摘要
随着计算机使用的普及,用计算机制作的电子幻灯片已成为从事各行各业人员常用工具。但是,在应用中经常出现投影仪显示色彩与在制作时显示器看到的彩色不同,甚至产生很大的差别。从显示器到投影仪这是一个跨媒介颜色再现问题,以往处理颜色再现问题通常都要用到各式光学仪器,这在实际应用中不太现实。本文拟采用人眼视觉匹配的简单方法,通过对投影仪校正来达到实现颜色再现的目的。具体完成的研究工作包括:
(1)对满足相加性原理的时间独立性、时间稳定性、空间独立性和色品恒常性分别进行了测试研究,在此基础上研究了投影仪的特性化,分别用GOG和S模型(包括多项式、傅里叶和正弦逼近这三种方法)进行了拟合。并对这几种方法拟合效果进行了色差比较,结果表明S模型具有明显较小的色差。
(2)采用视觉匹配几块颜色,由CIELAB色空间色貌匹配获得显示器到投影仪变换矩阵。对Sony-G520 CRT显示器和SONY VPL-CX5 LCD投影仪进行实验,视觉匹配九块颜色,获得该显示器和投影仪间变换矩阵。安排4名实验者进行了主观评价,结果是校正后与未校正相比有很大改进,改进比例达87.5%。同时,对30个色块的校正效果进行了主观和客观评价,计算了未校正和校正后的色差,未校正平均色差为16.78ΔE_(ab)~*,校正后平均色差为3.51ΔE_(ab)~*,最大和最小色差由校正前的28.94ΔE_(ab)~*、4.35ΔE_(ab)~*下降到16.51ΔE_(ab)~*、0.64ΔE_(ab)~*,主观评价和客观评价取得了一致。
It become prevail that computer slides are displayed by a desktop projector.It is often happened that the projected color by the projector looks different from the color on the computer screen.The color reproduction from computer display to projector belongs to cross-media research field.It is not practical using optical instrument to implement the reproduction.In this paper,a novel method of color reproduction from computer display to desktop LCD projector was presented.The studies in the paper include:
(1) Additivity on projector including tone characteristics,color tracking characteristics,spatial non-uniformity and spatial independence was tested respectively.The GOG and "S" model was used to fit the projector color characteristics.The result shows the color difference of "S" model was little.
(2) The paper presented a novel method of the color reproduction from desktop displays to projectors via visual matching.The model was based on visual matching 9 color patches between a display and a projector.The effects of the method to improve color reproduction were tested for 30 samples by visual and color difference evaluations.The subjective assessment of four experimenters shows that the calibrated average color difference is improved considerably by 87.5%.The maximum, minimum and average color differences between the displayed colors and the projected ones uncorrected and corrected changed from 28.94,4.35,16.78 to 16.51, 0.64,3.51△E_(ab)~* units respectively,which were consistent with the results of visual evaluation.
引文
[1]TC8-01:CIE Publication 159:2004,A Colour Appearance Model for Colour Management Systems:CIECAM02,2004
[2]C.J.Chen,Mike Johnson.Fundamentals of scalable high resolution seamlessly tiled projection system.[C].Proceedings of SPIE Projection Displays Ⅶ,2001,4294:67-74.
[3]Mark Hereld,Ivan R.Judson,Rick L.Stevens.Tutorial:Introduction to Building Projection based Tiled Display Systems[J].IEEE Computer Graphics and Applications,2000,20(4):22-28
[4]Aditi Majumder.Properties of color variation across multi-projector displays[C].Proceedings of SID Eurodisplay,2002,817-810.
[5]Aditi Majumder.Contrast enhancement of multidisplays using human contrast sensitivity[C].Proceedings of IEEE International Conference on Computer Vision and Pattern Recognition,2005,:377-382.
[6]Maureen C.Stone.Color Balancing Experimental Projection Displays[C].the 9th IS&T/SID Color Imaging Conference,2001,342-347.
[7]Bastani Behnam,Analysis of Colour Display Characteristics[D].M.Sc.Thesis,Simon Fraser University,2005.
[8]沈默,李海峰等.液晶投影显示色均匀性的快速测量及误差分析[J].浙江大学学报(工学版),2006,40(6):1101-1104.
[9]Morovic J.,Luo M.R.Calculating Medium and Image Gamut Boundaries for Gamut Mapping[J].Color research and application,2000,25(6):394-401.
