彩色背光演算法應用於高動態範圍液晶顯示系統

Abstract

低功率與高畫質的顯示器，近年來已成為顯示器研發的主要趨勢。由於傳統顯示器設計，受限於背光系統與液晶之組合，無法有效降低暗態，進而影響其顯示對比之能力。因此最早是利用影像處理方法，解決在受限的顯示器上呈現高動態範圍的影像，現今業界已經研發出可呈現高動態範圍的顯示器，但其影像顯示品質與功率消耗表現仍未臻完善。本論文提出以現今高動態範圍顯示器的技術為基礎，進而使用分區調整三原色(紅色、藍色、綠色)的背光，使現有高動態顯示器的暗態能進一步被優化，讓顯示器能達到更好的對比能力，除此之外，此技術更能減少漏光的效應，使其達到更高的色彩飽和度，最終還能達到更節省功率消耗且維持住影像細節的目的。 由實驗結果可證明，此方法已成功的應用在37吋高動態範圍液晶顯示器，使其在高對比的影像對比度從20,000:1提升至40,000:1且畫面細節能被維持住，並有效的使色域從108% NTSC擴展到125% NTSC，且相對於傳統的液晶顯示器能降低50%的背光損耗。

Low power and high image quality have become the major trend of display research in recent years. The contrast ratio of conventional liquid crystal display is limited to the full-on backlight system. Traditionally, the solution is to perform image processing in the low dynamic range display. High dynamic range displays were proposed by adopting the local dimming LED backlight system. Although, it can display high contrast images, but can not optimize power consumption and image quality. In this thesis, we proposed the two color backlight algorithms, DCA and SCC, by controlling R, G, and B LEDs individually to optimize the traditional high dynamic range displays. This method could improve the contrast ratio by reducing dark state and enhance color saturation by reducing the effect of light leakage. Besides, it could reduce more power consumption and keep image details. This method has been demonstrated that color backlight algorithm implemented on a 37’’ high dynamic range liquid crystal display (HDR-LCD) TV can yield contrast ratio of ~40,000:1 with clear image details. Furthermore, the color gamut can be enlarged to 125% of NTSC and reduced 50% power consumption compared to full-on backlight.