臺灣博碩士論文加值系統

良好的影像品質包含以下三種特性：適當的明暗度、清楚的細節特徵與接近人眼認知的顏色。在不同光源下，人眼認知物體的顏色，並不會隨著外界光源變化而變化，此現象稱為色彩恆常性。若影像中的景物顏色不同於人眼認知時，稱此為色偏影像。本研究仿照人類視覺特性提出一個自動明暗調整演算法，先以全域型調整機制使影像有適當的明暗準位，再使用區域型調整機制增加影像區域特徵的可見度。影像經過此演算法處理後，達到色彩恆常性結果。
我們置入Gray world與White patch理論於所發展的演算法裡，並提出兩種光源估測評估方法，對兩組影像資料庫做估測誤差，與其他方法做比較。

Appropriate brightness, clear image details, and close to human perceived colors characterize a fine color image. However, an incorrect color appearance may occur due to different illumination. Humans can perceive constant color appearances of objects without affection of various illuminating conditions. This phenomenon is called chromatic adaptation or color constancy. The objective of this thesis is to develop an algorithm of image lightness adjustment and color balance by mimicking the mechanism of human vision. Global lightness adjustment produces an appropriate brightness level for a given image. Subsequent local lightness adaptation increases the visibility of image details. We Proposed an algorithm of automatic adjustment the image luminance to achieve color constancy. We have embedded both the gray world and the white patch color constancy theories in our algorithm. We also developed two methods in estimating the color of the light source. The performance of the Proposed algorithm was evaluated for two sets of image database, and it was also compared with other methods

目錄
誌謝 i
摘要 ii
Abstract iii
目錄 iv
圖目錄 vi
表目錄 ix
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機 4
1.3 研究方法 6
第二章 文獻回顧 7
2.1色彩恆常性 7
2.2 von Kries Chromatic-adaptation Model 8
2.3 Gray world assumption 9
2.4 Standard Deviation Weighted Gray World(SDWGW)[5] 11
2.5 Shade of Gray World[6][7] 13
2.6 General Gray World[6-8] 15
2.7 White patch approach 17
2.8 Maximal-RGB Value[10] 18
2.9 Maximal-RGB Value 5％[10] 19
2.10 Retinex 21
第三章 色彩恆常性架構 23
3.1參數調整 24
3.2.1調u值 25
3.1.2 調k值 28
3.2 明暗度調整機制 31
3.2.1 全域調整法 ( global ) 31
A. Gray world全域型準位調整 32
B. White patch全域型準位調整 33
3.2.2 Global降 36
3.2.3 區域調整法 ( local ) 38
第四章 估測誤差 43
4.1標準光源法 44
4.2 反射估測法 47
第五章 影像實驗結果 49
5.1 線性影像 50
5.1.1標準光源法 57
5.1.2反射法 61
5.2 sRGB影像 63
5.2.1標準光源法 67
第六章 結論與展望 70
文獻回顧 71

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