低液晶螢幕背光下之影像增強技術

Abstract

保持不同環境光下的影像可視性一直是可攜式電子設備在設計上所面臨的問題。本篇研究針對電子設備所提供之背光亮度小於環境光亮度造成影像無法清楚呈現的問題提出了有效的影像增強演算法。該演算法的訣竅主要在於將影像的亮度控制在人眼可辨識的範圍。在影像亮度範圍壓縮的過程中，我們發現相較於原本較暗區域儘量維持原本較亮區域的對比度的方法能有效的保留影像的感知對比度。在實踐此方法的過程中，我們利用JND的理論將影像分成亮度和感知強度兩個圖層。接著我們將增加亮度層中較暗部分的亮度已達到增加整張影像可視度之目標。實驗結果證實，本篇研究所提出之方法可有效的運作於背光10%的實際環境下。

Maintaining image quality under various lighting conditions is critical to portable multimedia devices. In this thesis, an image enhancement algorithm is proposed to deal with extremely dim LCD backlight under which the image often becomes imperceptible. The crux of our idea is to keep the detail content of the image in the visible luminance range. To do that, just noticeable difference (JND) theory is used to form a two-layer image decomposition architecture for extracting the details, and a boosting scheme is applied to the details that are in the low intensity luminance regions of the image. Experimental results have shown the superiority of the proposed algorithm.