1、BRITISH STANDARD BS ISO 6846:1992 Implementation of ISO6846:1992 Photography Black-and-white continuous-tone papers Determination of ISO speed and ISO range for printing UDC 771.531.2:771.534:620.1BSISO6846:1992 This BritishStandard, having been prepared under the directionof the Consumer Products a
2、nd Services Sector Board, was published under the authority of the Standards Boardand comes into effect on 15December1995 BSI02-2000 The following BSI references relate to the work on this standard: Committee reference CPW/42 Draft for comment91/40027 DC ISBN 0 580 25112 8 Committees responsible for
3、 this BritishStandard The preparation of this BritishStandard was entrusted to Technical Committee CPW/42, Photography International coordination, upon which the following bodies were represented: British Film Institute British Institute of Professional Photography British Photographic Association S
4、ira 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 British Association of Oral and Maxillo-Facial Surgeons British Dental Association British Kinematograph, Sound and Televi
5、sion Society British Printing Industries Federation College of Radiographers Institute of Physics Institute of Practitioners in Advertising Lighting Industry Federation Ltd. Ministry of Defence Oil and Colour Chemists Association PICON Periodical Publishers Association Ltd. Photogrammetric Society P
6、ira International Royal Photographic Society Amendments issued since publication Amd. No. Date CommentsBSISO6846:1992 BSI 02-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO6846 1BSISO6846:1992 ii BSI 02-2000 National foreword This BritishS
7、tandard reproduces verbatim ISO6846:1992 and implements it as the UK national standard. This BritishStandard is published under the direction of the Consumer Products and Services Sector Board whose Technical Committee CPW/42 has the responsibility to: aid enquirers to understand the text; present t
8、o 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 well as overseas standards, are avai
9、lable from Customer Services, BSI,389 Chiswick High Road, London W44AL. 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 British Standard does not of itself confer im
10、munity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theISO title page, pagesii toiv, pages1 to8 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicat
11、ed in the amendment table on the inside front cover.ISO6846:1992(E) ii BSI 02-2000 Contents Page Foreword iii Introduction 1 1 Scope 2 2 Normative references 2 3 Definitions 2 4 Sampling and storage 2 5 Test method 2 5.1 Principle 2 5.2 Safelights 3 5.3 Exposure 3 5.3.1 Sample condition 3 5.3.2 Type
12、 of sensitometer 3 5.3.3 Radiant energy quality 3 5.3.4 Modulation 3 5.3.5 Exposure time 3 5.4 Processing 3 5.4.1 Conditioning of samples 3 5.4.2 Processing specifications 3 5.5 Densitometry 3 5.6 Evaluation 3 5.6.1 Sensitometric curve 3 5.6.2 Minimum density, D min 4 5.6.3 Maximum density, D max 4
13、5.6.4 Maximum net density, D N 4 6 Product classification 4 6.1 Speed calculation 4 6.1.1 ISO speed 4 6.1.2 ISO speed of a product 5 6.1.3 Accuracy 5 6.2 Range calculation 5 6.2.1 ISO range 5 6.2.2 ISO range of a product 5 6.2.3 Accuracy 5 7 Product marking and labelling 5 7.1 ISO speed 5 7.2 ISO ra
14、nge 6 7.3 General 6 Annex A (informative) Relationship between the paper range, R,andtheeffectivedensity range of the negative 7 Annex B (informative) Relationship between log exposure range and contrast 7 Annex C (informative) Relationship between log exposurerangeandaveragegradient 8 Annex D (info
15、rmative) Bibliography 8 Figure 1 Sensitometric curve 4 Table 1 ISO speed 5 Table 2 ISO range 6 Descriptors: Photography, black-and-white photography, photographic paper, classification, tests, determination, speed, exposure, modulation, marking, labelling.ISO6846:1992(E) BSI 02-2000 iii Foreword ISO
16、 (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 technical com
17、mittee 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 matters of electrot
18、echnical 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 least75% of the member bodies casting a vote. International Standard ISO6846 was prepared by Te
19、chnical Committee ISO/TC42, Photography. This second edition cancels and replaces the first edition (ISO6846:1983), of which it constitutes a technical revision. Annex A, Annex B, Annex C and Annex D of this International Standard are for information only.iv blankISO6846:1992(E) BSI 02-2000 1 Introd
20、uction This International Standard establishes a method for measuring 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
21、for this purpose. Studies have shown that highly acceptable prints 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
22、papers. Some diversion from this criterion can be required to obtain optimum prints because of subject matter, individual preferences, and paper characteristics such as D max , surface and curve shape. Each manufacturer has established a unique system for grading of papers and designations which mak
