ISO/IEC 22592-1:2024

International
Standard
ISO/IEC 22592-1
First edition
Office equipment — Print quality
2024-01
measurement methods for colour
prints —
Part 1:
Image quality measurement
methods
Reference number
© ISO/IEC 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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© ISO/IEC 2024 – All rights reserved
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Test charts .3
4.1 General .3
4.2 Test chart for colour reproduction and variations in colour reproduction .3
4.3 Test chart for show-through variations .5
4.4 Test chart for line quality, graininess and mottle, and those variations .6
5 Print preparation procedures .7
5.1 Printing environment .7
5.2 Printing materials .7
5.3 Printer settings .7
5.4 Printing operation .8
5.5 Conditioning the prints after printing.8
6 Measurement conditions .8
6.1 Measurement environmental condition .8
6.2 Colour measurement .9
6.3 Measurement of line quality, graininess and mottle .9
7 Measurement procedures and analysis of measured results . 9
7.1 General .9
7.2 Colour reproductions and those variations .10
7.2.1 Metric for colour reproduction and those variations .10
7.2.2 Colour reproduction range .10
7.2.3 Within-page variations for colour reproduction .11
7.2.4 Side-to-side variations for colour reproduction .11
7.2.5 Sheet-to-sheet variations for colour reproduction .11
7.2.6 Show-through variations for colour reproduction . 12
7.3 Line quality . 12
7.3.1 Line quality measurements . 12
7.3.2 Overall line quality . 12
7.3.3 Side-to-side variations for line quality . 12
7.3.4 Sheet-to-sheet variations for line quality . 12
7.4 Graininess and mottle . 13
7.4.1 Graininess and mottle measurements . 13
7.4.2 Overall quality for graininess and mottle . 13
7.4.3 Side-to-side variations for graininess and mottle . 13
7.4.4 Sheet-to-sheet variations for graininess and mottle. 13
8 Reporting .13
8.1 General requirements for reporting . 13
8.2 Reporting items . 13
Annex A (informative) Example of colour measurement test results .15
Annex B (informative) Correlation between colour reproduction range in ΔE and in volume .21
Bibliography .23

© ISO/IEC 2024 – All rights reserved
iii
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical activity.
ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations,
governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.
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 document 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 or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not
received notice of (a) patent(s) which may be required to implement this document. However, implementers
are cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held
responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 28, Office equipment.
A list of all parts in the ISO/IEC 22592 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.

© ISO/IEC 2024 – All rights reserved
iv
Introduction
There are several standard measurement methods to evaluate image quality attributes of printed images
formed by office equipment, i.e. colour reproductions, line reproductions, image structures of sharpness and
graininess, gloss properties. Included are ISO/IEC 19799, ISO/IEC 24790 and ISO/IEC 29112. ISO/IEC 24790
specifies the measurement methods for large area density uniformity of graininess, mottle and banding,
as well as line qualities. ISO/IEC 29112 specifies the methods for measuring sharpness attributes of edge
blurriness and raggedness, special frequency response, etc. ISO/IEC 19799 specifies the methods for gloss
uniformity. By utilizing these documents, users can obtain consistent test results when they comply with
the protocols specified in the documents.
There are no standard methods to measure colour reproduction consistencies and geometrical accuracies
in consecutive printing, and image stabilities in typical use case of print images formed by office equipment
and used in office environments. In the current state, each printer distributer and its user can provide test
results for those attributes measured by its own test methods and procedures, which are often convenient
for its product, resulting in misleading customers in the selection of a printing system suitable for their
use cases. The ISO/IEC 22592 series can provide standard methods and procedures for these print image
attributes: ISO/IEC 22592-1 for colour consistency, ISO/IEC 22592-2 for geometrical accuracies and
1)
ISO/IEC 22592-3 for image stabilities. By using these International Standards, consistent and comparable
test results suitable for typical use cases of office prints can be obtained independent of data providers.
This document specifies measurement methods that quantitatively evaluate image quality attributes and
test charts to measure the attributes as well as the variations in measured attributes in colour prints formed
under the environment and stress assuming general office use case. The attributes for duplex colour print
sets are within the scope as most of office documents are currently printed in duplex print sets comprising
several sheets printed with colour images on both surfaces of substrates.
The measurement methods described in this document are used to access image qualities of a print
set formed by a printing system on a substrate. When test results are compared among various printing
systems, it is essential to use the same product of substrates and set equivalent printing conditions under
default printer settings among the printing systems.
Electrophotography, thermal inkjet, or piezoelectric inkjet technologies are commonly used to form such
prints. The purpose of this document is to provide objective measurement methods for image quality
attributes of duplex colour print sets.
This document prescribes the following:
— test charts for the measurements which specify colour codes and locations in page to be measured;
— measurement method for colour reproduction range;
— measurement methods for colour variations, including variation by location within a page (within-page
variation), variation between front and back side (side-to-side variation), variation among the sheets in
the same print set (sheet-to-sheet variation) and variations depending on the colours printed on its back
side (show-through variation);
— measurement methods for the attributes of line quality, graininess and mottle based on ISO/IEC 24790
and variations (side-to-side, sheet-to-sheet variations, etc.) in attributes.
The above methods relating to image quality variations are mainly designed to quantify the variations in
duplex print sets. On the other hand, it is convenient for users to evaluate simplex print sets, comprising
several sheets which are printed with colour images on one surface of a substrate and no image on the other
surface, by using the same methods for duplex print sets. Therefore, some attributes for variations, such as
colour variations “within a printed image”, “sheet-to-sheet variations”, can also be applicable for a simplex
print set.
Measurement methods for gloss and its variations are out of the scope of this document, and have already
been specified in ISO/IEC 19799.
1) Under preparation. Stage at the time of publication: ISO/IEC DIS 22592-3:2023.

