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1、CIE 80 89 = 9006345 0003784 858 ISBN 3 900 734 17 8 C O M M ISS I O N I NTER NAT I O NALE D E L C LAI RAG E INTERNATI ON AL COM M ISSION ON I LLUM INATION INTERNATIONALE BELEUCHTU NGSKOM M ISSION SPECIAL METAMERISM INDEX: CHANGE IN OBSERVER Pub. No CIE 80 1 st Edition 1989 UDC: 159.937 Descriptors:
2、Perception of colours 535.66 Colours of objects 61 2.843.31 Colour vision Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without
3、 license from IHS -,-,- - _- CIE 80 89 9006345 0003785 794 II This Technical Report has been prepared by CIE Technical Committee 1-07 o f Division 1 Vision es ist zur Verwendung durch CIE-Mitglieder und durch andere Interessierte bestimmt. Es sollte jedoch beachtet werden, da das Dokument eine Empfe
4、hlung und keine Vorschrift i s t . Die neuesten CIE- Tagungsberichte oder das neueste CIE-Journal sollten im Hinblick auf mgliche sptere Anderungen zu Rate gezogen werden. Any mention o f organisations or products does not imply endorsement by the CIE. Whilst every care has been taken in the compila
5、tion o f any lists, up to the time o f going to press, these may not be comprehensive. Toute mention dorganisme ou de produit nimplique pas une prfrence de la CIE. Malgr le soin apport la compilation de tous les documents jusqu la mise sous presse, ce travail ne saurait tre exhaustif. Die Erwhnung v
6、on Organisationen oder Erzeugnissen bedeutet keine Billigung durch die CIE. Obgleich groe Sorgfalt bei der Erstellung von Verzeichnissen bis zum Zeitpunkt der Drucklegung angewendet wurde, ist es mglich, da diese nicht vollstndig sind. Q CIE1989 Copyright International Commission on Illumination Pro
7、vided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without license from IHS -,-,- CIE BO 89 I 7006345 0003786 620 m III Foreword The following members of T. C. 1-07 (Observer Metamerism)
8、 took part in the prepa- ration of this Technical Report. The Committee comes under CIE Division 1 (Vision and Color). Member E. Allen H. Hemmendi nger K. McLaren Y. Nayatani N. Ohta (Chairman) J. J. Opstelten D. Strocka K. Takahama Consul tant R. W. G. Hunt P. K. Kaiser C. Wys zech i U. S. A. U . S
9、. A. Great Britain Japan Japan The Netherlands Germany, Federal Republic Japan Great Britain Canada Canada Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproductio
10、n or networking permitted without license from IHS -,-,- CIE 80 89 m 9006345 0003787 5b7 m IV Table of Contents Preface 1 . Introduction 2. Procedure 2.1 Average Color Differences and Metamerism Index M . b r 2.2 Range of Color Mismatches (1) Object Colors (2) Illuminant Colors 2.3 Age Effect of Col
11、or Mismatches Append ix References Table Page 1 8 9 13 14 Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without license from IH
12、S -,-,- Special Metamerism Index: Change in Observer Summary This report provides a method for evaluating the degree of color mismatch for a metameric color pair (object color or illuminant color) when an actual observer with normal color vision is substituted for the standard colorimetric observer.
