ISO 18944:2014

INTERNATIONAL ISO
STANDARD 18944
Second edition
2014-06-01
Imaging materials — Reflection colour
photographic prints — Test print
construction and measurement
Matériaux pour l’image — Réflexion des impressions photographiques
en couleurs — Mesurage et construction d’une impression d’essai
Reference number
©
ISO 2014
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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Published in Switzerland
ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 3
5 Digital file preparation . 3
5.1 Digital test file usage situations . 3
5.2 Digital test file general requirements . 4
5.3 Preparing the digital test file for an image print stability test . 6
5.4 Preparing the digital test file for an image forming materials stability test . 7
5.5 Target print uniformity . 8
5.6 Test chamber condition uniformity . 8
6 Generating the target prints . 9
6.1 Digital print preparation . 9
6.2 Source preparation for conventional silver gelatine photographic materials. 9
6.3 Configuring the printing system and generating the target prints . 9
6.4 Conditioning the prints after printing .10
7 Target print holding and measurement conditions .11
7.1 Measurement timing .11
7.2 Holding and measurement conditions .11
Annex A (normative) Required sRGB encoded patch values for image print stability test target and
patch selection process .14
Annex B (informative) Method of interpolation for step wedge exposures.24
Annex C (informative) How to build the digital test file and print “image print stability”
target print .25
Annex D (informative) How to build the digital test file and print “the image forming materials
stability test” target print .27
Annex E (informative) Method to limit measurement error .28
Bibliography .31
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 18944:2012), which has been technically
revised.
iv © ISO 2014 – All rights reserved

Introduction
This International Standard is one of a series of International Standards prepared by ISO/TC 42 on the
physical properties, stability and permanence of imaging materials.
This International Standard provides constraints on factors pertaining to target print preparation and
resulting target print measurement which can cause a confounding test-process-induced variation in
measured colour values and densities.
The requirements in this International Standard are intended to be used with test methods that produce
test data to be shared publicly, with the aim that test results can be duplicated in an alternate test
facility.
Topics addressed include:
— description of test types (image print stability test versus image forming materials stability test);
— digital file preparation;
— digital test file usage;
— addressing target print uniformity;
— managing test equipment non-uniformity;
— printing system configuration and control;
— test print conditioning;
— measurement timing and measurement conditions;
— required sRGB encoded patch set for image print stability test target and the corresponding patch
selection process;
— informative guidance for test file construction and use;
— informative guidance on statistical approaches to minimize measurement error.
INTERNATIONAL STANDARD ISO 18944:2014(E)
Imaging materials — Reflection colour photographic prints
— Test print construction and measurement
IMPORTANT — The electronic file of this International Standard contains colours which are
considered to be useful for the correct understanding of this International Standard. Users
should therefore consider printing with a colour printer.
1 Scope
This International Standard specifies requirements and recommendations for the digital test file
content, number of print replicates, printer setups and printing procedures that are used to generate
target prints for test method standards and specifications for image stability in the context of reflection
colour photographic prints.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 5-3, Photography and graphic technology — Density measurements — Part 3: Spectral conditions
ISO 5-4, Photography and graphic technology — Density measurements — Part 4: Geometric conditions for
reflection density
ISO 2471:2008, Paper and board — Determination of opacity (paper backing) — Diffuse reflectance method
ISO 12640-3:2007, Graphic technology — Prepress digital data exchange — Part 3: CIELAB standard colour
image data (CIELAB/SCID)
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ISO 18941, Imaging materials — Colour reflection prints — Test method for ozone gas fading stability
IEC 61966-2-1, Multimedia systems and equipment — Colour measurement and management — Part 2-1:
Colour management — Default RGB colour space — sRGB
1)
TIFF, Revision 6.0. Adobe Systems Incorporated 1992
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
CMYK printer
printer configured to accept digital files with colours encoded in terms of CMYK printer colourants
3.2
image forming materials stability test
test to evaluate the print stability of the component materials that comprise image prints, intended
for manufacturers who are designing new colourants or for customers who are specifying colourant
characteristics
1) Available at http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
3.3
image print stability test
test to evaluate the print stability of images printed in end-user-typical fashion
3.4
operational control point
set point for equilibrium conditions measured at sensor location(s) in an exposure device
[SOURCE: ASTM G113 — modified]
3.5
operational fluctuations
positive and negative deviations from the setting of the operational control set point during equilibrium
conditions in a laboratory-accelerated weathering device
Note 1 to entry: The operational fluctuations are the result of unavoidable machine variables and do not include
measurement uncertainty. The operational fluctuations apply only at the location of the control sensor and do not
imply uniformity of conditions throughout the test chamber.
