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1、BRITISH STANDARD BS ISO 6846:1992 Implementation of ISO 6846:1992 Photography Black-and-white continuous-tone papers Determination of ISO speed and ISO range for printing UDC 771.531.2:771.534:620.1 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c
2、) BSI BS ISO 6846:1992 This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1995 BSI 02-2000 The following BSI references relate to the work on
3、 this standard: Committee reference CPW/42 Draft for comment 91/40027 DC ISBN 0 580 25112 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee CPW/42, Photography International coordination, upon which the following bodies w
4、ere represented: British Film Institute British Institute of Professional Photography British Photographic Association Sira Limited The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Association of Teachers of Printing and Allied Subjects Br
5、itish Association of Oral and Maxillo-Facial Surgeons British Dental Association British Kinematograph, Sound and Television Society British Printing Industries Federation College of Radiographers Institute of Physics Institute of Practitioners in Advertising Lighting Industry Federation Ltd. Minist
6、ry of Defence Oil and Colour Chemists Association PICON Periodical Publishers Association Ltd. Photogrammetric Society Pira International Royal Photographic Society Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006
7、, Uncontrolled Copy, (c) BSI BS ISO 6846:1992 BSI 02-2000i Contents Page Committees responsibleInside front cover National forewordii Forewordiii Text of ISO 68461 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 6846:1992 ii BSI 02-20
8、00 National foreword This British Standard reproduces verbatim ISO 6846:1992 and implements it as the UK national standard. This British Standard is published under the direction of the Consumer Products and Services Sector Board whose Technical Committee CPW/42 has the responsibility to: aid enquir
9、ers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standards, as
10、 well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London W4 4AL. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Britis
11、h Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the ISO title page, pages ii to iv, pages 1 to 8 and a back cover. This standard has been updated (see copyright date) and may have had
12、 amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled C
13、opy, (c) BSI ISO 6846:1992(E) ii BSI 02-2000 Contents Page Forewordiii Introduction1 1Scope2 2Normative references2 3Definitions2 4Sampling and storage2 5Test method2 5.1Principle2 5.2Safelights3 5.3Exposure3 5.3.1 Sample condition3 5.3.2 Type of sensitometer3 5.3.3 Radiant energy quality3 5.3.4 Mod
14、ulation3 5.3.5 Exposure time3 5.4Processing3 5.4.1 Conditioning of samples3 5.4.2 Processing specifications3 5.5Densitometry3 5.6Evaluation3 5.6.1 Sensitometric curve3 5.6.2 Minimum density, Dmin4 5.6.3 Maximum density, Dmax4 5.6.4 Maximum net density, DN4 6Product classification4 6.1Speed calculati
15、on4 6.1.1 ISO speed4 6.1.2 ISO speed of a product5 6.1.3 Accuracy5 6.2Range calculation5 6.2.1 ISO range5 6.2.2 ISO range of a product5 6.2.3 Accuracy5 7Product marking and labelling5 7.1ISO speed5 7.2ISO range6 7.3General6 Annex A (informative) Relationship between the paper range, R, and the effec
16、tive density range of the negative7 Annex B (informative) Relationship between log exposure range and contrast7 Annex C (informative) Relationship between log exposure range and average gradient8 Annex D (informative) Bibliography8 Figure 1 Sensitometric curve4 Table 1 ISO speed5 Table 2 ISO range6
17、Descriptors: Photography, black-and-white photography, photographic paper, classification, tests, determination, speed, exposure, modulation, marking, labelling. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6846:1992(E) BSI 02-2000iii
18、 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a
19、technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matter
20、s of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 6846 wa
21、s prepared by Technical Committee ISO/TC 42, Photography. This second edition cancels and replaces the first edition (ISO 6846:1983), of which it constitutes a technical revision. Annex A, Annex B, Annex C and Annex D of this International Standard are for information only. Licensed Copy: sheffieldu
22、n sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6846:1992(E) BSI 02-20001 Introduction This International Standard establishes a method for measur
23、ing those photographic characteristics of papers used for printing from negative images which will aid users to select the appropriate products for their applications. ISO speed and ISO range are two measurements considered important for this purpose. Studies have shown that highly acceptable prints
24、 are generally obtained if the log exposure range (LER) of a photographic paper is equal to the effective density range of the negative.1) Therefore, ISO range, which is directly related to LER provides a useful criterion for grading papers. Some diversion from this criterion can be required to obta
25、in optimum prints because of subject matter, individual preferences, and paper characteristics such as Dmax, surface and curve shape. Each manufacturer has established a unique system for grading of papers and designations which makes it extremely difficult for users to identify products which are c
26、omparable for printing characteristics. The ISO range number is introduced to reduce this source of confusion. ISO range is not a measure of image contrast, but a useful guide for selecting the proper paper (or the proper filter for variable contrast paper) for a given effective negative density ran
27、ge, and for comparing products from various manufacturers. Print image contrast can be specified by three different types of objective measurements in relation to two specified points on the paper characteristic curve a) difference in density between the two points (density range); b) the slope of a
28、 straight line connecting the points (average gradient); and c) the difference in log exposure for the two points (log exposure range). Of the three, log exposure range is most closely associated with the concept of paper contrast grades (see Annex B and Annex C). The diffuse density range of a nega
