SIST ISO 5-2:2010
Photography and graphic technology - Density measurements - Part 2: Geometric conditions for transmittance density
Photography and graphic technology - Density measurements - Part 2: Geometric conditions for transmittance density
This part of ISO 5 specifies the geometric conditions for measuring ISO 5 standard diffuse and f/4,5 and f/1,6 projection transmittance densities. ISO 5 standard diffuse density is primarily applicable to measurements of photographic images to be viewed on a transparency illuminator, or viewing box, to be contact printed, or to be projected with a system employing diffuse illumination. ISO 5 standard projection density is primarily applicable to measurements of photographic images to be projected with systems employing optical condensers. Although primarily intended for the measurement of photographic images, the densitometric methods specified in this part of ISO 5 are often applied to optical filters and other transparent materials.
Photographie et technologie graphique - Mesurages de la densité - Partie 2: Conditions géométriques pour la densité de transmittance
Fotografija in grafična tehnologija - Merjenje optične gostote - 2. del: Geometrijski pogoji za gostoto pri transmisiji
Ta del ISO 5 določa geometrijske pogoje za merjenje difuzne gostote po standardu ISO 5 ter projekcijskih gostot pri transmisiji f/4,5 in f/1,6. Difuzna gostota po standardu ISO 5 velja predvsem za meritve fotografskih slik, ki se gledajo na osvetljevalniku ali opazovalni škatli za kontaktno tiskanje ali projiciranje s sistemom, ki uporablja difuzno osvetljevanje. Projekcijska gostota po standardu ISO 5 velja predvsem za meritve fotografskih slik, ki se projicirajo s sistemi, ki uporabljajo optične kondenzatorje. Čeprav so denzitometrične metode, določene v tem delu ISO 5, namenjene predvsem merjenju fotografskih slik, se pogosto uporabljajo za optične filtre in druge prosojne materiale.
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 5-2
Fifth edition
2009-12-01
Photography and graphic technology —
Density measurements —
Part 2:
Geometric conditions for transmittance
density
Photographie et technologie graphique — Mesurages de la densité —
Partie 2: Conditions géométriques pour la densité de transmittance
Reference number
ISO 5-2:2009(E)
©
ISO 2009
---------------------- Page: 1 ----------------------
ISO 5-2:2009(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2009 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 5-2:2009(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Coordinate system, terminology and symbols .2
5 Distinction between ideal and realized parameters.2
6 Requirements for ISO 5 standard diffuse transmittance density.2
6.1 Geometric modes .2
6.2 Sampling aperture.3
6.3 Diffuse distribution.5
6.4 Directional distribution .5
6.5 Designation .6
7 Requirements for ISO 5 standard projection transmittance density .6
7.1 Geometric modes .6
7.2 Sampling aperture.6
7.3 Directional distributions .7
7.4 Designation .7
8 Conformance testing.7
Annex A (normative) Diffusion coefficient.8
Annex B (normative) Determining conformance with tolerances.11
Annex C (informative) Unmatched influx and efflux angles.12
Bibliography.13
© ISO 2009 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 5-2:2009(E)
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 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 matters of electrotechnical 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 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 identifying any or all such patent rights.
ISO 5-2 was prepared by ISO/TC 42, Photography, and ISO/TC 130 Graphic technology, in a Joint Working
Group.
This fifth edition cancels and replaces the fourth edition (ISO 5-2:2001), which has been technically revised.
This technical revision introduces the concept of ideal and practical conditions. 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 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 density
iv © ISO 2009 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 5-2:2009(E)
Introduction
This part of ISO 5 specifies the geometric conditions for transmittance densitometry, primarily (but not
exclusively) as practised in black-and-white and colour photography and graphic technology. This part of
ISO 5 is intended to specify geometrical conditions for the measurement of optical densities that are close to
those used in practice. Diffuse transmittance densities are, among other things, relevant for contact printing
and rating films on viewing boxes. Viewing films on light boxes is one of the most important applications where
diffuse transmittance densities are relevant. Therefore, the specified conditions for the measurement of diffuse
transmittance densities consider the properties of viewing boxes concerning diffusivity and the spectral
reflectance factor. Another important application is the measurement of the diffuse transmittance density and
hence the opaque area percentage of lithography-type black-and-white films for graphic technology. This part
of ISO 5 also describes the geometric conditions for two types of projection density. The spectral conditions
are specified in ISO 5-3.