[SOURCE: ASTM G113 — modified]
3.6
operational uniformity
range around the operational control point for measured parameters within the intended exposure area
within the limits of intended operational range
Note 1 to entry: Operational uniformity evaluates the measured parameters throughout the test chamber so that
regions of the test chamber can be determined to comply within the required limits of the measured parameter
operating aim.
[SOURCE: ASTM G113 — modified]
3.7
OD
optical density
3.8
printing system
system to generate reflection colour photographic prints, including printing colorants, printing
equipment hardware and software, and typically the print media
3.9
PVR
Patch Value Rating used in the patch selection process equations
3.10
reflection colour photographic print
positive photographic image intended to be viewed with reflected light, made using colourants such as
cyan, magenta, and yellow
[SOURCE: ISO 18913 — modified]
3.11
RGB printer
printer configured to accept digital files with RGB printer-independent encoded colours and apply a
conversion to obtain printer colourant code values
2 © ISO 2014 – All rights reserved

3.12
uncertainty (of measurement)
parameter associated with the result of a measurement that characterizes the dispersion of the values
that could be reasonably attributed to the measurand
Note 1 to entry: The parameter may be, for example, a standard deviation (or a given multiple of it), or the half-
width of an interval having a stated confidence level. Uncertainty of measurement comprises, in general, many
components. Some of these components may be evaluated from statistical distribution of the results of series of
measurements and can be characterized by experimental standard deviations. The other components, which can
also be characterized by standard deviations, are evaluated from assumed probability distributions based on
experience or other information. It is understood that the result of the measurement is the best estimate of the
value of the measurand, and that all components of uncertainty, including those arising from systematic effects,
such as components associated with corrections and reference standards, contribute to the dispersion.
[SOURCE: ASTM G113 — modified]
4 Requirements
This International Standard specifies constraints on factors pertaining to target print preparation
and resulting target print measurement which can cause confounding test-process-induced variation
of measured colour values and densities. The requirements of this International Standard shall be
applied in test methods that are used to make life expectancy claims, such as time-based print lifetime
claims, either comparative or absolute, in accordance with the applicable International Standard(s) for
specification of print life.
The requirements of this International Standard should be applied with image stability test methods
when those test methods are used to report stand-alone absolute or comparative stability of image
materials with respect to the specific failure mode of the test method standard.
In alternative test situations, when the conditions and constraints set forth in this International
Standard are not followed, then the test report of that test method result shall include a statement
of each condition that differs from the requirements of this International Standard. Caution shall be
used when comparing test results for different materials and for different target print preparation
and measurement conditions. Comparisons shall only be made when using equipment with matching
specifications, under matching test conditions.
This International Standard has not been tested with printing systems having the capability to deposit
analogue variations in colourant thickness, e.g. an analogue CMYK press, and is not suitable as is for use
with such printing systems.
5 Digital file preparation
5.1 Digital test file usage situations
For general testing purposes, users of this International Standard are free to choose whatever target
patches and starting densities they feel are appropriate for their testing needs. Applicable International
Standard(s) for specification of print life may require the use of specific targets and starting densities.
Reference target prints should be included in every exposure test to track consistency of the test
procedures, as well as to detect unintended changes in test conditions.
NOTE 1 See ASTM G156.
