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1、 American National Standards Institute 11 West 42nd Street New York, New York 10036 ANSI/I3A IT2.39-1998 (R2004) for Photography Black-and-White, Continuous-Tone Films Photographic Modulation Transfer Function Copyright American National Standards Institute Provided by IHS under license with ANSI Li
2、censee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- Reaffirmation and redesignation ? of ANSI/PIMA IT2.39-1998 Copyright American National Standards Institute Provided by IHS under license w
3、ith ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- ANSI/PIMA IT2.39-1998 Revision and redesignation of ANSI PH2.39-1977 (R1990) American National Standard for Photography Black-a
4、nd-White, Continuous-Tone Films Photographic Modulation Transfer Function Secretariat Photographic their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conform
5、ing to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the n
6、ame of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the Ameri
7、can National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. American National Sta
8、ndard Published by American National Standards Institute, Inc. 11 West 42nd Street, New York, NY 10036 Copyright 1998 by American National Standards Institute All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior
9、 written permission of the publisher. Printed in the United States of America Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted w
10、ithout license from IHS -,-,- i Contents Page Forewordii 1 Scope . 1 2 Normative references. 1 3 Definitions. 1 4 Sampling and storage. 2 5 Test method 2 6 Test patterns. 2 7 Camera. 5 8 Camera and test pattern system calibration. 6 9 Exposure 7 10 Processing 8 11 Evaluation 8 Figures 1 Variable are
11、a test pattern. 3 2 Variable area calibration patch. 4 3 System calibration 6 4 Analysis of measurements . 10 5 Data presentation example. 11 Annexes A Test method considerations . 12 B Adjustment of test pattern modulation 13 C Suggested optics 14 D Microdensitometry considerations 15 E Interlabora
12、tory tests 16 F Bibliography 17 Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- ii Foreword (Thi
13、s foreword is not part of American National Standard ANSI/PIMA IT2.39-1998.) Modulation transfer curves have become an accepted means of describing certain characteristics relating to the sharpness of sensitized photographic materials. This standard describes a method for measuring the photographic
14、modulation transfer function of black-and-white, continuous-tone films that have an emulsion coated on one side of a transparent support. Color photographic materials have been specifi- cally excluded from the scope of this standard due to the complexity of specifying the input modulation of the act
15、inic exposure and the associated readout of the resulting images. When certain conditions are fulfilled, the modulation transfer curve for one compo- nent of a system can be cascaded with the modulation transfer curves representing other components of the system. Although such cascading is useful an
16、d desirable in systems that include photographic components, this standard does not claim that the modulation transfer function will necessarily give a representative system response when it is cascaded with other components of the system. Factors beyond the scope of this standard have to be include
17、d when precise predic- tions of the density of fine detail in photographic reproductions are to be derived by cascading the modulations transfer curves of system components. A method for pre- dicting the densities of fine detail in photographic images has been proposed by C. N. Nelson 3. 1) It is im
18、portant to note that the photographic modulation transfer function, as it is de- fined in this standard, is a measure of the apparent scattering of light within an un- processed emulsion: it is not a measure of the transmittance of the processed photographic image. The gradient of the density log ex
19、posure curve provides a very approximate factor relating the modulation associated with the light scattered within the unprocessed emulsion with the modulation associated with the light transmitted by the processed emulsion. A more exact relationship can be obtained by means of the more detailed pro
20、cedures given in Nelsons paper. This standard has been written in such a way as to allow the use of the basic camera system, except for optics, that meets the requirements of ANSI/PIMA IT2.38-1998, Photography Photographic materials Determination of ISO resolving power . This standard contains six a
21、nnexes that are informative and are not considered part of the standard. Suggestions for improvement of this standard will be welcome. They should be sent to the Photographic e-mail: . This standard was processed and approved for submittal to ANSI by PIMA Technical Committee on Image Evaluation, IT2
22、. Committee approval of the standard does not necessarily imply that all committee members voted for its approval. At the time this standard was approved, the IT2 Committee had the following members: Michael R. Goodwin, Chairman Jack Holm, Vice-Chairman James E. Harvey, Secretary _ 1) Numbers in bra
23、ckets correspond to references listed in annex F. Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,
24、- iii Organization RepresentedName of Representative Photographic Elis the minimum irradiance measured in the sinusoidal pattern. 3.2 photographic modulation transfer factor (PMTF): For a given spatial frequency, it is the ratio of the apparent modulation of the exposure pattern in the emulsion, as
25、measured by photographic radiometry using the emulsion as its own radiometer, to the actual modulation of the sinusoidal pattern incident on the emulsion surface (see annex A). Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Y
26、okosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- ANSI/PIMA IT2.39-1998 2 3.3 photographic modulation transfer function: The functional relationship between modulation transfer factors and spatial frequency when the modul
27、ation transfer factors are derived by the method de- scribed in this standard. 4 Sampling and storage 4.1 Product sampling In determining the photographic modulation transfer function of a product, it is important that the samples evaluated are representative of those used by the consumer. No fewer