The primary change between the first edition of this part of ISO 5 (published in 1974) and the second edition
(published in 1985) was the replacement of the integrating sphere method with a diffuser (typically “opal
glass”) as the basis for specifying ISO 5 standard diffuse transmittance density. Although any means of
diffusion that meets the specifications of this part of ISO 5 can be used, the method is often denoted simply by
the words “opal glass” in order to differentiate it from the integrating sphere method. Slightly smaller density
values are generally obtained compared to those based on the integrating sphere method because of inter-
reflections between the opal glass and the specimen. The effect is dependent on the reflectance
characteristics of the opal glass and the surface of the specimen facing the diffuser.
Diffuse transmittance density is a measure of the modulation of light by a film that is diffusely irradiated on one
side and viewed from the other, as when a film is viewed on a diffuse transparency illuminator. The geometric
conditions of projection with diffuse illumination are nearly equivalent to the conditions of viewing a film on a
diffuse illuminator, the projection lens taking the place of the eye. When film is on a diffuse illuminator or in
contact with a print material, light is inter-reflected between the film and the nearby surface. This inter-
reflection affects the density and is best taken into account in a measuring instrument by the use of an opal-
glass diffuser or integrator, rather than an integrating sphere. Apart from this fundamental reason for using
densitometers employing opal-glass diffusers, such instruments are preferred because they are more durable
and more convenient to manufacture and use.
Projection density is a measure of the modulation of light by a film that is regularly illuminated on one side and
is projected by way of a regular collection system. Equipment employing optical condensers is used to view
microfilm, motion pictures, and slides, and to make projection prints. The conditions defined in this part of
ISO 5 for projection density simulate the geometric conditions affecting the transmitting characteristics of a
small area on a negative or transparency at the centre of the frame of a typical projection system employing
condensers. The area under consideration can be defined by a small opening, known as the “sampling
aperture”, in an otherwise opaque sheet in the frame.
The measured density depends on the half-angle of the cone of incident rays and the half-angle subtended by
the projection lens at the sampling aperture. These half-angles can be indicated either in degrees or by
ƒ-numbers. Since the ƒ-number is usually marked on projection lenses, the two types of ISO 5 standard
projection density specified in this part of ISO 5 are identified by ƒ-numbers, namely ƒ/4,5 and ƒ/1,6. The ƒ/4,5
type is frequently used, since it is representative of microfilm readers. The ƒ/1,6 type is considered
representative of motion-picture projectors.
Significant changes from the fourth edition of this part of ISO 5 are explained below.
a) The terminology “transmission density” has been replaced by the term “transmittance density” for both
diffuse and projection densities. Both densities require measurements relative to the incident flux (influx),
and therefore the regular or diffuse transmittance of the specimen is measured. As explained in ISO 5-1,
the correct density term corresponding to regular transmittance is “transmittance density”.
© ISO 2009 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 5-2:2009(E)
b) A distinction is made between ideal and realized parameters for transmittance density. The definition of
ISO 5 standard transmittance density is based upon ideal values specified for each parameter. However,
actual instruments require reasonable tolerances for physical parameters, which are specified by the
realizable parameters.
vi © ISO 2009 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 5-2:2009(E)
Photography and graphic technology — Density
measurements —
Part 2:
Geometric conditions for transmittance density
1 Scope
This part of ISO 5 specifies the geometric conditions for measuring ISO 5 standard diffuse and ƒ/4,5 and ƒ/1,6
projection transmittance densities.
ISO 5 standard diffuse density is primarily applicable to measurements of photographic images to be viewed
on a transparency illuminator, or viewing box, to be contact printed, or to be projected with a system
employing diffuse illumination.
ISO 5 standard projection density is primarily applicable to measurements of photographic images to be
projected with systems employing optical condensers.
Although primarily intended for the measurement of photographic images, the densitometric methods
specified in this part of ISO 5 are often applied to optical filters and other transparent materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5-1, Photography and graphic technology — Density measurements — Part 1: Geometry and functional
notation
ISO 5-3, Photography and graphic technology — Density measurements — Part 3: Spectral conditions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5-1 and the following apply.
3.1
diffusion coefficient
β
dc
measure of the diffusivity of the illuminating or receiving system
NOTE See Annex A.