13、 The method evaluates both the average values of, the color mi smatch. and the range of, Indice Special de Metamerisme: Changement de lobservateur Rsum Ce rapport fournit une mthode pour valurr 1 cart de couleur dune paire de coul eurs mtamres (coul eur d un ob jet ou d un i 1 1 urni nant 1 , 1 orsq
14、u un obser- vateur rel, ayant une vision normale des couleurs, est substitu lobserva- teur de rfrence colorimtrique. La mthode permet dvaluer, la valeur moyenne de lcart de cou- leur et ltendue de celui-ci. la fois, Spezieller Metamerie Index: Unterschiede im Beobachter Zusammenfassung Dieser Berich
15、t behandelt ein Verfahren zur Bestimmung des Maes der Farb- fehl abstimmung bei einem bedingt-gleichen Farbenpaar (Krperfarbe oder Farbe einer Lichtquelle) , wenn ein tatschlicher Beobachter m i t normalem Farbseh- vermgen statt des farbrnetechnischen Normalbeobachters eingesetzt wird. Mit dem besch
16、riebenen Verfahren lt sich sowohl der Durchschnittswert als auch der Gesamtumfang der Farbanpassung bestimmen. Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reprodu
17、ction or networking permitted without license from IHS -,-,- CIE 80 89 I 9006345 0003789 33T I 1 Preface Two specimens having identical tristimulus values, for a given illuminant and reference observer, are metameric if their spectral radiance factors differ from each other within the visible spectr
18、al range. This metameric color match is broken down either b y a change of the reference illuminant or the observer. The degree of color mismatch caused b y substituting a test illurninant of differ- ent relative spectral composi tion for the reference illuminant is classified as the Special Metamer
19、ism Index : Change in Illuminant (illuminant metamerism). . The method of evaluating illuminant metamerism has already .been formulated: the purpose of this report is to formulate a method of evaluating the degree of color mismatch for metameric color pairs (object colors or illuminant colors) cause
20、d by substituting a test observer with normal color vision for the reference observer (CIE Standard Colorimetric Observer). This is classified as the Special Metam- erism Index : Change in Observer (observer metamerism). Color mismatch caused by observer metamerism is inevitable for real observers w
21、ith normal color vision. The evaluation of observer metamerism thus gives a sound basis for establishing color difference tolerances for color matching using various metameric color pairs. It also gives an indication of the degree of i 1 luminant metamerism which can be considered al lowable in our
22、everyday 1 ives. The methods of evaluating observer metamerism are generally grouped into two categories. For a given set of metamers, they are : (1) using actual observers with normal color vision to calculate the average of, and the range of, the color mismatches between metamers : (2) selecting a
23、 set of color matching functions representing the individual variations among color normal observers, and using them to calculate the average of, and the range of, the color mismatches. Method 1 is straightforward, and work using this procedure has already been reported using the Davidson-Hemmending
24、er(D-H) color rule. l . - However, for actual metameric color pairs other than the D-H color rule, method 1 requires subjective evaluation of color mismatches which is difficult and unstable. Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employ
25、ees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without license from IHS -,-,- CIE 80 89 I 900bL45 0003790 051 2 Method 2 is therefore preferred. Once the suitable color matching functions are formulated, the calculation of color mismatc
26、hes is as simple as the calculation of tristimulus values. In the early stages of formulating method 2, the use of 20 sets of color matching functions for normal color vision was recommended. . 5 - 6 However, i t is rather cumbersome to use 20 sets of coIor matching functions in evaluating observer
27、me- tamerism and efforts were made to reduce the number to only one and propose a Standard Deviate Observer “ who has color matching functions which differ from those of the standard observer by amounts equal t o the standard deviations among the 20 sets of color matching functions. : these will be
28、referred to as the 20 observers hereafter. The method employed was a statistical analysis of the var- iances and covariances of the color matching functions of the 20 observers. However. i t was found that the Standard Deviate Observer did not give a satis- factory prediction of observer metamerism.
