高動態範圍液晶顯示系統之背光優化演算法

Abstract

傳統液晶顯示器之對比，受限於背光系統與液晶之配合，無法降低其暗態，進而影響其顯示對比之能力。過去係利用影像處理之方法，解決在受限的輸出元件上顯示高動態範圍影像的問題。現今業界已研發出可顯示高動態範圍之顯示器，不需再受限於液晶低動態範圍之顯示能力，但其影像顯示品質仍未臻完善。本論文提出一種背光處理方法，利用優化背光調整曲線進而動態調變背光信號，可使高動態範圍液晶顯示器之對比度提升且畫面細節亦能維持，使人眼觀賞之感覺更為舒適，得到系統最佳化之顯示效果。由實驗結果證實此方法可將37吋高動態範圍顯示器之畫面對比度從1,200:1提升至20,000:1，畫面失真度減少，並保持面板之最大亮度，且可有效降低背光之功率消耗。

The contrast ratio of conventional liquid crystal display is limited due to the full-on backlight system. Traditionally, the solution is to perform image processing in the low dynamic range display. However, the contrast is still limited by the light leakage of liquid crystals. High dynamic range displays was proposed by adopting the local dimming LED backlight system. Although it can display high contrast images, but still not optimized. This thesis proposes the concept of backlight modulation curve (Inverse of Mapping Function- IMF) in the high dynamic range displays to get not only high global contrast ratio, but also clear image details. It has been proven that IMF method implemented on a 37” high dynamic range liquid crystal display (HDR-LCD) can yield contrast ~20,000:1 with low image distortion, high luminance, and low power consumption.