© ISO 2009 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 5-2:2009(E)
3.2
transmittance
τ
ratio of the transmitted flux to the incident flux under specified geometrical and spectral conditions of
measurement
NOTE 1 In practical instruments for transmittance measurements, the incident flux is defined by the combination of all
of the components that are placed before the reference plane (influx), so the incident flux is provided by the surface of the
opal diffuser for diffuse transmittance and by the film gate for projection density.
NOTE 2 Adapted from ASTM E284.
[ISO 5-1:2009, definition 3.22]
3.3
transmittance density
D
τ
negative logarithm to the base 10 of the transmittance
NOTE The subscript is the lower case Greek letter tau.
[ISO 5-1:2009, definition 3.23]
4 Coordinate system, terminology and symbols
The coordinate system, terminology, and symbols described in ISO 5-1 are used in this part of ISO 5 as a
basis for specifying the geometric conditions for ISO 5 standard transmittance density measurements.
5 Distinction between ideal and realized parameters
The unambiguous definition of ISO 5 standard density requires that geometric, as well as spectral, parameters
be exactly specified. However, the practical design and manufacture of instruments requires that reasonable
tolerances be allowed for physical parameters. The definition of ISO 5 standard transmittance density shall be
based on the ideal value specified for each parameter. The tolerances shown for the realized parameter
values represent allowable variations of these standard parameters, which for many applications have an
effect of less than 0,01 on the density values resulting from measurements made with instruments. A method
for determining conformance of a realized parameter with the tolerances is given in Annex B.
6 Requirements for ISO 5 standard diffuse transmittance density
6.1 Geometric modes
Diffuse transmittance density measurements may be made with two equivalent measurement geometries. In
the “diffuse influx mode”, the geometry of the illuminator is diffuse and the geometry of the receiver is
directional, while in the “diffuse efflux mode”, the geometry of the illuminator is directional and the geometry of
the receiver is diffuse. These modes are defined in Figure 1. A diffuse illuminator projects radiant flux onto the
sampling aperture from all directions within the hemisphere, while a diffuse receiver collects radiant flux
transmitted by the sampling aperture in all directions within the hemisphere. The modes can be described in
terms of specified diffuse and directional distributions of illumination radiance or receiver responsivity,
depending on the mode. The cone half-angle, κ, is the angle between the angle of illumination or view and the
marginal ray. A cone half-angle of 90° indicates that the illuminator or receiver has a diffuse geometry.
Referring to the cone half-angles shown in Figure 1, the ideal angles of illumination and view and half-angles
for the diffuse influx mode are θ = 0°, κ = 90°, and θ = 0°, κ = 10°. For the diffuse efflux mode, the ideal
i i t t
angles of view and illumination and half-angles are θ = 0°, κ = 90°, and θ = 0°, κ = 10°.
t t i i
2 © ISO 2009 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 5-2:2009(E)
The realized angles of illumination and view and half-angles for the diffuse influx mode are θ = 0° ± 2°,
i
κ = 90°, and θ = 0° ± 2° κ = 10° ± 2°. For the diffuse efflux mode, the realized angles of view and illumination
i t t
and half-angles are θ = 0° ± 2°, κ = 90°, and θ = 0° ± 2°, κ = 10° ± 2°.
t t i i
NOTE The 90° specification implies physical contact between the specimen and the diffuse illuminator or receiver.
For diffuse density measurement with diffuse influx: κ = 90° and κ = 10°.
i t
For diffuse density measurement with diffuse efflux: κ = 10° and κ = 90°.
i t
For projection density measurements, for ƒ/4,5: κ = κ = 6,4°.
i t
For projection density measurements, for ƒ/1,6: κ = κ = 18,2°.
i t
Key
1 influx geometry
2 efflux geometry
3 sampling aperture
4 aperture simulating the entrance pupil of projection lens
5 point O
Figure 1 — Geometry for ISO 5 standard transmittance density measurements
6.2 Sampling aperture
The extent and shape of the area on which density is measured is the sampling aperture. Physically, the
sampling aperture is realized by a diaphragm, which shall be in contact with the specimen to be measured.
Figure 2 shows the four combinations which may be applied: two for the diffuse influx mode and two for the
diffuse efflux mode. All other combinations are excluded.
NOTE 1 Figure 2 shows, for combinations b) and d), that the opaque material of the diaphragm constitutes a smooth
surface with the diffusing material. This can be obtained by grinding the opal glass and filling the recess with an
appropriate opaque material. Since these combinations are rather costly, combinations a) and c) will be preferred in
practice.