28、than three samples shall be ob- tained from the plant of the manufacturer or from an accredited distributor if they cannot be obtained di- rectly from the manufacturer. In any case, the samples should be taken from products stored in accor- dance with the manufacturers recommendations and available
29、in the market. Each sample shall repre- sent a different batch of product. 4.2 Storage of samples After procurement from the manufacturer or distributor, all samples of a product shall be stored in the un- opened package for 2 to 4 months under conditions recommended by the manufacturer. When no spe
30、cific recommendation is made, storage shall be at 23 oC + 5oC and a relative humidity of 50% + 20%. At the end of this storage period, samples should be tested. The basic objective in selecting and storing samples as described above is to ensure the film characteristics obtained are representative o
31、f those obtained by a consumer at the time of use. 5 Test method Patterns with spatially varying sinusoidal irradiances and calibration areas are projected onto the film by a high-quality lens system. The processed exposures are subsequently evaluated with a suitable microden- sitometer. 6 Test patt
32、erns 6.1 Types of test patterns Sinusoidal test patterns may be either the variable area type or the variable transmittance type. In either case, the size of the images in the film plane shall be the same for all frequencies and shall be 2.0 mm + 0.5 mm in width and 1.6 mm + 0.4 mm in height. The ha
33、rmonic content of the sinusoidal test patterns at any frequency, as measured in the film plane, shall not exceed 10%. 6.1.1 Variable area test pattern The variable area test pattern requires the use of a cylindrical lens at the imaging lens to smear the pattern image into a variable irradiance distr
34、ibution in the film plane. A variable area test pattern, such as is shown in figure 1, may consist of the upper portion, where the vertical height of the opening is propor- tional to a sinusoidal function of the horizontal distance, and the lower portion which is of constant height and serves to red
35、uce the modulation of the sinusoidal portion of the test pattern. Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without licen
36、se from IHS -,-,- ANSI/PIMA IT2.39-1998 3 Figure 1 Variable area test pattern 6.1.2 Variable transmittance test pattern In this case, the transmittance of the pattern varies with distance in a sinusoidal manner between the maximum and minimum limits that define the modulation of the test pattern. Th
37、e maximum transmittance of any portion of the pattern shall not exceed 50%. 6.2 Aerial image modulation The modulation of the aerial image of the test pattern shall be 35% + 5%. The exact modulation of the aerial image shall be measured by the method described in 8.1. To produce this modulation leve
38、l, it will be necessary to have the modulation of the test patterns increase with increasing spatial frequency to com- pensate for the modulation transfer function characteristics of the camera lens. All test-pattern aerial images shall have the same average irradiance + 12% (see annex B). 6.3 Test
39、pattern frequencies The lowest spatial frequency in the film plane shall be 1.2 cycles/mm + 5%. The highest frequency shall be 200 cycles/mm + 5%. There shall be at least thirteen frequencies, and the increments between fre- quencies shall be no more than a factor of 1.6. A typical set of frequencie
40、s is 1.25, 1.6, 2.5, 4.0, 6.3, 10, 16, 25, 40, 63, 100, 160, and 200 cycles per mil- limeter. 6.4 Illumination of the test patterns The test patterns shall be transilluminated with a light source having a correlated color temperature of 3000 K + 250 K or 5500 K as specified in ANSI/ISO 7589, ANSI/NA
41、PM IT2.29. A color filter may be used with these illuminants. If used, the color filter should be stated with any results determined by this method. Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for R
42、esale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- ANSI/PIMA IT2.39-1998 4 6.4.1 Uniformity The irradiance across the test pattern area, as measured in the film plane, shall be uniform within + 4% over the central 1.2 mm x 1.2 mm area and within + 8%
43、 over the remaining area. A measurement method is described in clause 8. 6.4.2 Specularity Either diffuse or specular illumination of the test patterns may be used. In the case of the variable trans- mittance test patterns, the same type of illumination shall be used for the test pattern calibration
44、 to ensure that the evaluation of their harmonic content is valid. In the case of specular illumination of the test pat- terns, care shall be taken to ensure that the full aperture of the camera lens is filled with light from the test patterns. 6.5 Calibration patches 6.5.1 Variable area calibration
45、 patches In addition to the sinusoidal test patterns, the film shall be exposed to a series of calibration patches hav- ing known exposure increments. One such test object patch is shown in figure 2. There shall be at least eleven such patterns having log exposure increments no larger than 0.10 from
46、 patch to patch. The openings of these test objects shall range from at least twice the maximum total verti- cal opening of the lowest frequency sinusoidal pattern to one-half the minimum total vertical opening. One patch (the sixth, if there are eleven patches) should have an opening such that its
47、effective irradiance, as measured in the exposure plane by the radiometric technique outlined in clause 8, is equal to the average effective irradiance, measured in the film plan, of the lowest frequency sinusoidal test pattern. The cali- bration patch images in the film exposure plane shall be the
48、same size as the sinusoidal test pattern im- ages. Figure 2 Variable area calibration patch Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=USN Ship Repair Facility Yokosuka/9961031100 Not for Resale, 05/08/2007 22:38:18 MDTNo reproduction or networking permitted without license from IHS -,-,- ANSI/PIMA IT2.39-1998 5 6.5.2 Variable transmittance calibration patches The calibration patches for use with the variable transmitta