1、STD-SMPTE RP LBO-ENGL 1999 8357401 0003b12 451 U SMPTE RECOMMENDED PRACTICE RP 180-1999 Revision of RP 180-1994 Spectral Conditions Defining Printing Density in Motion-Picture Negative and Intermediate Films Introduction When a motion-picture color negative or intermediate film is printed, the dyes
2、in the negative or intermediate modulate the red, green, and blue exposures of the print material. The printing densities of the negative are a measure of this exposure modulation. Printing density is the density of the negative as “seen“ by the printer and print material. The IS0 has defined status
3、 M density for the evalu- ation of color photographic materials intended for printing. Status M density measurements are widely and satisfactorily used in process control in motion- picture, amateur color negative, and reversal printing originals. However, given the large number of films in use, sta
4、tus M densities can only approximate printing densities for most materials. A definition of printing density appropriate to the specific motion-picture negative and intermediate materials being used is needed for the calibration of film scanners and defini- tion of the metric used in computer data f
5、iles for electronic post-production of film. Motion-picture films are manufactured so as to repro- duce properly a gray scale with matched gammas in the final print, and the negatives and intermediate films are designed to present matched printing density gammas to the print materials. Thus, the pri
6、nting densities of a negative will correctly measure the relative gammas of the negative. Printing densities can be measured relative to a 100% transmitting reference, to the film Dmin, or to a reference gray step. In the latter case, an ideal film would have matched, superimposed red, green, and bl
7、ue gray scale printing densities. The printing exposures are determined by the product of the spectral power distribution of the printing light source, any spectral filtration in the printer, and the spectral sensitivities of the print material. Ideally, a Page 1 of 3 pages measure of printing densi
8、ty would exactly duplicate these properties. This is not possible in practice owing to the large variety of printers and materials that exist. The practical goal in specifying a printing density measure is to require that the printing density measurement correctly specifies the printing gammas of ty
9、pical motion-picture color negative and inter- mediate materials. 1 Scope This practice defines the spectral conditions defining the printing density gammas of motion-picture color negative and intermediate materials. It is not intended as a replacement for the status M density spectral conditions g
10、iven in ANSVIS0 5-3 and commonly used for the evaluation of color photographic materials used for printing. 2 Spectral conditions for printing density measurements The spectral conditions defining the printing densities of motion-picture negative and intermediate materials are tabulated in table 1.
11、These spectral responses, labeled R G and B respectively, are arbitrarily normalized to have unit response at the peak sensitivity. In actual use, the densitometer would be adjusted to cause zero density to correspond to a 100% transmitting material or to the Omin of the film being measured. This in
12、strument zero adjustment will have the effect of renormalizing the data of table 1. 3 Application The following equations define the relationship between printing density and printing exposure which is determined by measurements using the spectral responses of table 1 : Copyright O 1999 by the SOCIE
13、TY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved April 23, 1999 STDmSflPTE RP 380-ENGL 1997 M 8357403 O003633 378 E RP 180-1999 Table 1 - Spectral conditions for the measurement of motion-picture film printing density W.L. (nrn) R G
14、B 360 0.0000 0.0000 0.0000 370 0.0000 0.0000 0.0000 0.0052 380 0.0000 0.0000 1 I 390 0.0000 0.0000 0.0628 , 40 O 41 O 0.0000 0.0000 0.0000 0.0000 0.1692 0.41 41 420 430 440 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.7625 1 .o000 0.8754 450 460 470 480 490 500 0.0000 0.0000 0.0000 0.0000 0.0000 0.00
15、00 0.0000 0.0000 0.0005 0.0012 0.0049 0.0366 0.551 2 0.261 9 0.1075 0.0262 0.001 8 0.0000 51 O 520 530 0.0000 0.0000 0.0000 0.2714 0.71 52 1 .o000 0.0000 0.0000 0.0000 540 0.0000 0.8779 0.0000 550 0.0000 . 0.4584 0.0000 560 0.0000 0.1317 0.0000 570 0.0000 0.0079 0.0000 580 0.0000 0.0025 0.0000 590 0
16、0000 0.001 3 0.0000 600 0.0000 0.0000 0.0000 61 O 0.0010 0.0000 0.0000 620 0.0177 0.0000 0.0000 630 640 650 0.091 3 0.2223 0.491 7 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 660 0.8267 0.0000 0.0000 670 1 .o000 0.0000 0.0000 680 0.7937 0.0000 0.0000 690 0.4487 0.0000 0.0000 7nn n inn7 n nnnn n nnnn
17、I UV V. I JVI V.VVVV U.VVVV I 71 O 720 730 740 0.0752 0.0097 0.0000 0.0000 - 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Page 2 of 3 pages STD-SMPTE RP 180-ENGL 1999 D 8357403 0003bL4 224 RP 180-1 999 where R G and B refer to the spectral responses in table 1, TF is the film sample spect
18、ral transmittance, and TS is the spectral transmittance of the reference used to normalize the data or to adjust the zero of the measurement. The printing densities relate to the printing exposures as follows: PDR = LOGio (ER) PDG = LOGio (EG) PDB = LOG10 (EB) Printing densities computed using the a
19、bove rela- tionships can be used to calibrate film samples which in turn can be used to calibrate film scanners. Also, the computed printing densities can be used to derive a transformation matrix to transform status M density measurements to printing density. Finally, the spectral data listed in ta
20、ble 1 serves as an aim point for designing the spectral responses of film scanners and possibly densitometers. Annex A (informative) Bibliography ANSIAS0 5-3-1 995, Photography - Density Measurements - Part 3: Spectral Conditions Press Ltd.; 1975. P. 237. Hunt, R.W.G. The reproduction of colour. London: Fountain Evans, R.M.; Hanson, W.T., Jr.; and Brewer, W.L. Principles of color photography. New York: John Wiley 1953. Pp. 191 and 423. Page 3 of 3 pages
