高動態範圍影像是利用多重曝光度的拍攝方法，把不同曝光程度的影像合併起來，因此高動態範圍影像的亮度(luminance)顯示範圍遠高於一般低動態範圍顯示器，如果把一張高動態範圍影像直接由一般顯示螢幕撥放，容易出現顯示上的問題，例如影像過曝或過暗等等。為了適當地把高動態範圍影像顯示在一般顯示螢幕上，常見的一種解決方法就是色調映射(tone mapping)，色調映射可以把高動態範圍影像的亮度壓縮成一般低動態範圍顯示器的亮度顯示範圍，而這是一個失真壓縮。一個好的色調映射必須真實地還原原始場景的亮度，而不是破壞影像來得到一張誇大，求鮮豔的影像。本論文提出一個兩階段的色調映射方法，第一階段我們利用Naka-Rushton方程式來實作一個基於知覺的全域性色調映射方法，並且在色調映射的過程中特別保留住了亮處部份的細節資訊。而第二階段我們分析了一些細部增強的演算法，為了避免光暈(halos)產生以及降低失真率，我們選擇了Guided Image Filter去實作我們的第二階段。最後我們以一個通過物理實驗驗證的公制標準來評估我們做完色調映射後的失真率，與過去的方法比較，本論文不僅能更清楚地保留住亮處細節而且在失真率的降低上也表現得更為出色。

High-Dynamic Range images have a span widely radiances, so the HDR images are not displayable in a regular Low-Dynamic Range monitors. The common solution of this problem is called Tone Mapping. Tone mapping can compress the HDR images into the LDR images with distortion. A good tone mapping operator should reproduce the original scene realistically instead of damaging the original images to obtain the exaggerate results. We propose our method in two stages. The first stage is a global perceptual-based tone mapping operator that implements the Naka-Rushton equation to do visual adaptation and preserves the detail of the brightness region. The second stage is to implement the Guided Image Filter to analyze local detail enhancement methods in order to avoid halos artifact and reduce the distortion rate efficiently. Focusing on distortion, we evaluate both two stages of our method with metric validated by psychophysical experiments, the distortion rate of two stages outperform the state of the art.

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