29、 An aiternative suggestion selected the best combination of two observers from among the 20 observers. I. These two observers give highly correlated results with those obtained by the 20 observers. A further proposal was to use a single Standard Deviate Observer by analyzing the same 20 observers bu
30、t by use of a different statistical method known as a singular value decomposi t ion. This Standard Deviate Observer gives a good prediction of the average value of color differences among the 20 observers. A method of evaluating the range of color mismatches was also proposed. . l a attempt to conf
31、irm these results a different approach using a nonlinear opti- mization of the 20 observers and actual metameric samples was performed. . I The results turned out to be much the same and the Standard Deviate Observer obtained well represented the original 20 observers. In an I t was later shown that
32、 the age distribution of the 20 observers was rather wide. ranging from about 20 to 60 years old and that apparent differences between the results obtained b y method and 2 are simply because of the difference in scaling of color differences. I The same analysis has been carried out for the color ma
33、tching functions of 53 Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without license from IHS -,-,- CIE 80 89 E 900bL45 0003793
34、 T 8 = 3 observers measured by Stiles et al. showing that the correlation between the ob- server metamerism indices by the 20 and by the 53 observers was satisfactory. However, the age distribution of the 53 observers is not uniform but significantly high in the twenties, and the contribution factor
35、s of the decomposed components from the 53 observers were lower than those derived from the 20 observers. For these reasons. the color match basis of the Present method. The research work reported dea imetric Observer. I t has also ng functions of the 20 observers are used for the s with the CIE 196
36、4 Supplementary Standard Color- been shown that observer variations in color matching functions are mainly caused b y the variation of eye-lens pigmentation due to the change of observer age. I . Therefore, the present method is also applicable for the CIE 1931 Standard Colorimetric Observer. 1. Int
37、roduction A method of evaluating the average of, and the range of, color mismatches for metameric color pairs when test observers are substituted for a reference observ- er is presented. The reference observer is either the CIE 1931 Standard Color- imetric Observer or the CIE 1964 Supplementary Stan
38、dard Colorimetric Observer. The test observers are assumed to be a number of actual observers with normal color vision, and are represented by four deviation functions characterizing the variations of color matching functions of color normal observers. When metameric colors are evaluated by the test
39、 observers, the resultant tristimulus values do not match each other. Instead they spread within a certain range in a three-dimensional color space. The range is characterized in a chromaticity diagram by a statistical confidence ellipse containing 95% of the spread. The following procedure gives an
40、 average color difference and the shape of the ellipse. The two-dimensional ell ipse does not contain information about the Psychometric lightness. The ellipse is therefore not applicable to the intercornparison of the degree of observer aietamerlsrn between two different metameric pairs. Rather i t
41、 shows the chromaticity gamut in color matches of color normal observers for a me- tameric sample pair, and also evaluates the adequacy of the observer variations Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, le
42、ee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without license from IHS -,-,- CIE AO 89 900bL45 0003792 924 4 of chromaticities in the color matches using a visual colorimeter for a number of color normal observers. Four sets of deviation functions A F i A ), AYi(A
43、), A T i ( A ) , i = 1,2,3, and 4. are used in the method. These functions are defined and tabulated from 380nm t o 780nm in 5nm steps. The first set of deviation functions in TabIe.l is the dif- ferences in color matching functions between the CIE Standard Colorimetric Ob- servers and the Standard
44、Deviate Observer, and is used to evaluate the average value of color differences, or the metamerism index. The additional three sets of deviation functions are. together with the first one, used to define the shape of el 1 ipse. In the following procedure, the subscript shows the kind of deviation f
45、unctions and the superscript the number of colors unless otherwise specified. This procedure is applied both for the CIE 1931 Standard Colorimetric Observer and for the CIE 1964 Supplementary Standard Colorimetric Observer. Though the metamerism index is Sig- nificant only for object colors. the var
46、iation of chromaticity coordinates, the confidence ellipse, is calculated both for object colors and for illuminant colors. 2. Procedure For a pair of object colors which is metameric with respect to a reference observer and an irradiating illuminant, their tristimulus values X r c t . Y r e t . 2 ,
47、 e f . j=l J J J and 2, are derived by the usual CIE recommendationl- I as ( j = 1,2 (2. 1) where LI ( 2 ) is the spectral reflectance of the j-th object color of the metameric pair, S ( A ) is the spectral power distribution of the illuminant irradiating the objects, and Y(A .Y(A ),T( A ) are the c
48、olor matching functions of either the CIE 1931 Standard Colorimetric Observer or the CIE 1964 Supplementary Standard Colorimetric Observer. The distribution S(A 1 is normalized as C S ( L ) Y ( A ) AR=100. A (2. 2) Copyright International Commission on Illumination Provided by IHS under license with CIELicensee=IHS Employees/1111111001, User=leee, leee Not for Resale, 11/24/2007 08:45:37 MSTNo reproduction or networking permitted without