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6、iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Requirements.3 4.1 General .3 4.2 Influx spectrum3 4.3 Types of instruments 5 4.4 Spectral products5 4.5 Computation of ISO 5 standard density from spectral data .6 4.6 Sample conditions.6 4.7 R
7、eference standards.6 5 Notation 7 6 Types of ISO 5 standard density7 6.1 ISO 5 standard visual density 7 6.2 ISO 5 standard printing density.7 6.3 ISO 5 standard status A density 8 6.4 ISO 5 standard status M density9 6.5 ISO 5 standard status T density.9 6.6 ISO 5 standard status E density 9 6.7 IS
8、O 5 standard narrow-band density.10 6.8 ISO 5 standard status I density10 6.9 ISO 5 standard type 3 density11 7 Spectral conformance, repeatability, stability and bias11 7.1 Spectral conformance.11 7.2 Repeatability, stability and bias.11 Annex A (normative) Reference tables of spectral products and
9、 weighting factors.25 Annex B (normative) Computation of ISO 5 standard density from spectral data 26 Annex C (informative) Method used to derive spectral weighting factors based on historical spectral product data28 Annex D (informative) Method used to derive abridged spectral weighting factors fro
10、m 1 nm reference spectral product data.29 Annex E (informative) Plots of relative spectral power distributions for influx spectra, and spectral products for ISO 5 standard density 33 Annex F (informative) Spectral conformance 40 Bibliography41 ISO 5-3:2009(E) iv ISO 2009 All rights reservedForeword
11、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 technical
12、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 matters of elect
13、rotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the
14、member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for ident
15、ifying any or all such patent rights. ISO 5-3 was prepared by ISO/TC 42, Photography, and ISO/TC 130, Graphic technology, in a Joint Working Group. This third edition cancels and replaces the second edition (ISO 5-3:1995), which has been technically revised. This technical revision takes into accoun
16、t, in particular, computation of ISO 5 standard density from spectral data, as well as graphic arts considerations. In the course of this technical revision, all parts of ISO 5 have been reviewed together, and the terminology, nomenclature and technical requirements have been made consistent across
17、all parts. ISO 5 consists of the following parts, under the general title Photography and graphic technology Density measurements: Part 1: Geometry and functional notation Part 2: Geometric conditions for transmittance density Part 3: Spectral conditions Part 4: Geometric conditions for reflection d
18、ensity ISO 5-3:2009(E) ISO 2009 All rights reserved vIntroduction 0.1 General The ISO 5 series comprises four International Standards that specify the spatial and spectral conditions for optical densitometry for use in black-and-white and colour imaging applications, as practised in photographic and
19、 graphic technology applications. The term “ISO 5 standard density” is used within the ISO 5 series to refer to such specified conditions. The more general term “density” is used in its traditional sense when the basic optical principles and concepts are being discussed. To define an ISO 5 standard
20、density value fully, it is necessary to specify both the geometric and spectral conditions of the measuring system. Geometric conditions are described in ISO 5-2 for transmittance ISO 5 standard density, and in ISO 5-4 for reflection ISO 5 standard density. This part of ISO 5 specifies the spectral
21、conditions for both transmittance and reflection ISO 5 standard density measurements. For many of these conditions, the term “status density” is used to identify them. 0.2 Density measurement In photography, optical density is a measure of the modulation of light or other radiant flux by a given are
22、a of the recording medium. The measurement of density can be of interest for various reasons. It might be necessary to assess the lightness or darkness of an image, to predict how a film or paper will perform in a printing operation, or to determine a measure of the amounts of colorants in the image
23、 for the purpose of controlling a colour process. If the visual effect is of interest, the spectral conditions of measurement need to simulate an appropriate illumination and the spectral sensitivity of the eye. For photographic printing operations, the spectral power distribution of the source to b
24、e used in the printing operation and the spectral sensitivity of the print material need to be simulated. In evaluating original material for colour separation, the illuminant, the spectral sensitivity of the separation medium, and the spectral transmittance of the tricolour separation filters (and
25、other optical components) need to be simulated. In order to provide measurement data that can be properly interpreted by the various users who need to do so, the provision of standard specifications for the measurement procedure is necessary. ISO 5 provides that specification. In this part of ISO 5,
26、 a number of spectral conditions are specified, including a definition of the spectral response for each. NOTE Spectral response is a function of the spectral sensitivity of the photodetector and the spectral modifications by any of the optics and filters between the plane of the specimen and the ph
27、otodetector. In many applications, it is considered desirable for the spectral response to match the spectral sensitivity of the intended receiver (eye, photographic paper, etc.) used in the practical applications of the product as described above. However, in other applications, the spectral respon
28、se is defined somewhat arbitrarily (though frequently with some regard to the spectral characteristics of the media being measured) to facilitate unambiguous communication for issues of process control and thus the spectral product also becomes arbitrary in those instances. The various spectral cond
29、itions specified in this part of ISO 5 have each been shown to be useful to the application identified. For example, certain types of density measurements are often made to generate sensitometric curves which are used to characterize the photographic properties of films and papers. Densities can als