The target prints of this International Standard can be used for two kinds of image stability testing:
a) a printing system test for image print stability, including substrate discolouration, or
b) a materials test for image forming materials stability (colourant stability, substrate discolouration
and any interaction between them).
The digital test file is adapted and the target prints are generated differently for these two cases. After
the digital test file is printed, when subjected to the test method standards, the target prints are treated
identically.
The image print stability test assesses the stability of images printed in end-user-typical fashion. The test
file in this case is encoded in standard sRGB, as defined in IEC 61966-2-1.
NOTE 2 The sRGB colour encoding is widely used in digital photography. This is a particular RGB encoding
that has a standardized visual colour meaning for each RGB code value. The standardized colour meaning for
each sRGB code value means that “sky blue” and “grass green”, etc. are represented by certain RGB code values.
Because the sRGB colour encoding is well known, printers that print digital photographs can be configured to
print sRGB encoded images. Printing sRGB code values that have standardized colour meanings of cyan, magenta,
yellow, red, green, blue and neutral will result in target print patches that have colourant proportions similar to
consumer image prints of those colours produced through the specific printing system.
Real world image print stability is a function of combinations of colourants in real images. Colourant
proportion significantly impacts the results of the stability tests. Using colourant proportions similar
to those in consumer prints for specific well defined colours improves estimation of consumer image
stability. The print colourant proportions in the image stability target print will be slightly different
for different printing systems, however in each case the target print is a realistic representation of the
colourant proportions in real photos printed via those printers.
Printing the primaries and secondaries and neutrals does not cover all possible kinds of inks that a
printer may contain. Testing for additional colourants is a recommended extension for both the image
print and image forming materials.
The image forming materials stability test assesses the stability of the component materials that comprise
the prints. Care is taken to isolate the materials from influences of the printing system hardware and
software as far as is possible.
NOTE 3 This test is intended for manufacturers who are designing new inks or for customers who are specifying
ink characteristics, and require testing on individual components.
5.2 Digital test file general requirements
Printing systems can be configured either to accept digital files with colours encoded for the printer
colourants, such as CMYK, or to accept digital files with colours defined using a printer-independent
encoding, such as sRGB. Printers that are configured to accept an RGB printer-independent encoding can
process the conversion from the input RGB to the printer colourant encoding in a proprietary manner.
These printers can be referred to as “RGB printers”. Printers that can be configured to accept (and
print without further colourant mixing) digital files with colours encoded for CMYK printer colourants
can be referred to as “CMYK printers”. The file preparation process below describes the necessary file
treatment for RGB and CMYK printers.
The digital test file of encoded colour values shall be constructed so that the target print contains areas
of uniform colour (i.e. patches) corresponding to each selected optical density (recommended 0,5; 1,0;
and 1,5 above D ). The size of each square colour patch area shall be at least 2 mm greater in length and
min
4 © ISO 2014 – All rights reserved

width than the measurement instrument aperture, plus twice the measurement instrument positioning
accuracy specification, according to the following equation:
S = K + (2 * A) + D
where
S is the minimum side length of each square colour patch area, in millimetres;
K is the constant value of 2 mm as specified in the requirement above the equation;
A is the measurement instrument “measurement positioning accuracy” specified by the instru-
ment manufacturer, in millimetres;
D is the measurement instrument “measurement aperture diameter” specified by the instru-
ment manufacturer, in millimetres.
For example, with a measurement positioning accuracy of ± 0,25 mm and a measurement aperture
diameter of 4,5 mm, the minimum allowed patch size = (2,0 + 0,50 + 4,5) mm, which is 7 mm . Spacing
between patches shall be adjusted to minimize degrading influence between patches during the testing
and measurement processes. The appropriate inter-patch spacing depends on the materials and the
equipment used.
The digital test file shall produce target print patch areas of minimum density (i.e. “paper white”).
The digital test file shall produce target print patches of selected optical densities utilizing cyan,
magenta, yellow and black (if available) printer colourant primaries, and utilizing red, green and blue
printer secondaries.
