ISO 14981:2000
(Main)Graphic technology — Process control — Optical, geometrical and metrological requirements for reflection densitometers for graphic arts use
Graphic technology — Process control — Optical, geometrical and metrological requirements for reflection densitometers for graphic arts use
Technologie graphique — Contrôle du processus — Exigences optiques, géométriques et métrologiques relatives aux densitomètres par réflexion utilisés dans l'industrie graphique
Grafična tehnologija - Vodenje procesov - Optične, geometrijske in meroslovne zahteve za refleksijske denzitometre v grafični dejavnosti
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INTERNATIONAL ISO
STANDARD 14981
First edition
2000-09-15
Graphic technology — Process control —
Optical, geometrical and metrological
requirements for reflection densitometers
for graphic arts use
Technologie graphique — Contrôle du processus — Exigences optiques,
géométriques et métrologiques relatives aux densitomètres par réflexion
utilisés dans l'industrie graphique
Reference number
ISO 14981:2000(E)
©
ISO 2000
---------------------- Page: 1 ----------------------
ISO 14981:2000(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.
© ISO 2000
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.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2000 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14981:2000(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Requirements.3
4.1 Influx and efflux geometry .3
4.1.1 General.3
4.1.2 Annular influx mode .3
4.1.3 Annular efflux mode .4
4.2 Mechanical aperture and sampling aperture .5
4.3 Illuminated area.5
4.4 Spectral conditions.6
4.4.1 Influx spectrum .6
4.4.2 Spectral products .6
4.5 Calculation of reflection density from spectral data.6
4.6 Conformance.7
4.6.1 General.7
4.6.2 Linearity.7
4.6.3 Spectral conformance .7
4.6.4 Polarization.7
4.7 Documentation.7
5 Test methods.8
5.1 General.8
5.2 Adjustment .8
5.3 Spectral conditions.8
5.4 Polarization efficiency.9
6 Reporting.10
Annex A (normative) Certified reference materials (CRM) for measuring instruments with polarizing
means.11
Annex B (normative) Polarization test object .12
Bibliography.13
© ISO 2000 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 14981:2000(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14981 was prepared by Technical Committee ISO/TC 130, Graphic technology.
Annexes A and B form a normative part of this International Standard.
iv © ISO 2000 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 14981:2000(E)
Introduction
Densitometers used in the graphic arts for process control possess a number of features which are specific to the
graphic arts. Whereas the photography standards ISO 5-1 [1], ISO 5-3 and ISO 5-4 [2] are considered to be the
basis, the measuring instruments used in graphic technology require specific requirements and tolerances.
In principle, reflection densitometers and reflection colorimeters (of photoelectric or spectrophotometric type) are
both reflectometers measuring the reflectance factor of reflection copy materials. Densitometers conforming to
ISO 5 and colorimeters conforming to ISO 13655 possess a common geometry type, namely either 45/0 or 0/45. It
is also noted that reflectometers of the spectrophotometer type can, in principle, be used both as a densitometer
and as a colorimeter. The definition of the colorimeter used in this International Standard follows CIE 17.4, the
International Lighting Vocabulary. In graphic arts, the geometry 45/0 (influx at 45° and efflux at 0°), or the geometry
0/45 are preferred over that with an integrating sphere because they correspond to the usual geometry under which
glossy graphic products are being viewed to minimize the effect of gloss typically seen by the human observer, see
also ISO 13655:1996, annex E. The introduction of polarizing means is an additional measure to remove first-
surface reflection; for matt surfaces this is the only possibility.
Notwithstanding the similarities between instruments for densitometry and colorimetry, there are fundamental
differences between them: Firstly, the illuminant used in densitometry is CIE standard illuminant A whereas
ISO 13655 specifies CIE standard illuminant D for colorimetry in the graphic arts. Secondly, for the chromatic
50
colours the weighting of the reflectance factors is different between densitometry and colorimetry. Only the "visual"
weighting function, used for the densitometry of achromatic colours (such as black), is the same as that for the
tristimulus value Y in colorimetry.