© ISO 2009 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 5-2:2009(E)
a) Diffuse influx mode 1 c) Diffuse efflux mode 1
b) Diffuse influx mode 2 d) Diffuse efflux mode 2
Key
1 diaphragm
2 specimen
3 opal glass
Figure 2 — Geometrical arrangement of the diaphragm for diffuse influx mode and diffuse efflux mode
In combinations a) and d) of Figure 2, the diaphragm is part of the receiver, and the illuminator region (i.e. the
area over which the specimen is illuminated) shall be larger than the size of the diaphragm. In combinations b)
and c) of Figure 2, the diaphragm is part of the illuminator, and the receiver region (i.e. the area
...
SLOVENSKI STANDARD
SIST ISO 5-2:2010
01-maj-2010
1DGRPHãþD
SIST ISO 5-2:2002
)RWRJUDILMDLQJUDILþQDWHKQRORJLMD0HUMHQMHRSWLþQHJRVWRWHGHO *HRPHWULMVNL
SRJRML]DJRVWRWRSULWUDQVPLVLML
Photography and graphic technology - Density measurements - Part 2: Geometric
conditions for transmittance density
Photographie et technologie graphique - Mesurages de la densité - Partie 2: Conditions
géométriques pour la densité de transmittance
Ta slovenski standard je istoveten z: ISO 5-2:2009
ICS:
37.040.01 Fotografija na splošno Photography in general
SIST ISO 5-2:2010 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 5-2:2010
---------------------- Page: 2 ----------------------
SIST ISO 5-2:2010
INTERNATIONAL ISO
STANDARD 5-2
Fifth edition
2009-12-01
Photography and graphic technology —
Density measurements —
Part 2:
Geometric conditions for transmittance
density
Photographie et technologie graphique — Mesurages de la densité —
Partie 2: Conditions géométriques pour la densité de transmittance
Reference number
ISO 5-2:2009(E)
©
ISO 2009
---------------------- Page: 3 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2009 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Coordinate system, terminology and symbols .2
5 Distinction between ideal and realized parameters.2
6 Requirements for ISO 5 standard diffuse transmittance density.2
6.1 Geometric modes .2
6.2 Sampling aperture.3
6.3 Diffuse distribution.5
6.4 Directional distribution .5
6.5 Designation .6
7 Requirements for ISO 5 standard projection transmittance density .6
7.1 Geometric modes .6
7.2 Sampling aperture.6
7.3 Directional distributions .7
7.4 Designation .7
8 Conformance testing.7
Annex A (normative) Diffusion coefficient.8
Annex B (normative) Determining conformance with tolerances.11
Annex C (informative) Unmatched influx and efflux angles.12
Bibliography.13
© ISO 2009 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
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 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 matters of electrotechnical 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 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 identifying any or all such patent rights.
ISO 5-2 was prepared by ISO/TC 42, Photography, and ISO/TC 130 Graphic technology, in a Joint Working
Group.
This fifth edition cancels and replaces the fourth edition (ISO 5-2:2001), which has been technically revised.
This technical revision introduces the concept of ideal and practical conditions. 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 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 density
iv © ISO 2009 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
Introduction
This part of ISO 5 specifies the geometric conditions for transmittance densitometry, primarily (but not
exclusively) as practised in black-and-white and colour photography and graphic technology. This part of
ISO 5 is intended to specify geometrical conditions for the measurement of optical densities that are close to
those used in practice. Diffuse transmittance densities are, among other things, relevant for contact printing
and rating films on viewing boxes. Viewing films on light boxes is one of the most important applications where
diffuse transmittance densities are relevant. Therefore, the specified conditions for the measurement of diffuse
transmittance densities consider the properties of viewing boxes concerning diffusivity and the spectral
reflectance factor. Another important application is the measurement of the diffuse transmittance density and
hence the opaque area percentage of lithography-type black-and-white films for graphic technology. This part
of ISO 5 also describes the geometric conditions for two types of projection density. The spectral conditions
are specified in ISO 5-3.