NOTE 1 Some printing processes use CMY primaries only.
The digital test file shall produce target prints with individual patches having the selected optical
densities within the required “single patch” tolerance limits, or with pairs of “bracketing patches” having
the selected optical densities within the required “bracketing patch pair” tolerance limits, according to
the requirements of Annex A. In the case of bracketing pair patches, the selected optical density values
shall be obtained using interpolation as described in Annex B.
The digital test file shall be created and maintained continuously in the tiff file format. No lossy image or
file compression shall be applied to the target file in the tiff file format. The digital image file resolution
shall be 600 dpi.
NOTE 2 Various lossy compression methods can result in slight changes to colour values, particularly at patch
edges. This in turn can result in additional undesirable mixing of colourants. At the time of publication of this
International Standard, the tiff file format provides the means to carry raster image content in digital files with
minimal host application and operating system dependence.
NOTE 3 The digital test file can be zipped using lossless compression to minimize file size for storage.
Digital test files defined in compliance with this International Standard can be designed and adapted
2)
for particular printing systems in any of the available image programs (such as Adobe Photoshop® ).
Ensure that the image resolution is 600 dpi after editing.
2) Photoshop is the trade name of a product supplied by Adobe. This information is given for the convenience of
users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products
may be used if they can be shown to lead to the same results.
5.3 Preparing the digital test file for an image print stability test
5.3.1 Constructing the digital file for an image print stability test
The image print stability digital test file shall be encoded in sRGB as defined in IEC 61966-2-1 and saved
in the tiff format with the sRGB ICC profile embedded.
NOTE 1 Even though sRGB is a standard, the ICC profiles for sRGB can differ. Retaining the original sRGB ICC
profile with the file contributes to test repeatability.
For image print stability testing, the encoded colour values of the patches in the digital test file shall
not be manipulated to control the colourant proportions in the patches of the target print. Rather, the
objective is to obtain cyan, magenta, yellow, red, green, and blue coloured patches in the target print that
are typical in a pleasing pictorial image. Pure primary colourant patches and two-colourant secondary
patches may or may not occur in the print. When subjected to an image print stability test method, the
measurable target print patch density changes can be compared to image print changes that a user
would experience. See Annex A and Annex C.
Colourant proportions in the image print stability target print are recognized as system-specific,
dependent on image processing, ICC profiles, halftoning, and other physical printer characteristics.
The image print stability test requires target prints with selected optical densities in:
a) neutral patches;
NOTE 2 Patches that are treated as neutral include white (no colourant printed), black and all values of
grey produced from R = G = B sRGB encoded patch values. Such sRGB values correspond to CIELAB values
with L* > 0, and a* and b* both equal to zero.
b) cyan, magenta, and yellow-coloured patches;
c) red, green, and blue-coloured patches;
d) D patch (i.e. “paper white”) area (used to evaluate substrate discolouration).
min
NOTE 3 Additional coloured patches, e.g. orange, and flesh tones, can also be tested, although such test patches
are not within the scope of this International Standard.
In certain cases, the printer driver software may provide an option to assign neutral code values
exclusively to the black ink. In such case, composite neutral black printed with cyan, magenta and yellow
colourants shall be used.
5.3.2 Adapting the digital file for an image print stability test — RGB printers
The image content shall be encoded in sRGB as defined in IEC 61966-2-1. An sRGB digital test file shall
be constructed using the required sRGB patch values provided in Annex A, or a selected subset of those
required sRGB patch values. Whether used in whole or in part, the sRGB code values of the patches given
in Annex A shall not be changed prior to printing.
