臺灣博碩士論文加值系統

現存色調重製的機制大多只用一張高動態範圍影像來做，由於細節及顏色資訊有限的關係,並沒有辦法有效地恢復出我們在拍攝場景所看到的細節及顏色印象。因此本篇研究發展了一個新穎的複合式色調重製系統，採用兩張影像作為輸入，一張是以低曝光值設定拍攝的影像用來補捉相片中亮部區域的細節和顏色資訊;而另一張是以高曝光值設定拍攝的影像用來補捉相片中暗部區域的細節和顏色資訊。所提出的系統以低曝光值影像做為基準影像、並參考高曝光值影像裡的資訊，這個系統執行了區域色調對應的模組以及區域顏色對應的模組: (1)藉由在每個像素所對應的局部區域(局部區域的半徑是藉由重複次數地圖而決定的，其中重複次數地圖又是經由基於直方圖的區域切割及數學型態學裡的侵蝕程序而來。) 中計算出每個像素的局部適合亮度，這個系統執行了關於像素的區域色調對應 來對低曝光值影像壓縮其亮度的範圍，以及增強其局部的對比。 (2)區域顏色對應被實施來捕捉高曝光值影像裡的較為精確的顏色資訊。最後藉由雙彎曲函數設計出的融合程序被執行，混合區域色調對應以及區域色彩對應的結果來產生輸出顯示結果。實驗結果指出這個系統能產生出高真實性高動態範圍場景的重製結果。

Many existing tone reproduction schemes are based on the use of a single high dynamic range (HDR) image and are therefore unable to accurately recover the local details and colors of the scene due to the limited information available. Accordingly, the current study develops a novel composite tone reproduction system which utilizes two images with different exposures to capture both the local details and color information of the low- and high-luminance regions of a scene. Based on the low-exposed image and consult the information of high-exposed image, this system implements the local tone mapping module and local color module: (1) By computing local adaptation luminance of each pixel within its local region, whose radius is determined by iteration map which is produced by histogram-based segmentation and morphological eroding process, this system implements the pixel-wise local tone mapping module to compress luminance range and enhance local contrast. (2) The local color mapping module is applied to capture the precise color information from the high-exposure image to the low-exposed image. Eventually, fusion process whose fusion weights are produced via double sigmoid function is implemented to mix the local tone mapping result and local color mapping result to produce output display result. Experimental results indicate that this system generate highly realistic reproductions of HDR scenes.

Chapter 1. Introduction 1
1.1. Motivation 1
1.2. Related Works 3
Chapter 2. Iteration Map Creation and Local Region Determination 5
2.1. Histogram-Based Segmentation by Entropy Theorem 5
2.2. Iteration Map Creation by Morphological Eroding Operation 7
Chapter 3. Tone Reproduction Modules 9
3.1. Luminance: Pixel-Wise Local Tone Mapping Module 9
3.2. Color: Pixel-Wise Local Color Mapping Module 14
3.3. Fusion of Tone Mapping and Color Mapping Results 17
Chapter 4. Acceleration Using Multi-Resolution Approach 19
4.1. Pixel-Wise Local Tone Mapping Using Multi-Resolution 19
4.2. Pixel-Wise Local Color Mapping Using Multi-Resolution 21
Chapter 5. Experimental Results 23
Chapter 6. Conclusions 30
References 31

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