近年來，平面液晶顯示器產業是目前國內蓬勃發展的製造業，也是國內最具有世界級競爭力的產業，然而在平面液晶顯示器，最常出現的瑕疵就是面板不均勻的現象，這種不均勻現象稱之為”Mura”，目前在檢測不均勻現象嚴重程度都是藉由人眼來檢測，不同的檢驗員對同一種不均勻現象的判定也會有所差異，所以平面液晶顯示器的供應商和顧客常常因為不均勻現象的定義不一致而有所衝突。
為了解決供應商與顧客間衝突，日本學者Y. Mori等人提出了亮度對比閾值和不均勻面積大小的迴歸方程式，並作為判斷不均勻現象嚴重程度的依據，但對於不均勻現象嚴重程度的判定，只考慮不均勻面積大小是不夠的，所以本研究除了探討不均勻面積大小對人眼對亮度對比閾值的影響之外，並加入目前最常出現的不均勻現象作為研究因子，例如：不同的檢測灰階背景、不均勻線的長度、周邊的不均勻現象以及檢測背景為全紅、全綠和全藍等因子。
從實驗結果得知，影響視覺對比閾值顯著的因子有不均勻的面積大小、不均勻出現的位置以及不同的檢測背景顏色，但亮不均以及暗不均並沒有顯著影響視覺對比閾值。不均勻面積的大小，影響視覺對比閾值比其他因子最為顯著，因此，本研究針對在不同位置下，建立視覺對比閾值與不均面積的迴歸方程式。綜合以上實驗結果，可作為平面顯示器產業在檢測不均勻現象的參考。

In recent years, the domestic industries of flat panel liquid crystal display have grown up rapidly, and were able to compete with other industries of the world. The defects of flat panel liquid crystal display were usually un-uniform, and the defects were called as “Mura”. There were many factors to cause Mura phenomenon. At present, the seriousness of Mura was defined by human eyes, and different operators defined the same Mura phenomenon with different meanings. For this reason, there have been many conflicts between the suppliers of flat panel liquid crystal display and customers.
In order to solve conflicts between supplier and customers, some researchers proposed a regression equation of luminance contrast threshold and size of Mura. However, only discussing relationship between Mura size and luminance contrast threshold was not enough to define the seriousness of Mura. In addition to the effect of Mura size on luminance contrast threshold, this study investigated the relationship between other factors and luminance contrast threshold. These factors were detection gray backgrounds, lengths of weak line, Mura position, and full screen (Red, Green, Blue) respectively.
Analysis of results showed that Mura size, Mura position, and different color backgrounds significantly affected visual contrast threshold. However, polarity did not significantly affect visual contrast threshold. In this study, it was found that Mura size was more important than other factors for visual contrast threshold. Therefore, this study applied the experimental data to develop regression equations of Mura size and visual contrast threshold under different Mura positions. The results of this study were expected to be references for inspection of LCD industries.

1. http://www.d-silence.com/
2. M. Menozzi, U. Näpflin, H. Krueger, “CRT versus LCD: a pilot study on visual performance and suitability of two display technologies for use in office work”, Displays 20, p3-10 (1999).
3. M. Menozzi, F. Lang, U. Näpflin, C. Zeller, H. Krueger, “CRT versus LCD: effects of refresh rate, display technology and background luminance in visual performance”, Displays 22, p79-85 (2001).
4. Don-Gyou Lee, Il-Ho Kim, Mun Cheol Jeong, Baek Keun Oh, Woo Yeol Kim, “Mura analysis method by using JND luminance and the SEMU definition”, IDW, p1467-1470 (2003).
5. VESA, “Flat Panel Display Measurements Standard”, Version 2.0, p78.
6. Y. Mori, K. Tanahashi, R. Yoshitake, S.Tsuji, “Extraction and evaluation of mura images in liquid crystal displays”, Algorithms and Systems for Optical Information Processing V,SPIE, p299-306(2001).
7. SEMI DRAFT DOCUMENT 3324 (2002).
8. “Definition of measurement index (SEMU) for luminance Mura in FPD image quality inspection.” SEMI D31-1102 (2002).
9. Y. Mori, K. Tanahashi, R. Yoshitake, S.Tsuji, “Quantitative evaluation of visual performance of liquid crystal displays”, Proceedings of the Algorithms and Systems for Optical Information Processing （The International Society for Optical Engineering）, SPIE, 4113, p242-249 (2000).