The aim of colorimetry is to provide a measuring instrument response which simulates, as well as possible, the
visual characteristics of a sample as seen by the standard observer. In graphic arts, colorimetry serves mainly for
colour matching and the establishment of colour standards. The availability of inexpensive, hand held colorimeters
of the spectrophotometric or photoelectric type, with small sampling apertures, has also permitted the use of
colorimetry in process control as a complement to densitometry. This should eliminate the use of densitometers for
colour matching.
The aims of densitometry in graphic arts are the control of the ink film thickness or, more general, the control of the
amount of colorant per area, and the determination of tone values or other quantities. A distinctly different task is
the evaluation of the density ranges of colour separation input material; this type of densitometry is not covered by
this International Standard.
The concept of this International Standard is based on the general principles specified for photography in the ISO 5
series of International Standards; for the spectral products it refers to certain tables of ISO 5-3. Just as the ISO 5
series it does not directly address the end user but the densitometer manufacturer or a suitably equipped
laboratory. Directions for the end user are to be provided by ISO 13656, which will also give an overview on the
various types of densitometers.
© ISO 2000 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 14981:2000(E)
Graphic technology — Process control — Optical, geometrical and
metrological requirements for reflection densitometers for graphic
arts use
1 Scope
This International Standard specifies requirements for measuring instruments to be used for the measurement of
the reflection densities and the tone values on half-tone or continuous-tone multi-colour graphic arts reflection-copy
material.
This International Standard is applicable equally to measuring instruments that measure status density directly
using filter/bandpass limiting techniques and to measuring instruments which measure spectrally and compute
status density. This International Standard is not applicable to measuring instruments used for continuous-tone
original art.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions.
ISO 2846-1:1997, Graphic technology — Colour and transparency of ink sets for four-colour-printing — Part 1:
Sheet-fed and heat-set web offset lithographic printing.
ISO 13655:1996, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images.
ISO 13656:2000, Graphic technology — Application of reflection densitometry and colorimetry to process control or
evaluation of prints and proofs.
1�
ISO 14807:— , Photography — Method for the determination of densitometer performance specifications.
1)
ISO 15790:— , Graphic technology and photography — Reflection and transmission metrology — Certified
reference materials — Documentation and procedures for use, including determination of combined standard
uncertainty.
1� To be published.
© ISO 2000 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 14981:2000(E)
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
NOTE For quantities, the preferred unit is given together with the definition. By definition, the unit of formerly so-called
“dimensionless” quantities is 1.
3.1
achromatic (perceived) colour
colour devoid of hue, such as black and grey. For transmitting objects, the descriptions colourless or neutral are
also used [CIE 17.4, 845-2-26], [6]
NOTE In printing practice, achromatic colours can be produced either by a single ink or three chromatic inks suitably
balanced.
3.2
calibration
set of operations that establish, under specified conditions, the relationship between quantities indicated by a
measuring instrument or measuring system, or values represented by a material measure or reference material,
and the corresponding values realized by the standards [5]
NOTE Contrary to a common misconception, calibration is not the process of adjusting a measurement system such that it
produces values that are believed to be correct but may be the cause for such an action.
3.3
certified reference material
CRM
reference material, accompanied by a certificate, one or more of whose property values are certified by a
procedure which establishes traceability to an accurate realization of the unit in which the property values are
expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence
[ISO 15790]
3.4
chromatic (perceived) colour
opposite of achromatic colour [CIE 17.4, 845-02-27], [6]
NOTE The process inks cyan, magenta and yellow are the chromatic primary colour inks.
3.5
gloss suppression factor
factor by which the reflectance factor of a polarization test object is reduced by installing polarization means into
the measuring instrument
Unit: 1
3.6
illuminated area
part of the surface of the specimen that is illuminated by the illumination source
3.7
mechanical aperture
aperture created by an opaque mask used to position the measuring instrument on the specimen
3.8
process colours (for four-colour printing)
yellow, magenta, cyan and black [3]
3.9
receiver
detection means for radiation
2 © ISO 2000 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 14981:2000(E)
3.10
reflectance factor
R
ratio of the radiant or luminous flux reflected in the directions delimited by the given cone to that reflected in the
same directions by a perfect reflecting diffuser identically illuminated [CIE 17.4, 845-04-64], [6]
Unit: 1
3.11
sampling aperture
part of the sample surface determined by the angular field of sensitivity of the receiver
3.12
screen ruling; screen frequency:
number of image elements, such as dots or lines, per length in the direction which produces the highest value [3]
-1
Unit: cm
3.13
screen width
reciprocal of screen ruling [3]
Unit:µm
3.14
spectral products
�
products of the spectral power of the influx spectrum and the spectral response of the receiver, wavelength by
wavelength
Unit: 1
NOTE The spectral response of the receiver includes the photodetector and all intervening components between it and the
sampling aperture.