5.3.3 Adapting the digital file for an image print stability test — CMYK printers
The image content shall be encoded in “device CMYK” that is specific to the printer under test. The device
CMYK digital test file for the specific printer under test shall be obtained from an sRGB digital test file
constructed using the required sRGB patch values provided in Annex A, or a selected subset of those
required sRGB patch values. The CMYK encoded digital test file shall be obtained for the specific printer
under test using the photo print colour management transformation method that is appropriate for
consumer users of the printer. For example, an ICC profile provided by the printing system manufacturer
and matched to the print conditions and media of the test can be used. Whether used in whole or in part,
the sRGB code values of the patches given in Annex A shall not be changed prior to conversion to CMYK
for the printer under test; and the resulting printer-specific CMYK code values shall not be changed
prior to printing.
6 © ISO 2014 – All rights reserved

When the image print stability of a specialized configuration of a printing system is being tested, e.g.
prints produced using a specialized configuration in a professional or commercial print environment,
a customized ICC profile may be used. Such a customized ICC profile shall be appropriate to produce
end-customer quality printing in the configuration under test. The use of any such ICC profile shall be
reported in the test results.
5.4 Preparing the digital test file for an image forming materials stability test
5.4.1 Constructing the digital file for an image forming materials stability test
For digital printing systems, the image forming materials stability test is used to test the stability of
the component materials that comprise digital prints. For example, one cyan dye may exhibit greater
resistance to light fade than another. When testing for primary colourant stability (e.g. C, M, Y, K
colourants), it is ideal that each colourant be printed in a pure form isolated from other colourants.
Colourant interactions can produce catalytic fading effects, whereby a primary colourant in a multi-
colourant patch will fade at a different rate than would be observed had the colourant been printed
alone. Additionally for image forming materials stability tests, secondary (mixed) colour patches (e.g.
a red patch comprised of magenta and yellow colourant) are ideally comprised of equal amounts of
two respective primary colourants, as it is known that any variance in these proportions can result
in differing rates of catalytic change. In the image forming materials stability test, “test ready” target
prints shall be produced after careful manipulation of the digital test file colour code values so that pure
printer colourant primaries and correctly proportioned printer colourant secondaries are produced in
the target print for each of the selected optical densities. Evaluation of preliminary printer assessment
prints, using, for example drop count measurements and high resolution inspection, can be useful
to determine the colour code values that produce pure (or closest to pure) colourant primaries and
correctly proportioned colourant secondaries through a given system (see Annex D). Target print
generation can also include such steps as selectively removing and replacing ink cartridges or tanks,
cutting and splicing the thermal donor, etc., to achieve a desired effect in isolating specific colourants.
The image forming materials stability test requires target prints with selected optical densities in:
a) neutral patches containing equal proportions of the printer primary colourants cyan, magenta, and
yellow;
b) patches containing isolated primary (pure) printer colourants (e.g. pure cyan, magenta, yellow and
black colourants);
c) patches containing isolated secondary (two equally proportioned primary colourants) printer
colours (e.g. red, green and blue colour patches, each comprised of equal proportions of two printer
primary colourants).
As far as is achievable in the printing system under test, isolated C, M, Y, K colourant primaries shall be
tested. As far as is achievable in the printing system under test, secondaries of R, G, B, each comprised of
equal parts of two colourant primaries, shall be tested. The colourant proportion is required, whereas
exact colour hue and colourfulness are not. Additional primary and secondary colourant patches (e.g.
red and green primaries and their associated secondaries) can be tested as needed to address specific
system capabilities, understanding that these capabilities may or may not apply to all or any other
printing systems (see Annex D).
5.4.2 Adapting the digital file for an image forming materials stability test — RGB printers
The RGB image forming materials stability test digital file shall be encoded in sRGB as defined in
IEC 61966-2-1 and saved in the tiff format with the sRGB ICC profile embedded.
NOTE Even though sRGB is a standard, the ICC profiles for sRGB can differ. Retaining the ICC profile with the
file contributes to test repeatability.
The image content shall be encoded in sRGB as defined in IEC 61966-2-1. The RGB printer case presents
challenges for the image forming materials stability test due to the lack of direct control over the printer
colourants. Adapt and evaluate the digital test file and the resulting assessment print using the printing
system configuration that provides the most direct colour matching control. With an sRGB encoding,
neutrals are typically encoded with R = G = B equal value codes. In certain cases, the printer driver
software may provide an option to assign such neutral values to the black ink. If such a single colourant
black can be obtained, then including additional selected density patches for that case is recommended
(see Annex D).