10. “Method and Apparatus for Detecting Mura Defects”, This application claims benefit of Provisional application Ser. No. 60/041, 908 filed Apr. 7, (1997).
11. “330-x Mura Defects” VESA, 1-15 (January 24, 2000).
12. William K. Pratt, Sunil S. Sawkar and Kevin O’Reilly, “Automatic blemish detection in liquid crystal flat panel displays”, SPIE Vol.3306, p2-13 (1998).
13. An-Hsiang Wang, Ming-Te Chen, “Effects of polarity and luminance contrast on visual performance and VDT display quality”, International Journal of Industrial Ergonomics 25, p415-421(2000).
14. Y.Y. Yeh, L. D. Silverstein, “Limits of Fusion and Depth Judgment in Stereoscopic Color Displays” Human Factors, Vol.32 (1), p45-60 (1990).
15. J. H. Krantz, L. D. Silverstein, Y.Y. Yeh, ”Visibility of Transmissive Liquid Crystal Displays under Dynamic Lighting Conditions” Human Factors, Vol.34 (5), p615-632 (1992).
16. T. G. Fiske, L. D. Silverstein, “Characterizations of Viewing-Angle-Dependent Colorimetric and Photometric Performance of Color LCDs,” SID, 565-568（1993）
17. Z. Zhu, J, Wu, “On the standardization of VDT’s proper and optimal contrast range”, Ergonomics Vol.33 (7), p925-932 (1990).
18. A. Dillon, “Reading from paper versus screens: a critical review of the empirical literature”, Ergonomics Vol.35 (10), p 1297-1326 (1992).
19. S. Saito, S. Taptagaporn, G. Salvendy, “Visual comfort in using different VDT screens”, International Journal of Human-Computer Interaction Vol.5 (4), p313-323 (1993).
20. H.L. Snyder, J.J. Decker, J.C. Lloyd, C. Dye, “Effect of image polarity on VDT task performance”, Proceedings of the Human Factors Society 34th Annual Meeting, Santa Monica, CA, p1447-1451 (1990).
21. K.T. Mullen, “The contrast sensitivity of human colour vision to red-green and blue- yellow chromatic gratings”, Journal of Physiology 359, p381-400 (1985).
22. R. Näsänen, H. Ojanpää, I. Kojo, “Effect of stimulus contrast on performance and eye movements in visual search”, Vision Research 41, p1817-1824 (2001).
23. Y. Mori, R. Yoshitake, Tohru Tamura, “Evaluation and discrimination method of “mura” in liquid crystal displays by just noticeable difference observation”, Proceedings of SPIE, Vol. 4902, p715-720 (2002).
24. Ehrenstein WH, Ehrenstein A, “Psychophysical methods” In: Windhorst U, Johansson H (eds): Modern techniques in neuroscience research, pp 1211-1241. Berlin: Springer-Verlag (1999).
25. Farell and Pelli, “Psychophysical methods, or how to measure a threshold, and why”, Carpenter and Robson Vision Research-a practical guide to laboratory methods. Oxford Univ. (1998).
26. B. Watson, “QUEST : A Bayesian adaptive psychometric method”, Perception & Psychophysics, Vol. 33(2), p113-120 (1983).
27. 馬秀蘭，吳德邦 著, “統計學/以SPSS for Windows為例”，出版社：新文京開發。(2002)
28. T. Tamura, K. Tanaka, M. Baba, M. Suzuki and T. Furuhata, “Just Noticeable Difference(JND) Contrast of “Mura” in LCDs on the Five Background Luminance Levels”, International Display Workshop, Japan (2005).
29. G. Wyszecki, W. S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, John Wiley &Sons, New York (1982).
30. D. L. MacAdam, “Specification of Small Chromaticity Differences”, Journal of the Optical Society of America, Vol. 33(2), p18-26 (Jan 1943).
31. Cushman, W.H. “Reading from microfiche, a VDT, and the printed page: subjective fatigue and performance.” Human Factors Vol.28 (1), p63-73 (1986.).
32. Shieh, K.K., Chen, M.T., “Effects of screen color combination, work-break schedule, and workspace on VDT viewing distance.” International Journal of Industrial Ergonomics, 20, p11-18 (1997