29、tive is not an accurate measure of the illuminance range at the printing plane when printers are employed that have specular type optical systems. Since conditions which satisfy the diffuse density criteria normally exist only in contact printing, the term “effective density range” has been introduc
30、ed (see Annex A). It is the effective density range of the negative which should be matched with the log exposure range of the printing material in the usual projection printing mode for optimum tone reproduction. The effective density range of a negative image can be calculated from the measured IS
31、O diffuse transmission density range by applying the proper correction factors for specularity and flare to the values. Alternatively, the illuminance range can be measured in the printing plane with a suitable photometer (see Annex A). Most manufacturers have classified photographic papers by using
32、 a grade number ranging from 00 to 6. The larger the grade number, the greater is the contrast within a specific line of papers. ISO range numbers will generally be lower as contrast increases. The concept of ISO range was adopted recognizing that users generally evaluate the density range of a nega
33、tive (visually) in selecting the paper grade to use. If the density range is small, a paper with a small ISO range number should be used. It will take time to adapt to this new concept, but establishing an internationally accepted method of classifying papers in this manner will have significant lon
34、g-term benefits for users. It is not feasible to include provisions in this International Standard for the wide range of exposing conditions used in the trade. For this reason, the interpretation of the speed and range numbers obtained by following the procedures herein are possibly not directly app
35、licable when products are exposed using sources other than a tungsten lamp operating at 2 856 K. Since a particular paper is designed to provide optimum results in particular processes, this International Standard does not specify one single process. To do so would be considered unduly restrictive a
36、nd could result in yielding ISO speed and ISO range numbers which were not typical of those obtained in processes specified by the manufacturer. 1) JONES, L.A. and NELSON, C.N. Control of Photographic Printing: Improvements in Technology and further Analysis of Results. Journal of the Optical Societ
37、y of America, 38 (11):1948. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6846:1992(E) 2 BSI 02-2000 1 Scope This International Standard specifies the method for determining the ISO speed and ISO range of black-and-white photographic p
38、apers used to make positive reflection prints of continuous-tone subjects from black-and-white film negatives. It pertains to all conventional silver-halide contact and enlarging papers used for continuous-tone or pictorial photography. This includes papers with variable contrast. The papers may be
39、processed in conventional chemicals and equipment, but also using special procedures such as those involving activators or heat for development. This International Standard does not apply to: a) non-silver papers; b) high contrast silver papers, such as those used in the graphic arts, or other non-p
40、ictorial applications; c) silver papers used to obtain a direct positive or reversal image. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicate
41、d were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid Intern
42、ational Standards. ISO 5-3:1984, Photography Density measurements Part 3: Spectral conditions. ISO 5-4:1983, Photography Density measurements Part 4: Geometric conditions for reflection density. ISO 554:1976, Standard atmospheres for conditioning and/or testing Specifications. ISO 6728:1983, Photogr
43、aphy Camera lenses Determination of ISO colour contribution index (ISO/CCI). ISO/CIE 10526:1991, CIE standard colorimetric illuminants. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 exposure2), H the time integral of illuminance on the paper meas
44、ured in lux seconds and designated by the symbol H. Exposure is often expressed in base ten logarithmic form 3.2 speed a quantitative measure of the response of the photographic material to radiant energy for the specified conditions of exposure, processing, and image measurement 3.3 log exposure ra
45、nge, LER the range of log exposure values normally used to produce a final print. It is the difference in log exposure values required to produce two specified densities on the paper 3.4 minimum density, Dmin the minimum density value obtainable from an unexposed sample of the product following the
46、process used in the ISO speed determination 4 Sampling and storage In determining the ISO speed and ISO range of a product, it is important that the samples evaluated yield the average results obtained by users. Prior to evaluation, the samples shall be stored according to the manufacturers recommen
47、dations for a length of time to simulate the average age at which the product is normally used. To assure that all components of variance are included in the sampling plan, it is recommended that procedures such as those outlined in ISO Standards Handbook 3 be used. Other suitable reference sources
48、are given in the bibliography. 5 Test method 5.1 Principle Samples are exposed and processed as specified below. Density measurements are obtained from the resultant image to produce a sensitometric curve from which measurements are taken and used to determine ISO speed and ISO range values. 2) CIE
49、17.4 uses the term “luminous exposure”. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 12:44:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6846:1992(E) BSI 02-20003 5.2 Safelights To eliminate the possibility of safelight illumination affecting the sensitometric results, all papers shall be handled in complete darkness until thoroughly fixed. 5.3 Exposure 5.3.1 Sample condition During exposure, the samples shall be held at a temperature of 23 C 2 C and a relative humidity of (50 5) % in accordance with ISO 554. 5.3.2 Type of