5.4.3 Adapting the digital file for an image forming materials stability test — CMYK printers
The CMYK image forming materials stability test digital file shall be encoded in device CMYK and saved
in the tiff format with the device CMYK ICC profile embedded, if available.
NOTE Take care to associate the CMYK digital test file with the printing system configuration it is tuned for,
e.g. using a coded filename, storing it with an associated metadata file.
The image content shall be encoded in “device CMYK”. The CMYK digital test file shall include patches of
minimum density (“paper white”), and patches planned to produce the selected optical densities using
the cyan, magenta, yellow and black printer primary colourants, from patch code values with only non-
zero C, M, Y, and K, respectively. In addition, the CMYK digital test file shall include patches planned to
produce the selected optical densities in red, green and blue secondary printer colours, from patch code
values with equal M and Y (zero C), equal C and Y (zero M), and equal C and M (zero Y), respectively.
Finally, the CMYK digital test file shall include patches planned to produce the desired optical densities
in composite neutral printer colour, from patch code values with equal C, M and Y.
5.5 Target print uniformity
Typical digital printing systems exhibit print non-uniformities (in-page and page-to-page) that can
affect density measurements. Digital printing systems also differ in the availability of printer process
controls that can be used to compensate for these non-uniformities. As a result, in a best case scenario,
individual patch densities can be predicted within some tolerance limits of a selected density value, but
cannot be ensured to match exactly to a selected density value, even when patch code values are tuned
for the particular printer.
The impact of these non-uniformities and control variabilities shall be minimized through target layout
design and adaptation to the particular system under test. Replicate prints can be printed and duplicate
patches can be included within a single target print page as necessary to obtain target prints that satisfy
the selected optical density requirements. Statistical analysis of the print non-uniformity characteristics
of the printing system under test should be conducted to determine the number of replicate prints and
number of duplicate patches to use.
At least two replicate prints are required. Replicates shall be positioned for testing in different regions
of the test chamber volume. Refer to Annex E for guidance in determining a measurement plan to limit
measurement error.
Many modern imaging systems now employ multiple density inks (i.e. light cyan and dark cyan) with
the result that such printing systems may or may not utilize the same colourant for each density.
Furthermore, the light and dark inks may be printed singularly or combined in various proportions to
achieve a specified density. For such printing systems, monitoring multiple densities throughout each
colour tone scale is recommended so that the stability of each colourant can be evaluated as they occur
in various combinations. The image print stability test is particularly applicable to evaluating such
printing systems.
5.6 Test chamber condition uniformity
Locally varying environmental conditions in a given test, due to patch position within a target print
or due to target holder position within a chamber, e.g. the amount of light falling on a patch in a light
stability test, can result in different OD changes in patches that are initially identical.
8 © ISO 2014 – All rights reserved

When noticeable effects are determined due to such locally varying conditions, it is recommended to
position the two or more replicate prints to be oriented differently in the test chamber and average
the raw measurements of each two or more duplicate patches in the replicates. The averages of the
measurements of the replicas shall be used as single measurements for the successive computations of
test results.
NOTE 1 Such test chamber non-uniformity effects become noticeable when measurement differences between
replicates change after testing by an amount that is greater than the expected ± variation of the measurement
instrument when measuring identical patches.
NOTE 2 Duplicate patches are patches that were printed with the same starting code values, either in replicate
prints or in redundant print areas in one target print.
NOTE 3 In addition to the use of duplicate patches, with certain chamber configurations, periodic sample
repositioning in the test chamber during an accelerated ageing test can be useful to compensate for test chamber
non-uniformity.
