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1、Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONWlEYHAPOHAR OPTAHMSAMR fl0 CTAHAPTM3AMWORGANISATION INTERNATIONALE DE NORMALISATION Photography - Camera lenses - Determination of ISO colour contribution index (lSO/CCI) Photographie - Objectifs pho tographiques - D is the Source; spectral powe
2、r distribution of the light t(A) is the axial relative spectral transmittance Camera lens (or Optical System); of the 4.3 Weighted spectral sensitivity values s(A) spectral sensitivity of the Camera film or Paper; 4.3.1 Illuminants A is the wavelength; 2, to A2 is the wavelength region over which gr
3、aphic film or Paper is sensitive. the photo- 4.3.1 .l Photographit daylight Most Camera colour films are designed to produce Optimum results with “photographic daylight” illumination. The spectral power distribution of daylight varies with the time of day, geographical location, and the orientation
4、of the illuminated surface. Extensive radiometric measurements were made for five different conditions of daylight normally encountered. Data corresponding to a correlated colour temperature of 5 500 K were selected as the most appropriate for photography and designated as D,. This is the prevailing
5、 condition when the sun is 40 above the horizon in a cloudless atmosphere (sec ISO 2239). The relative power distribution values for Dss are given in table 1 and used as a reference in this International Standard. 3.2 spectral sensitivity (of a film) : The reciprocal of the amount of radiant energy
6、required at each wavelength to pro- duce a specified density in the final image. 3.3 weighted spectral sensitivity values : Values ob- tained by combining the relative film sensitivity and relative spectral power values for daylight to simplify the determination of colour contribution index values.
7、3.4 colour contribution index (CCI) : A three number System which describes the degree to which a lens is expected to Change the Overall colour of a Photograph. relative to that obtained with no lens in the System. 4.3.1.2 Artifical illuminants Blue flashbulbs and electronie flash units are normally
8、 designed to produce the same photographic results as daylight even though their relative power distribution may be different. 4 Method of test 4.3.2 Spectral sensitivity of colour film 4.1 Principle Some layers of colour film are primarily sensitive to blue light, while others will have primary sen
9、sitivity in the green and red regions. Since colour films differ in their relative spectral sen- sitivity, the effective colour of a lens depends on the film used for evaluation. During 1977, manufacturers worldwide were requested to supply average spectral sensitivity data for their daylight-type C
10、amera colour films used in pictorial photo- graphy. Data from four manufacturers were received and averaged. The average values are used as references in this International Standard. Average spectral sensitivity values, The colour contribution index of a Camera lens is calculated from its spectral t
11、ransmittance values and the weighted spec- tral sensitivity values provided i n this International Standard. 42 . Lens transmittance values The spectral transmittance of a camera s imaging System, in- cluding such elements as lenses , mirrors and filters, has to be 2 Copyright International Organiza
12、tion for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 67284983 (El Table 1 - Spectral data Relative spectral Wavelength transmitt
13、ance Relative spectral power of the ISO Standard lens distribution of daylightl) (4 nm z (Al D55 350 om 28 360 0,07 31 370 0,23 34 380 0,42 33 390 0,60 38 400 0,74 61 410 OB 69 420 OB 72 430 0,Ql 68 440 0,94 86 450 0,95 98 460 0,97 100 470 0,98 100 480 0,98 103 490 0,QQ 98 500 0,QQ 101 510 WO 101 52
14、0 1, 100 530 1, 104 540 1m 102 550 lt) 103 560 1,oo * 100 570 WO 97 580 l,oo 98 590 0,QQ 91 600 0,QQ 94 610 0,QQ 95 620 0,98 94 630 0,98 90 640 0,97 92 650 0,97 89 660 0,96 90 670 0,95 94 680 0,94 90 690 0,94 80 1 CIE Publication No. 15 (E-1.3.1). Copyright International Organization for Standardiza
15、tion Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO6728=1983(E) S(A), for the blue, green and red sensitive layers, each normal- ized to a peak of
16、100, are given in table 2. Table 2 - Average relative colour-film sensitivity F(A) (The sensitivity of each layer is normalized to a peak of 100.) Wavelength Blue Green Red (4 nm I qiB (Al -qG (Al qj (Al 4.3.3 value Determination of weighted spectral sensitivity The spectral characteristics of a len
17、s tan be evaluated in terms of its total effect on the various layers of an average colour film. The effect on the blue sensitive layers is referred to as the blue photographic response to the lens. The relative blue photo- graphic response of the average colour film to D, illumination with no Camer
18、a lens in the System, tan be denoted as : s I2 Blue photographic response : RB = 0% S, (il) dA 4 . . . (2) where 055 is the relative spectral power distribution for D,; A, to 22 Multiply the integrand by a CO response equal to 100, i.e.; is the relative spectral sensitivity of the blue sen- sitive l
19、ayers 0 f average daylight-type colour film; is the wavelength layers are sensitive. over the blue KB to make the blue s A2 R, = KB D&.&) d! = 100 . . l (3) 1, equation (3) may be written : s A2 R, = JQ (Al dA. . . . (4) 4 where PVB (il) = Ks Ds F,m,m (il) The values of FV&) are called weighted spec
20、tral sensitivity values of the blue sensitive layers. Likewise, weighted values for the green WC (4 and red WR (AI sensitive layers tan also be calculated by equating their photographic responses to daylight to 100. In other words, the weighting factors have been derived so that the red, green, and
21、blue responses are equal when no lens is in the System. The values for We, W& and WR, are given in table 3. 44 . Photographit response using a lens The photographic blue response of average colour film using D, when a lens is included in the System, tan be determined from the general equation : s 12
