臺灣博碩士論文加值系統

高動態範圍影像(High Dynamic Range Images, HDR image)提供?較以往?位影像?高的動態範圍，因此較能把真實景像準確地重現。但目前一般的低動態範圍(Low Dynamic Range, LDR)顯示器能顯示的動態範圍則遠低於高動態範圍影像。為了使用一般的顯示器亦能顯示高動態範圍影像的細節及效果，因此有許多色調映對(Tone Mapping)演算法將高動態範圍影像中龐大的動態範圍加以壓縮，以便對應至低動態範圍之一般顯示器來做顯示。但在壓縮的過程中，由於動態範圍被大幅地縮小，使得輸出影像在視覺的對比?、清晰度及色彩之飽和度上受到影響，因此尚有研究的必要性。
本?文在適應性對數映射演算法(Adaptive Logarithmic Mapping Algorithm)上結合雙向濾波器(bilateral filter)之原理，提出了一個使用在高動態範圍影像顯示上基於雙向濾波器和對比調整之色調再生法，利用雙向濾波器(bilateral filter)能將影像亮度值分離成基層(base layer)和細節層(detail layer)之原理，有效保留影像中的細節資訊並能夠調整其整體對比亮度，以便有效改善僅使用適應性對映對法轉換之影像細節部份會因過亮或過暗而不明顯的問題。
經實驗之影像輸出結果顯示，本?文所提出之演算法能適用於大多?HDR輸入影像之轉換，且在LDR之顯示器上能輸出有很好的視覺效果的影像。較之於其他演算法，此方法之輸出影像較?以及較暗處的細節與對比皆有?好的表現，可保有原始影像的視覺觀感，並能夠強化輸出影像的色彩效果，因此增加?LDR影像在視覺上的整體效果。

High dynamic range (HDR) images provide larger dynamic range than traditional digital images, and they aim to rebuild the luminance of real world precisely. However, the dynamic range of traditional low dynamic range (LDR) monitors is much smaller than HDR images. In order to display the visual effect of HDR in traditional monitors , many tone mapping techniques were used to compress HDR to LDR. By tone reproduction techniques, the visual effect of HDR can be displayed correctly in traditional monitors . During the compression process, it would have impact on the visual contrast ,detail and saturated color because that the dynamic range is reduced largely. Therefore, it is necessary to survey on this topic.
In this work, we propose a tone reproduction method that called“A Tone Reproduction Method Based on Bilateral Filtering and Local Contrast Adjustment for HDR Image Display” and it is based on adaptive logarithmic mapping algorithm and bilateral filter. In our method, we use bilateral filter to separate image luminance to base layer and detail layer ,and make it keep the image detail and work fine on global contrast adjustment. In our method, it has great improvement on the detail effect that images may lose their detail effect after using adaptive logarithmic mapping algorithm.
Experiment results show our tone reproduction algorithm can deal with most input of HDR images and works well. The output of LDR images also work fine on detail effect in LDR monitors. Our method compares with other algorithms , and it also performs well in brighter and darker areas of output images, details of those areas are both clear. Therefore, our algorithm has great improvement on visual effect.

第一章 緒論----------------------------------------------1
第二章 相關背景------------------------------------------5
2.1影像之對?映射----------------------------------------5
2.2適應性對?映射演算法----------------------------------7
2.3用於高動態範圍顯示上的快速雙向?波法------------------9
2.4局部對比強化-----------------------------------------12
第三章 以基於雙向濾波器和對比調整之色調再生------------16
3.1影像色彩空間轉換-------------------------------------17
3.2適應性對數轉換---------------------------------------18
3.3局部對比調整-----------------------------------------21
3.4細節強化---------------------------------------------31
3.5影像色彩重組-----------------------------------------38
第四章 實驗結果與討論-----------------------------------41
4.1實驗相關配備及環境-----------------------------------41
4.2本論文所提出之演算法與其他演算法之比較---------------42
4.3本論文所提出之演算法與其他演算法之局部顯示比較-------55
4.4本論文方法運用在傳統陰極射線管顯示器的輸出結果-------62
第五章 結?與未?展望-----------------------------------66
參考文獻------------------------------------------------68

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