4 Requirements
4.1 Influx and efflux geometry
4.1.1 General
Measurement shall be made either
� with an annular (ring-shaped) illuminator and with a directional receiver which senses in the direction normal to
the sampling aperture (annular influx mode); or
� with the illumination normal to the sampling aperture and an annular receiver (annular efflux mode).
4.1.2 Annular influx mode
The illumination shall be uniform around the annulus. If the reflection characteristics of the specimen do not change
as it is rotated in its own plane, the illumination need not be uniform around the annulus.
NOTE For applications where graphic arts materials have been shown to have a slight sensitivity to directional effects the
following are suggested compromises to the requirement of annular uniformity: The influx should be coming either from two
illumination sources positioned at azimuth angles which are 90° apart, or, preferably, from more than two illumination sources,
with equally spaced azimuth angles. A directional dependence is considered to be slight, if the averages over five repeated
density measurements differ by no more than 0,03 over the directions 0°,45° and 90°.
© ISO 2000 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 14981:2000(E)
At the centre of the sampling aperture, the angular distribution of the illumination shall be at its maximum at
45° � 2° to the sampling aperture and shall be negligible at angles that differ by more than 5° from the angle of the
maximum, see Figure 1.
The receiver shall sense in the direction normal to the sampling aperture. At the centre of the sampling aperture,
the angular distribution of the receiver sensitivity shall be at its maximum no further than 2° from the normal to the
sampling aperture and shall be negligible at angles that differ by more than 5° from the angle of the maximum, see
Figure 1.
4.1.3 Annular efflux mode
The sensing by the receiver shall b
...
SLOVENSKI STANDARD
SIST ISO 14981:2002
01-november-2002
*UDILþQDWHKQRORJLMD9RGHQMHSURFHVRY2SWLþQHJHRPHWULMVNHLQPHURVORYQH
]DKWHYH]DUHIOHNVLMVNHGHQ]LWRPHWUHYJUDILþQLGHMDYQRVWL
Graphic technology -- Process control -- Optical, geometrical and metrological
requirements for reflection densitometers for graphic arts use
Technologie graphique -- Contrôle du processus -- Exigences optiques, géométriques et
métrologiques relatives aux densitomètres par réflexion utilisés dans l'industrie
graphique
Ta slovenski standard je istoveten z: ISO 14981:2000
ICS:
17.180.20 Barve in merjenje svetlobe Colours and measurement of
light
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
SIST ISO 14981:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 14981:2002
---------------------- Page: 2 ----------------------
SIST ISO 14981:2002
INTERNATIONAL ISO
STANDARD 14981
First edition
2000-09-15
Graphic technology — Process control —
Optical, geometrical and metrological
requirements for reflection densitometers
for graphic arts use
Technologie graphique — Contrôle du processus — Exigences optiques,
géométriques et métrologiques relatives aux densitomètres par réflexion
utilisés dans l'industrie graphique
Reference number
ISO 14981:2000(E)
©
ISO 2000
---------------------- Page: 3 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(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.
© ISO 2000
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.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2000 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Requirements.3
4.1 Influx and efflux geometry .3
4.1.1 General.3
4.1.2 Annular influx mode .3
4.1.3 Annular efflux mode .4
4.2 Mechanical aperture and sampling aperture .5
4.3 Illuminated area.5
4.4 Spectral conditions.6
4.4.1 Influx spectrum .6
4.4.2 Spectral products .6
4.5 Calculation of reflection density from spectral data.6
4.6 Conformance.7
4.6.1 General.7
4.6.2 Linearity.7
4.6.3 Spectral conformance .7
4.6.4 Polarization.7
4.7 Documentation.7
5 Test methods.8
5.1 General.8
5.2 Adjustment .8
5.3 Spectral conditions.8
5.4 Polarization efficiency.9
6 Reporting.10
Annex A (normative) Certified reference materials (CRM) for measuring instruments with polarizing
means.11
Annex B (normative) Polarization test object .12
Bibliography.13
© ISO 2000 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14981 was prepared by Technical Committee ISO/TC 130, Graphic technology.
