目前市面上的平板電腦、智慧型手機、個人行動助理、數位相機、以及其他的手持式裝置都是靠電池來提供電力。然而，電池的技術發展卻遠落後於半導體以及應用軟體的效能成長。目前的手持式裝置更以輕、薄、短、小做為設計導向，而電池本身必須同時考慮電池容量和體積。因此，電池的長效性發展通常無法完全解決裝置蓄電量不足的問題。

目前針對可攜裝置的功率節省技術可以分為低耗能積體電路設計、顯示卡與螢幕控制器的控制界面設計、以及背光控制三個種類。低功率積體電路技術是以時脈閘控、電源閘控、和動態電源頻率調整等方式來減少耗電量。顯示卡與螢幕控制器的控制界面設計是減少訊號傳輸的串音干擾和其他訊號延遲來避免額外的功率消耗。背光控制技術則是直接將顯示器需要使用背光進行節能設計。相較於成熟的低功率積體電路和匯流排編解碼設計，背光控制技術仍然具備十分重大的發展性。

本研究突破以往低功率技術只能依賴IC設計和匯流排編解碼的限制，並發展出一種新的背光控制技術來完成低功率顯示系統設計，同時輔以背光補償技術來增強顯示效果。本研究提出的背光控制與補償技術同時依據影像處理的統計資料做計算，因此具備背光調降和影像補償之間的比例性。經由電路功率消耗的實際量測與視覺檢驗兩種測試指出，本論文提出的方法能夠更節能地呈現影像的顯示效果。

Batteries are the source of electric power for many portable devices, such as Tablet PC, smart phone, Personal Digital Assistant (PDA), and digital camera. As weight, thickness, length, and size are four directions of developing portable devices, lightweight is also considered natural for designing batteries. In contrast with the development of semiconductor and applicable software, the technique of batteries is scientifically backward. Therefore, the current techniques of batteries are still hard to deal with the mentioned problems.

In general, for portable devices, low power techniques can be developed by integrated circuit (IC) design, low-power digital/analog interface between the graphics controller and the LCD controller, and backlight control for displaying. Low power IC focuses on the efficiency of DC/AC power inverters, the reduction of the working voltage and frequency, and the limitation of unnecessary power consumption in either idle mode or unused circuits. The low-power digital/analog interface scheme puts emphasis on the concurrent reduction of power consumption, noise, and delay time for the switching traffic. Color thin-film transistor (TFT) liquid crystal displays (LCDs) are equipped to many consumer products, while the backlight control is contributory to lower the power consumption for display systems.

As the IC technique and bus codec are ripe for the low power issue, backlight control technique is still developing toward for the multimedia application.
Therefore, this thesis highlights the backlight power consumption and compensates for the degraded quality of the image due to the scaled LCDs. The proposed method uses image processing algorithm to adjust power, while the related statistics are further included to dynamically compensate the image according to the original probability density. In other words, the balance between backlight reduction and image compensation is achieved according to the content of the displayed image. Experimental results demonstrate that the proposed method can reduce the power consumption of the display system, while the image can be enhanced to effectively present the visual effect.

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