The primary change between the first edition of this part of ISO 5 (published in 1974) and the second edition
(published in 1985) was the replacement of the integrating sphere method with a diffuser (typically “opal
glass”) as the basis for specifying ISO 5 standard diffuse transmittance density. Although any means of
diffusion that meets the specifications of this part of ISO 5 can be used, the method is often denoted simply by
the words “opal glass” in order to differentiate it from the integrating sphere method. Slightly smaller density
values are generally obtained compared to those based on the integrating sphere method because of inter-
reflections between the opal glass and the specimen. The effect is dependent on the reflectance
characteristics of the opal glass and the surface of the specimen facing the diffuser.
Diffuse transmittance density is a measure of the modulation of light by a film that is diffusely irradiated on one
side and viewed from the other, as when a film is viewed on a diffuse transparency illuminator. The geometric
conditions of projection with diffuse illumination are nearly equivalent to the conditions of viewing a film on a
diffuse illuminator, the projection lens taking the place of the eye. When film is on a diffuse illuminator or in
contact with a print material, light is inter-reflected between the film and the nearby surface. This inter-
reflection affects the density and is best taken into account in a measuring instrument by the use of an opal-
glass diffuser or integrator, rather than an integrating sphere. Apart from this fundamental reason for using
densitometers employing opal-glass diffusers, such instruments are preferred because they are more durable
and more convenient to manufacture and use.
Projection density is a measure of the modulation of light by a film that is regularly illuminated on one side and
is projected by way of a regular collection system. Equipment employing optical condensers is used to view
microfilm, motion pictures, and slides, and to make projection prints. The conditions defined in this part of
ISO 5 for projection density simulate the geometric conditions affecting the transmitting characteristics of a
small area on a negative or transparency at the centre of the frame of a typical projection system employing
condensers. The area under consideration can be defined by a small opening, known as the “sampling
aperture”, in an otherwise opaque sheet in the frame.
The measured density depends on the half-angle of the cone of incident rays and the half-angle subtended by
the projection lens at the sampling aperture. These half-angles can be indicated either in degrees or by
ƒ-numbers. Since the ƒ-number is usually marked on projection lenses, the two types of ISO 5 standard
projection density specified in this part of ISO 5 are identified by ƒ-numbers, namely ƒ/4,5 and ƒ/1,6. The ƒ/4,5
type is frequently used, since it is representative of microfilm readers. The ƒ/1,6 type is considered
representative of motion-picture projectors.
Significant changes from the fourth edition of this part of ISO 5 are explained below.
a) The terminology “transmission density” has been replaced by the term “transmittance density” for both
diffuse and projection densities. Both densities require measurements relative to the incident flux (influx),
and therefore the regular or diffuse transmittance of the specimen is measured. As explained in ISO 5-1,
the correct density term corresponding to regular transmittance is “transmittance density”.
© ISO 2009 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
b) A distinction is made between ideal and realized parameters for transmittance density. The definition of
ISO 5 standard transmittance density is based upon ideal values specified for each parameter. However,
actual instruments require reasonable tolerances for physical parameters, which are specified by the
realizable parameters.
vi © ISO 2009 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 5-2:2010
INTERNATIONAL STANDARD ISO 5-2:2009(E)
Photography and graphic technology — Density
measurements —
Part 2:
Geometric conditions for transmittance density
1 Scope
This part of ISO 5 specifies the geometric conditions for measuring ISO 5 standard diffuse and ƒ/4,5 and ƒ/1,6
projection transmittance densities.
ISO 5 standard diffuse density is primarily applicable to measurements of photographic images to be viewed
on a transparency illuminator, or viewing box, to be contact printed, or to be projected with a system
employing diffuse illumination.
ISO 5 standard projection density is primarily applicable to measurements of photographic images to be
projected with systems employing optical condensers.
Although primarily intended for the measurement of photographic images, the densitometric methods
specified in this part of ISO 5 are often applied to optical filters and other transparent materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5-1, Photography and graphic technology — Density measurements — Part 1: Geometry and functional
notation
ISO 5-3, Photography and graphic technology — Density measurements — Part 3: Spectral conditions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5-1 and the following apply.
3.1
diffusion coefficient
β
dc
measure of the diffusivity of the illuminating or receiving system
NOTE See Annex A.
© ISO 2009 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
3.2
transmittance
τ
ratio of the transmitted flux to the incident flux under specified geometrical and spectral conditions of
measurement
NOTE 1 In practical instruments for transmittance measurements, the incident flux is defined by the combination of all
of the components that are placed before the reference plane (influx), so the incident flux is provided by the surface of the
opal diffuser for diffuse transmittance and by the film gate for projection density.