22、 R, = w,(A) z(n) dA . . . (5) 4 where z (2) is the relative spectral transmittance of the lens. For discrete values of Wr (2) and z(A) f the blue response becomes : R, = C FV&, 7(A) . . . (6) Likewise, RG and R, are determined. NOTE - If a lens is to be used with a specific film or group of films, t
23、he spectral sensitivities of those products tan, of course, be used to determine the photographic response of a lens in that application. Since Camera lenses vary primarily in transmittance of shorter wavelengths, differentes in the spectral sensitivity of film in this region are generally the most
24、important in evaluating the effect of various lenses on the colour of the resultant Photograph. 4.5 Calculation of ISO colour contribution index (lso/cclI The relative spectral transmittance values of a lens are multi- plied by the weighted spectral sensitivity values for the blue, green, and red se
25、nsitive layers in table 3. The total photographic responses, RB, RG, and RR are obtained by sum- mation. Logt0 response values are determined to two decimal places. To simplify, make the smallest element of this three- number designation equal to zero by subtracting it from all three log values. 4 C
26、opyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6728-1983 (EI Table 3 - Weighted spectral se
27、nsitivity values W(A) evaluated. These calculations are illustrated in the example (to be used with transmittance values) below : di w,iA) 1, W,(A) 1 W&) 370 I 1 I- 380 1 390 3 400 7 410 10 420 12 430 12 440 13 450 13 460 12 470 8 480 4 490 2 500 510 520 530 540 550 25 560 13 570 13 580 9 590 2 1 1
28、2 4 5 8 15 600 1 610 / 6 620 8 630 640 650 22 660 16 670 4 680 1 12 19 A further simplification occurs if the decimal is eliminated by The ISO colour contribution index of a Camera lens determined multiplying by 100. The final reduction of the three-numbers is using the method specified in this Inte
29、rnational Standard may called the “Colour Contribution Index” for the particular lens be denoted in the form “ISOKCI 0/5/4”. R = 89 log10 RB = 1 g5 subtracting O O” multiplying o RG = “ l“glORG = 2tm each value R, = 97 loglo RR = 199 es 004 gives 4 Colour Contribution Index = 0/5/4 This means the av
30、erage colour film in D, illumination sees the lens as providing more green (by 0 05 log R) and red layer (by 0 04 log R) response relative to the blue than that obtained with no lens in the System. In other words, the lens would produce pictures which were primarily yellow when compared to those obt
31、ained with no lens present. An example showing all the calculations is given in annex A. 5 Tolerantes for CCI When the weighted factors in table 3 are used with the transmittance values of the ISO Standard Camera lens, the colour contribution index is 0/5/4 (sec annex A for calcula- tions). Film man
32、ufacturers generally establish aims for daylight-type colour products based on the D, illuminant and a Camera lens having the spectral transmittance values given in table 1. If a lens has characteristics significantly different from the ISO Standard Camera lens, the average picture produced from it
33、would be expected to be biased for colour balance. Such a lens would also produce colour shifts if it were used interchangeably with lenses which are close to the Standard lens for spectral transmittance. For this reason, it is recommended 0/5/4 be used as an aim for the colour contribution index of
34、 Camera lenses (or Optical imaging System). Suggested tolerantes for CCI are given in annex B. 6 Marking and labelling Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MD
35、TNo reproduction or networking permitted without license from IHS -,-,- ISO 67264983 (El Annex A Example of the method used for calculating the colour contribution index of a lens from transmittance measurements (Relative spectral transmittance values of the ISO Standard Camera lens are used in this
36、 example) (This annex does not form part of the Standard.) Wavelength Relative transmittance (Al nm 7 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction
37、or networking permitted without license from IHS -,-,- ISO 6728-1983 (E) Annex B Recommended values for colour contribution index of Camera lenses (This annex does not form part of the Standard.) The colour contribution index for an average ISO Standard Camera lens is 0/5/4. Ideally, all manufacture
38、rs should use this as an aim Point. As a guide, the following tolerantes, for each value, are recommended : Blue : 0 +3 -4 Green : 5 0 -2 Red : 4 +1 -2 A trilinear graph is a useful method for portraying CCI values. Plotting the above tolerantes yields a hexagon within which CCI values of lenses sho
39、uld fall (dotted lines in the figure). Index values should be plotted moving in the blue, green, and red directions indicated in the figure (for example, for CCI 0/2/3, starting at the origin O/O/O, move 0 unit in the blue direction, then 2 units in the green direc- tion, and from there, 3 units in
40、the red direction). Because the procedure for deriving CCI equates the smallest value to 0, it is not readily apparent whether a CCI is acceptable by com- paring the values directly to the above tolerantes. For example, in the case of 0/2/3, the green and red values do not seem to comply when compar
41、ed directly to the tolerantes. However, the plotted values indicate it falls within the hexagon. This is because indexes 0/2/3 and - 2/0/1 (all values meet the tolerantes) are equivalent and plot in the same location since they only differ because of a neutral shift ( - 2/ - 2/ - 2). Therefore, it i
42、s recommended that CCI indexes be plotted on a trilinear graph to determine if theycomply with the tolerantes. ns / /“ Tolerantes / _ _ / Gr!en / Yellow (- BI, / / -Cyan (-R) 4-a Figure - Trilinear graph 7 Copyright International Organization for Standardization Provided by IHS under license with IS
43、O Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally leff blank Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=N
44、ASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally left blank Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technica
45、l Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally left blank Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:55:36 MDTNo reproduction or networking permitted without license from IHS -,-,-