23、es it extremely difficult for users to identify products which are comparable 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
24、 variable contrast paper) for a given effective negative density range, 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
25、in density between the two points (density range); b) the slope of a 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 g
26、rades (see Annex B and Annex C). The diffuse density range of a negative 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 co
27、ntact printing, the term “effective density range” has been introduced (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 dens
28、ity range of a negative image can be calculated from the measured ISO 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
29、 A). Most manufacturers have classified photographic papers by using a grade number ranging from00to6. 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 reco
30、gnizing that users generally evaluate the density range of a negative (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 meth
31、od of classifying papers in this manner will have significant long-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
32、 by following the procedures herein are possibly not directly applicable when products are exposed using sources other than a tungsten lamp operating at2856K. Since a particular paper is designed to provide optimum results in particular processes, this International Standard does not specify one sin
33、gle process. To do so would be considered unduly restrictive and 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
34、and further Analysis of Results. Journal of the Optical Society of America,38 (11):1948.ISO6846:1992(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 papers used to make positive reflection prints of
35、 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 processed in conventional chemicals and equipmen
36、t, 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-pictorial applications; c) silver papers used to
37、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 indicated were valid. Allstandards are subject to revisi
38、on, 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 International Standards. ISO5-3:1984, Photography Densi
39、ty measurements Part3: Spectral conditions. ISO5-4:1983, Photography Density measurements Part4: Geometric conditions for reflection density. ISO554:1976, Standard atmospheres for conditioning and/or testing Specifications. ISO6728:1983, Photography Camera lenses Determination of ISO colour contribu
40、tion index (ISO/CCI). ISO/CIE10526:1991, CIE standard colorimetric illuminants. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 exposure 2) , H the time integral of illuminance on the paper measured in lux seconds and designated by the symbol H. Ex
41、posure 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 range, LER the range of log exposure values normally use
42、d 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, D min the minimum density value obtainable from an unexposed sample of the product following the process used in the ISO speed determination 4 Samplin
43、g 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 recommendations for a length of time to simulate the average
44、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 Handbook3 be used. Other suitable reference sources are given in the bibliography. 5 Test method 5.1 Princ
45、iple 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) CIE17.4 uses the term “luminous exposure”.ISO6846:1992(E)
46、BSI 02-2000 3 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 of23 C 2 C
47、 and a relative humidity of(50 5)% in accordance with ISO554. 5.3.2 Type of sensitometer The sensitometer shall be a non-intermittent, illuminance-scale type. 5.3.3 Radiant energy quality The spectral power distribution of the illuminant shall be that of a black body radiator operated at a temperatu
48、re of2856K (CIE standard illuminant A as described in ISO/CIE10526) modified by the ISOstandard camera lens as described in ISO6728. If this International Standard is followed in all respects except that the light from the source is modified by a filter, as in the case of variable contrast papers, t
49、his International Standard may be complied with by indicating that the speed and range quoted apply to the specific combination of paper and filter used. 5.3.4 Modulation The total range of spectral diffuse transmission density with respect to the paper plane of each area of the light modulation throughout the wavelength interval from400nm to700nm shall not exceed5% of the average density, or0,03density units, whichever is greater. In the interval from360nm to400nm,10% of this same average density or0,06density units, whichever is greater, is acce
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