[10]Joni Orava,Timo Jaaskelainen and Jussi Parkkinen.Color Errors of Digital Cameras[J].Col.Res.Appl,2004,29(3):218-221.
[11]CIE Publication 131-1998,The CIE 1997 Interim Colour Appearance Model(Simple Version),CIECAM97s,1998
[12]C.Li,M.R.Luo,R.W.Hunt.A revision of the CIECAM97s model[J].Col.Res.Appl.2000,25(5):260-266.
[13]Ingeborg Tastl,Miheer Bhachech,Nathan Moroney.ICC Color Management and CIECAM02,2005
[14]周新伦,柳健,刘华志.数字图像处理[M].北京:国防工业出版社,1986
[15]金中.显示技术在比拼中前进[J].电子产品世界.2007,12(1):44-50.
[16]田民波.电子显示[M].北京:清华大学出版社,2001
[17]山崎映一[日]著,马杰译.发光型显示[M].北京:科学出版社,2004
[18]谢毓章.液晶物理学[M].北京:科学出版社,1988
[19]李维提,郭强.液晶显示应用技术(第1版)[M].北京:电子工业出版社,2000
[20]F.J.Kahn.Projection Display Technologies for the New Millennium[J].Proceedings of SPIE,2001,3954:12-18.
[21]J.B.Sampsell.An Overview of the Digital Micro-mirror Deviee(DMD) and Its Application to Pro- jection Displays[C].1993 SID International Symposium Digest of Technical Papers,1993,24:1012-1019.
[22]韩景福.LCoS显示技术与LCoS背投[J].现代显示,2008,88:5-11.
[23]Kathy Kincade,Contributing Editor Cptode Ctryomic Applications Projection Displays laser based projectors target consumer market[J].Laser Focus World,December,2005.38(5):111-116.
[24]魏忠伦.基于激光显示的颜色复现的研究[D].中国科学院研究生院硕士论文,2004
[25]徐海松.颜色信息工程[M].杭州:浙江大学出版社,2005
[26]陈颖.液晶投影显示颜色均匀性的研究[D].浙江大学硕士学位论文,2005
[27]荆其诚,焦书兰,喻柏林等.色度学[M].北京:科学出版社,1979
[28]郭凌华.对标准色度学系统颜色空间的理解[J].包装工程,2003,24(2):13-16
[29]黄庆梅,赵达尊.不同色域映射算法视觉效果的一种评价方法[J].北京理工大学学报,2003,23(4):408-413.
[30]石俊生,云利军,杨健等.CRT显示器特性化精度及黑点的影响[J].光学学报,2007,27(2):371-376.
[31]R.S.Berns,M.E.Gorzynski,R.J.Motta.CRT colorimet ry.Part Ⅱ:Metrology[J].Col.Res.Appl,1993,18(5):315-325.
[32]黄庆梅,赵达尊.彩色复制中的色域映射[J].照明工程学报,2002,13(11):19-26.
[33]王淑真,刘真.彩色复制中的色域映射方法[J].北京印刷学院学报,2006,14(3):4-6.
[34]胡威捷,汤顺青,朱正芳.现代颜色技术原理及应用[M].北京:北京理工大学出版社,2007
[35]Maureen C.Stone,Color and brightness appearance issuesfor tiled displays[J].IEEE Computer Graphics and Applications,September/October,2001:168-176.
[36]沈默,李海峰等.液晶投影显示色均匀性的快速测量及误差分析[J].浙江大学学报(工学版),2006,40(6):1101-1104.
[37]E.Stupp,M.Brennesholtz.Projection Displays[M].New York:John Wiley & Sons,1999.
[38]Jean.Thomas,Jon Yngve Hardeberg,Pierre Gouton.Additivity BASED LC Display Characterisation [J].Displays,2000,20:179-194.
[39]魏永毅力.液晶电光非线性效应校正技术研究[D].浙江大学硕士学位论文,2005
[40]IEC 61966-6,Colour measurement and management in multimedia systems and equipment D Part 6:equipment used for digital image projection,Committee Draft,August 1998.
[41]David R.Wyble.Colorimetric Characterization Models for LCD and DLP Projectors[R].CIS Industrial Associatees May 12-13,2003.
[42]杨翔鹏.液晶彩色投影电视中色度学问题的研究[J].现代显示,1996,4:13-18.
[43]Karen M.Braun,Mark D.Fairchild.Viewing Techniques for Cross-Media Image Comparisions[J].Col.Res.Appl,1996,21(1):6-17.