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標題: | 應用於有機發光體顯示器之影像估計與影像補償技術 The Technique of Image Estimation and Image Compensation for AMOLED Display Application |
作者: | Hsueh-Yen Yang 楊學炎 |
指導教授: | 曹恆偉 |
關鍵字: | 有機發光體顯示器,數位節能,子像素排列, AMOLED,digial power saving,sub-pixel rendering, |
出版年 : | 2017 |
學位: | 博士 |
摘要: | 由於有機發光體顯示器可提供較液晶顯示器更好的顯示品質,因為電流驅動加上自發光元件使其發光反應速度更快,利用軟性基板的替用可製作可撓式面板,提供許多現今主流液晶顯示器不可能的應用,進而成為現今最先進的顯示技術,因為有機發光體顯示器存在材料特性本身造成的問題,於是需應用一些電路及影像處理技術來改善,如有機發光體是電流驅動的自發光材料,其各子像素發光強度取決於電流大小,如果各子像素存在製程偏差而使VTH或K值不均時,可能就造成面板顯示均勻度不足,也就是MURA過於明顯,於是有了多TFT子像素驅動電路,為的就是消除VTH或其他電流影響因子,使顯示均勻度得以改善,所以有機發光體顯示器的對於電路設計的面積有一定大小的需求,使得它在高解析度的實現能力相較液晶顯示器的設計來得有所限制,於是應用子像素排列技術提高顯示解析度,在本論文提出樣式評估(pattern estimation)及像素補償(Pixel compensation)的演算方式,以樣式評估找出該排列可能造成顯示不正常的影像邊緣特徵,利用邊界編碼的方式描述,再結合像素補償以相鄰子像素借色方式改善,二者相輔相成提供該應用相當大的可調適性以及硬體實現的演算方法,在顯示效果的比較上,其算法在相近的功耗條件下相較於先前算法提供更佳的表現;另外因為長時間過亮的顯示內容可能造成有機發光材料壽命減少,於是利用亮度調整的技術達到節能的需求,亦可使有機發光材料壽命延長,以分析輸入影像的內容來調控亮度,因為有機發光顯示不具背光元件而採用數位節能方式,本論文提出區域亮度評估(Luminance estimation)的算法及硬體架構,並結合色彩與亮度共同修補的方式完成區域亮度的調控,利用不同的調控因子改變亮度減少功耗,但仍可維持大部份影像原有的表現,在顯示效果的比較上,其算法相較於先前算法提供更大的節能範圍,並且考量亮度保護的設計使原始影像特徵得以維持。 AMOLED display provides higher color saturation and superior contrast than AMLCD. An OLED is self-emitting and a current-driven device so as to perform faster response time than liquid crystal. The flexibility of AMOLED is possibly implemented by the utilization of polyimide (PI) backplane. These characteristics lead advance display application so that AMOLED become popular display technology in recent. Because the process problem of AMOLED display is existed, specific design of pixel driving circuit and image processing is required to improve. Its display brightness is determined by the level of driving current through. Process variations in the manufacturing of the poly-crystalline silicon backplane often cause the difference of Vth (threshold voltage) and electron mobility among TFT’s. Some unexpected MURA effect will occur so as to develop internal compensation for improving the performance of panels. This layout area of this pixel circuit needs more and resists the implementation of high resolution application in AMOLED panel. Sub-pixel rendering is applied to reduce the number of sub-pixels in order to widen the pitch of pixel layout. In this paper, we propose the algorithm of pattern estimation and pixel compensation to implement it. The both functions are presented to detect where the pattern may cause abnormal display issues and improve it by specific low-pass filtering respectively. The methods can be combined to provide algorithmic flexibility. In experimental comparison, the proposed algorithm can provide better performance in display quality. Excessive current stressing may cause the lifetime reduction of OLED device so that brightness control is required to achieve the digital power saving. The digital power saving (DPS) techniques are implemented by adjusting image content to modify display brightness. The study will propose luminance estimation and color compensation to perform the modification of local brightness. The proposed algorithm presents more flexibility of DPS than current methods and considers brightness preservation to maintain image details. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60061 |
DOI: | 10.6342/NTU201603789 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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ntu-106-1.pdf 目前未授權公開取用 | 2.84 MB | Adobe PDF |
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