30、o be used to perform a photographic tone-reproduction analysis or to monitor operations like photoprocessing. In graphic technology, reflection density measurements are used for the control of the ink film thickness, or, more generally, the amount of colorant per area and the determination of the to
31、ne values or other quantities. ISO 5-3:2009(E) vi ISO 2009 All rights reservedIn the early years of densitometry, the spectral responses of instruments were specified only in terms of the colour filters used in the construction. Although it was seldom the case, it was assumed that the spectral respo
32、nses of the detector and the source spectral energy distributions, as well as all intervening optical components, were the same in all instruments. In more recent times, densitometry standards have specified that the combination of all these components equals a given set of published “documentary” v
33、alues. If each of these components is approximated by a mathematical function, then their combination could be approximated by simply multiplying the spectral characteristics, wavelength by wavelength, and compiling the results into a table of numbers known as the spectral products. Such a specifica
34、tion allows flexibility to the manufacturer while providing for improved accuracy and precision. It also allows for reference materials to be manufactured and certified based on fundamental measurements. 0.3 Calculation of density In this revision of this part of ISO 5, it has been recognized that t
35、he use of simple filter instruments is in decline. The more common method of “measuring” ISO 5 standard density makes use of computations based on measurements of the spectral reflectance factor or spectral transmittance of the specimen under study. Many users have achieved this calculation in the p
36、ast by summing, over the full wavelength range, the product of the spectral reflectance factor or transmittance and the spectral products provided in previous editions of this international standard (defined at 10 nm intervals), after converting them to the linear domain. However, such a procedure i
37、s not strictly accurate. The spectral products are assumed to be the specification, at 10 nm intervals, of the physical spectral characteristics of a device obtained by combining spectral data pertaining to its illumination source and its optical components. Where measurements of samples made with a
38、 device conforming to this specification were compared to those computed from spectral data of the same samples, calculated by summing over the full wavelength range the product of the spectral data and the linear form of the 10 nm spectral products, small differences would be found. Although such e
39、rrors are likely to be very small with the typical samples encountered in photography and graphic technology (probably in the third decimal place), such a situation is still undesirable. Thus, for computation purposes, the older, coarsely sampled tables of spectral products have been supplemented in
40、 this revision with the concept of spectral weighting factors. To achieve these, the 10 nm spectral products defined in this and previous editions of this part of ISO 5 have been interpolated in the log domain to 1 nm intervals, using the method defined in Annex D, converted to the linear domain, an
41、d normalized to a peak value of 1. Additional sets of spectral weighting factors have then been derived from these for use with data measured at intervals greater than 1 nm and any densities calculated from these weighting factors, using the methodology defined in Annex B, will exactly match those o
42、btained with filter instruments conforming exactly to the 10 nm spectral products. Of course, the values for the 10 nm spectral weighting factors differ slightly from those for the 10 nm spectral products, when converted to the linear domain, because the computation of ISO 5 standard density (as opp
43、osed to the direct measurement of ISO 5 standard density) is a convolution of spectral weighting factors and spectral reflectance factor (or transmittance) at discrete intervals over the appropriate wavelength range. Since the spectral weighting factors include both the densitometric spectral produc
44、ts and the coefficients of a polynomial for interpolating the spectral reflectance factor or transmittance, the table entry at a given wavelength might occasionally be a small negative value. This will not result in negative densities for any typical media, nor does it imply negative spectral produc
45、ts. The sums will always be positive and the logarithms will have the appropriate magnitude for the spectrally integrated readings. It is important to note that the relative (normalized to the peak value) values for the spectral products have not changed. The interpolation to 1 nm intervals in all c
46、ases has left the 10 nm values for relative spectral products unchanged, except for a linear scaling. These data are still considered to be the primary definition of the spectral products in this part of ISO 5. Therefore, the spectral products that a filter instrument is expected to match are still
47、the same, but they have now also been defined at finer data intervals. The assumption is made that at a data interval of 1 nm, the spectral products can also be used as weighting factors for computation from spectral data recorded at, or interpolated to, that same spectral resolution. However, for p
48、ractical work, where the spectral data are usually sampled more coarsely than this, weighting factors have been calculated from these 1 nm tables. Such an approach is consistent with more recent practice in colorimetry and provides the “best” approximation to calculations made with finer resolution
49、data. These weighting functions will also provide data that are consistent with those made with a “filter” instrument conforming to the 10 nm spectral products defined in this part of ISO 5. Thus it is recommended that the weighting factors, rather than the spectral products, are to be used when calculating ISO 5 standard density from spectral reflectance factor or transmittance data collected by practical instruments at 10 nm or 20 nm wavelength intervals.