6 Generating the target prints
6.1 Digital print preparation
If the printing system under test cannot accept tiff image files for printing, convert the digital test
file (designed and saved as a tiff file) to the highest quality (e.g. least compressed) file format that the
printing system can accept just prior to printing. Ensure that the required patch size and patch spacing
is maintained in the converted printable file. Retain the original tiff format digital test file for future
testing.
NOTE Lossy compressed files further degrade when they are opened and closed successively in imaging
applications. For this reason, the digital test file creation and editing process uses the uncompressed tiff image,
with conversion to the lossy compressed format only as required for printing.
6.2 Source preparation for conventional silver gelatine photographic materials
Conventional silver gelatine photographic materials can be tested using the image print stability test
approach. Exposures can be controlled to produce desired print density values. Specific proportions of
colourants cannot be directly controlled.
Sensitometrically-exposed specimens designed to achieve the selected optical densities in the target
prints shall be processed using the processing system of primary interest and in accordance with the
manufacturer’s recommendations.
Processing chemicals and procedures can have a significant effect on the dark-keeping and light-keeping
stability of conventional silver gelatine photographic materials. For example, a chromogenic colour
negative print paper processed in a “washless” or “non-plumbed” system with a stabilizer rinse bath
instead of a water wash may have stability characteristics that are different from the same colour paper
processed in chemicals requiring a final water wash or using a final water wash. Therefore, the specific
processing chemicals and procedure shall be reported, along with the name of the colour product in any
reference to the test results.
Stability data obtained from a colour material processed in certain processing chemicals shall not be
assigned as belonging to colour material processed in different chemicals, or using a different processing
procedure. Likewise, data obtained from colour materials that have been subjected to post-processing
treatments (e.g. application of lacquers, plastic laminates, or retouching colours) shall not be assigned as
belonging to colour material that has not been similarly treated, and vice versa.
6.3 Configuring the printing system and generating the target prints
When printing the image forming materials stability test target, target prints shall be produced
using driver and printer settings that are appropriate for photo printing. The printer manufacturer
recommended print mode for photo printing shall be used with each printer. When multiple print mode
options are available for use with the selected photo paper, the print mode selection used shall be
included in the test report.
If the ink and substrate under test are not an OEM combination, then the closest matching media
setup provided in the driver and printer settings (e.g. “generic glossy photo paper”) shall be chosen.
As appropriate in the typical use of the printing system, ICC profiles provided by the printing system
manufacturer for the test paper and test print conditions may be used in generating image print stability
target prints. In such a case using ICC profiles, do not turn off colour management when initiating the
print.
When printing the image forming materials stability target, target prints may be produced using driver
and printer settings that afford the test operator the required control over colourant proportions.
In the digital printing case, the printer manufacturer recommended driver and printer settings for
photo printing shall be used with each printer. When multiple photo print options for resolution, print
speed, and other settings are available, the values used for each setting shall be recorded.
If the printing system requires image pre-scaling, then pre-scale the image using nearest neighbour
interpolation to the closest available printer resolution.
In accordance with the measurement plan determined during test preparation (see Annex E), necessary
replicate prints shall be printed within the closest possible time proximity.
NOTE 1 The printing system configuration should match the exact conditions that were in place when printer
assessment targets were printed, if the digital test file was adapted (patch selection in the case of an image print
stability test or patch selection and adjustment in the case of an image forming materials stability test) using a
print assessment process.
Photographic material shall be printed in accordance with the manufacturer’s recommendations.
Manufacturer’s requirements regarding colourant and print media storage and pre-conditioning and
print device operating environment shall be followed.
The specific printing system configuration used to generate the target print, as far as it can be determined
by the test operator, shall be reported with the test results. The digital test file, as used to generate
the digital target prints, shall be included in the test report, and the measurement plan (e.g. single or
bracketing patch measurements, use of duplicate patch pairs, and number of replicate prints) shall be
described.
Image print stability test results shall be documented with respect to the complete printing system:
host system identification and settings, printer driver version and driver settings, associated image
processing software, colour management software and settings, print engine, hardware configuration,
colourant set, processing chemistry, and media.
2)
NOTE 2 Software ima
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