Annexes A and B form a normative part of this International Standard.
iv © ISO 2000 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(E)
Introduction
Densitometers used in the graphic arts for process control possess a number of features which are specific to the
graphic arts. Whereas the photography standards ISO 5-1 [1], ISO 5-3 and ISO 5-4 [2] are considered to be the
basis, the measuring instruments used in graphic technology require specific requirements and tolerances.
In principle, reflection densitometers and reflection colorimeters (of photoelectric or spectrophotometric type) are
both reflectometers measuring the reflectance factor of reflection copy materials. Densitometers conforming to
ISO 5 and colorimeters conforming to ISO 13655 possess a common geometry type, namely either 45/0 or 0/45. It
is also noted that reflectometers of the spectrophotometer type can, in principle, be used both as a densitometer
and as a colorimeter. The definition of the colorimeter used in this International Standard follows CIE 17.4, the
International Lighting Vocabulary. In graphic arts, the geometry 45/0 (influx at 45° and efflux at 0°), or the geometry
0/45 are preferred over that with an integrating sphere because they correspond to the usual geometry under which
glossy graphic products are being viewed to minimize the effect of gloss typically seen by the human observer, see
also ISO 13655:1996, annex E. The introduction of polarizing means is an additional measure to remove first-
surface reflection; for matt surfaces this is the only possibility.
Notwithstanding the similarities between instruments for densitometry and colorimetry, there are fundamental
differences between them: Firstly, the illuminant used in densitometry is CIE standard illuminant A whereas
ISO 13655 specifies CIE standard illuminant D for colorimetry in the graphic arts. Secondly, for the chromatic
50
colours the weighting of the reflectance factors is different between densitometry and colorimetry. Only the "visual"
weighting function, used for the densitometry of achromatic colours (such as black), is the same as that for the
tristimulus value Y in colorimetry.
The aim of colorimetry is to provide a measuring instrument response which simulates, as well as possible, the
visual characteristics of a sample as seen by the standard observer. In graphic arts, colorimetry serves mainly for
colour matching and the establishment of colour standards. The availability of inexpensive, hand held colorimeters
of the spectrophotometric or photoelectric type, with small sampling apertures, has also permitted the use of
colorimetry in process control as a complement to densitometry. This should eliminate the use of densitometers for
colour matching.
The aims of densitometry in graphic arts are the control of the ink film thickness or, more general, the control of the
amount of colorant per area, and the determination of tone values or other quantities. A distinctly different task is
the evaluation of the density ranges of colour separation input material; this type of densitometry is not covered by
this International Standard.
The concept of this International Standard is based on the general principles specified for photography in the ISO 5
series of International Standards; for the spectral products it refers to certain tables of ISO 5-3. Just as the ISO 5
series it does not directly address the end user but the densitometer manufacturer or a suitably equipped
laboratory. Directions for the end user are to be provided by ISO 13656, which will also give an overview on the
various types of densitometers.
© ISO 2000 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 14981:2002
---------------------- Page: 8 ----------------------
SIST ISO 14981:2002
INTERNATIONAL STANDARD ISO 14981:2000(E)
Graphic technology — Process control — Optical, geometrical and
metrological requirements for reflection densitometers for graphic
arts use
1 Scope
This International Standard specifies requirements for measuring instruments to be used for the measurement of
the reflection densities and the tone values on half-tone or continuous-tone multi-colour graphic arts reflection-copy
material.
This International Standard is applicable equally to measuring instruments that measure status density directly
using filter/bandpass limiting techniques and to measuring instruments which measure spectrally and compute
status density. This International Standard is not applicable to measuring instruments used for continuous-tone
original art.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 5-3:1995, Photography — Density measurements — Part 3: Spectral conditions.
ISO 2846-1:1997, Graphic technology — Colour and transparency of ink sets for four-colour-printing — Part 1:
Sheet-fed and heat-set web offset lithographic printing.