NOTE 2 Adapted from ASTM E284.
[ISO 5-1:2009, definition 3.22]
3.3
transmittance density
D
τ
negative logarithm to the base 10 of the transmittance
NOTE The subscript is the lower case Greek letter tau.
[ISO 5-1:2009, definition 3.23]
4 Coordinate system, terminology and symbols
The coordinate system, terminology, and symbols described in ISO 5-1 are used in this part of ISO 5 as a
basis for specifying the geometric conditions for ISO 5 standard transmittance density measurements.
5 Distinction between ideal and realized parameters
The unambiguous definition of ISO 5 standard density requires that geometric, as well as spectral, parameters
be exactly specified. However, the practical design and manufacture of instruments requires that reasonable
tolerances be allowed for physical parameters. The definition of ISO 5 standard transmittance density shall be
based on the ideal value specified for each parameter. The tolerances shown for the realized parameter
values represent allowable variations of these standard parameters, which for many applications have an
effect of less than 0,01 on the density values resulting from measurements made with instruments. A method
for determining conformance of a realized parameter with the tolerances is given in Annex B.
6 Requirements for ISO 5 standard diffuse transmittance density
6.1 Geometric modes
Diffuse transmittance density measurements may be made with two equivalent measurement geometries. In
the “diffuse influx mode”, the geometry of the illuminator is diffuse and the geometry of the receiver is
directional, while in the “diffuse efflux mode”, the geometry of the illuminator is directional and the geometry of
the receiver is diffuse. These modes are defined in Figure 1. A diffuse illuminator projects radiant flux onto the
sampling aperture from all directions within the hemisphere, while a diffuse receiver collects radiant flux
transmitted by the sampling aperture in all directions within the hemisphere. The modes can be described in
terms of specified diffuse and directional distributions of illumination radiance or receiver responsivity,
depending on the mode. The cone half-angle, κ, is the angle between the angle of illumination or view and the
marginal ray. A cone half-angle of 90° indicates that the illuminator or receiver has a diffuse geometry.
Referring to the cone half-angles shown in Figure 1, the ideal angles of illumination and view and half-angles
for the diffuse influx mode are θ = 0°, κ = 90°, and θ = 0°, κ = 10°. For the diffuse efflux mode, the ideal
i i t t
angles of view and illumination and half-angles are θ = 0°, κ = 90°, and θ = 0°, κ = 10°.
t t i i
2 © ISO 2009 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
The realized angles of illumination and view and half-angles for the diffuse influx mode are θ = 0° ± 2°,
i
κ = 90°, and θ = 0° ± 2° κ = 10° ± 2°. For the diffuse efflux mode, the realized angles of view and illumination
i t t
and half-angles are θ = 0° ± 2°, κ = 90°, and θ = 0° ± 2°, κ = 10° ± 2°.
t t i i
NOTE The 90° specification implies physical contact between the specimen and the diffuse illuminator or receiver.
For diffuse density measurement with diffuse influx: κ = 90° and κ = 10°.
i t
For diffuse density measurement with diffuse efflux: κ = 10° and κ = 90°.
i t
For projection density measurements, for ƒ/4,5: κ = κ = 6,4°.
i t
For projection density measurements, for ƒ/1,6: κ = κ = 18,2°.
i t
Key
1 influx geometry
2 efflux geometry
3 sampling aperture
4 aperture simulating the entrance pupil of projection lens
5 point O
Figure 1 — Geometry for ISO 5 standard transmittance density measurements
6.2 Sampling aperture
The extent and shape of the area on which density is measured is the sampling aperture. Physically, the
sampling aperture is realized by a diaphragm, which shall be in contact with the specimen to be measured.
Figure 2 shows the four combinations which may be applied: two for the diffuse influx mode and two for the
diffuse efflux mode. All other combinations are excluded.
NOTE 1 Figure 2 shows, for combinations b) and d), that the opaque material of the diaphragm constitutes a smooth
surface with the diffusing material. This can be obtained by grinding the opal glass and filling the recess with an
appropriate opaque material. Since these combinations are rather costly, combinations a) and c) will be preferred in
practice.
© ISO 2009 – All rights reserved 3
---------------------- Page: 11 ----------------------
SIST ISO 5-2:2010
ISO 5-2:2009(E)
a) Diffuse influx mode 1 c) Diffuse efflux mode 1
b) Diffuse influx mode 2 d)
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.