and bistable properties. With different requirements of display resolution, speed, and contrast ratio, E-paper designers may adopt different types of electrophoretic material and active matrix backplane for building the system. The driving waveforms should be also customized for accommodating different application specifications and environment temperature. In this paper, we present a configurable EPD controller which can support various application specifications. In addition to providing a new architecture of compacted waveform lookup tables, the controller supports partial image update and integrates a real-time halftoning engine for improving image quality. The design has been implemented on an FPGA and tested with several real EPDs. On the other hand, due to the electrophoretic display has only 16 gray scales resolution, if direct display an image on EPD, the image quality is difficult to be accepted by the user. We focused on the halftoning algorithm and developed an image processing tool with image contrast enhancement and halftoning processing, the visual quality has significant improved and overcame the weakness of low resolution.

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雙穩態顯示器, 驅動波型, 電泳顯示器, 電子紙, Bistable display driver, driving waveform, electrophoretic display (EPD), electronic paper

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