ISO 13655:1996, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images.
ISO 13656:2000, Graphic technology — Application of reflection densitometry and colorimetry to process control or
evaluation of prints and proofs.
1�
ISO 14807:— , Photography — Method for the determination of densitometer performance specifications.
1)
ISO 15790:— , Graphic technology and photography — Reflection and transmission metrology — Certified
reference materials — Documentation and procedures for use, including determination of combined standard
uncertainty.
1� To be published.
© ISO 2000 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(E)
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
NOTE For quantities, the preferred unit is given together with the definition. By definition, the unit of formerly so-called
“dimensionless” quantities is 1.
3.1
achromatic (perceived) colour
colour devoid of hue, such as black and grey. For transmitting objects, the descriptions colourless or neutral are
also used [CIE 17.4, 845-2-26], [6]
NOTE In printing practice, achromatic colours can be produced either by a single ink or three chromatic inks suitably
balanced.
3.2
calibration
set of operations that establish, under specified conditions, the relationship between quantities indicated by a
measuring instrument or measuring system, or values represented by a material measure or reference material,
and the corresponding values realized by the standards [5]
NOTE Contrary to a common misconception, calibration is not the process of adjusting a measurement system such that it
produces values that are believed to be correct but may be the cause for such an action.
3.3
certified reference material
CRM
reference material, accompanied by a certificate, one or more of whose property values are certified by a
procedure which establishes traceability to an accurate realization of the unit in which the property values are
expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence
[ISO 15790]
3.4
chromatic (perceived) colour
opposite of achromatic colour [CIE 17.4, 845-02-27], [6]
NOTE The process inks cyan, magenta and yellow are the chromatic primary colour inks.
3.5
gloss suppression factor
factor by which the reflectance factor of a polarization test object is reduced by installing polarization means into
the measuring instrument
Unit: 1
3.6
illuminated area
part of the surface of the specimen that is illuminated by the illumination source
3.7
mechanical aperture
aperture created by an opaque mask used to position the measuring instrument on the specimen
3.8
process colours (for four-colour printing)
yellow, magenta, cyan and black [3]
3.9
receiver
detection means for radiation
2 © ISO 2000 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(E)
3.10
reflectance factor
R
ratio of the radiant or luminous flux reflected in the directions delimited by the given cone to that reflected in the
same directions by a perfect reflecting diffuser identically illuminated [CIE 17.4, 845-04-64], [6]
Unit: 1
3.11
sampling aperture
part of the sample surface determined by the angular field of sensitivity of the receiver
3.12
screen ruling; screen frequency:
number of image elements, such as dots or lines, per length in the direction which produces the highest value [3]
-1
Unit: cm
3.13
screen width
reciprocal of screen ruling [3]
Unit:µm
3.14
spectral products
�
products of the spectral power of the influx spectrum and the spectral response of the receiver, wavelength by
wavelength
Unit: 1
NOTE The spectral response of the receiver includes the photodetector and all intervening components between it and the
sampling aperture.
4 Requirements
4.1 Influx and efflux geometry
4.1.1 General
Measurement shall be made either
� with an annular (ring-shaped) illuminator and with a directional receiver which senses in the direction normal to
the sampling aperture (annular influx mode); or
� with the illumination normal to the sampling aperture and an annular receiver (annular efflux mode).
4.1.2 Annular influx mode
The illumination shall be uniform around the annulus. If the reflection characteristics of the specimen do not change
as it is rotated in its own plane, the illumination need not be uniform around the annulus.
NOTE For applications where graphic arts materials have been shown to have a slight sensitivity to directional effects the
following are suggested compromises to the requirement of annular uniformity: The influx should be coming either from two
illumination sources positioned at azimuth angles which are 90° apart, or, preferably, from more than two illumination sources,
with equally spaced azimuth angles. A directional dependence is considered to be slight, if the averages over five repeated
density measurements differ by no more than 0,03 over the directions 0°,45° and 90°.
© ISO 2000 – All rights reserved 3
---------------------- Page: 11 ----------------------
SIST ISO 14981:2002
ISO 14981:2000(E)
At the centre of the sampling aperture, the angular distribution o
...
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