© ISO/IEC 2024 – All rights reserved
v
In this document colour codes for the test charts are defined in sRGB colour space as specified in IEC 61966-2-1
as is common in office documents colour measurements are based on CIELAB specified in ISO/CIE 11664-4.

© ISO/IEC 2024 – All rights reserved
vi
International Standard ISO/IEC 22592-1:2024(en)
Office equipment — Print quality measurement methods for
colour prints —
Part 1:
Image quality measurement methods
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of this document. Users should therefore consider printing with
a colour printer.
1 Scope
This document specifies test methods as well as test charts to measure the image quality attributes and
those variations in colour prints typically used in office environment. Included are digital colour prints
formed by using a multifunction or single function printer. Printers supporting a maximum paper size of A4
or larger are suitable for the measurements using the test charts defined in this document.
The image quality attributes included are colour reproduction, line quality, graininess and mottle.
The sources of variation considered are locations in a page (within-page variation), printed side in a sheet
(side-to-side variation), printed order of the sheet (sheet-to-sheet variation) and colours printed on the back
side of evaluated patch (show-through variation).
A duplex print set, comprising several sheets which are printed by multifunction or single function printer
with colour images on both surfaces of a substrate, is a main application of the test methods to measure
image quality variations in the set. Variations, such as within-page variation and sheet-to-sheet variation,
are also applicable for a simplex print set comprising several sheets which are printed colour images on one
surface of a substrate and no image on the other surface.
Both duplex and simplex printers are applicable to form a print set. When image qualities of duplex prints
are measured, duplex printers which are capable to print images on both sides of substrate automatically
are applicable to form duplex prints. However, simplex printers which require a manual arrangement
of substrates between the front side and back side printing to form duplex prints are out of scope of this
document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts images
ISO/IEC 24790, Information technology — Office equipment — Measurement of image quality attributes for
hardcopy output — Monochrome text and graphic images
ISO/CIE 11664-4, Colorimetry — Part 4: CIE 1976 L*a*b* colour space
ISO/CIE 11664-6, Colorimetry — Part 6: CIEDE2000 colour-difference formula
IEC 61966-2-1, Multimedia systems and equipment — Colour measurement and management — Part 2-1: Colour
management — Default RGB colour space — sRGB

© ISO/IEC 2024 – All rights reserved
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 24790 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
back side
print side (3.10) corresponding to an even page of input data
3.2
blurriness
appearance of being hazy or indistinct in outline, a noticeable transition of darkness from line element to
background substrate whose intended transition width is zero (i.e. ideally sharp)
[SOURCE: ISO/IEC 24790:2017, 3.5]
3.3
character darkness
appearance of blackness of a line or character image
[SOURCE: ISO/IEC 24790:2017, 3.7]
3.4
colour reproduction range
index corresponding to colour reproduction property of a print taking only input colours of C, M, Y, K and W
(blanc area) into account
3.5
front side
print side (3.10) corresponding to an odd page of input data
3.6
graininess
appearance of unintended microscopic, but visible, aperiodic fluctuations of lightness
Note 1 to entry: Microscopic means: variations with spatial frequencies greater than about 0,4 cy/mm.
[SOURCE: ISO/IEC 24790:2017, 3.13]
3.7
line width
average stroke width, where the stroke width is measured from edge to edge along a line normal to the
centre line of the image element
[SOURCE: ISO/IEC 24790:2017, 3.23]
3.8
mottle
measure of the appearance of unintended, aperiodic macroscopic fluctuations of lightness
Note 1 to entry: Macroscopic means: variations with spatial frequencies less than about 0,4 cy/mm.
[SOURCE: ISO/IEC 24790:2017, 3.26]
3.9
print set
set of sheets printed in a print operation

© ISO/IEC 2024 – All rights reserved
3.10
print side
one of the duplex print surfaces, either front side (3.5) or back side (3.1)
3.11
raggedness
appearance of geometric distortion of an edge from its ideal position
Note 1 to entry: An ideal edge should be absolutely straight along the length of the line.
Note 2 to entry: A ragged edge appears rough or wavy rather than smooth or straight.
[SOURCE: ISO/IEC 24790:2017, 3.29]
3.12
sheet-to-sheet variation
change in an attribute at the same input data on the same print side (3.10), either the front side (3.5) or back
side (3.1), within a print set (3.9)
3.13
show-through variation
change in the colour at the same input colour code value caused by the colour image printed on the back side
(3.1) of the same sheet
3.14
side-to-side variation
change in an attribute at the same input data in the same sheet between front and back side (3.1)
3.15
within-page variation
change in an attribute at the same input data by location within a page
4 Test charts
4.1 General
There are three test charts defined in this document. The first is illustrated in Figure 1 for the measurements
of colour reproduction, and within-page, side-to-side, sheet-to-sheet variations in colour reproduction. The
second is illustrated in Figure 2 for the measurement of show-through variations. The third is illustrated in
Figure 3 for the measurement of line quality, graininess and mottle, and those variations. The colour codes
of the test charts shall be encoded in standard sRGB, as defined in IEC 61966-2-1, which is commonly used in
office documents.
Those test charts are prepared in the PDF file format and can be downloaded from:
https:// standards .iso .org/ iso -iec/ 22592/ -1/ ed -1/ en/ .
4.2 Test chart for colour reproduction and variations in colour reproduction
The outline of the test chart is described in Figure 1. The test chart is composed of the two images in raster
graphics. The first page is used to print an image for front side and the second for back side. The size is A4
for both sides.
Total of nine components, each comprising the 16 patches of cyan (C), magenta (M), yellow (Y), black (K),
red (R), green (G), blue (B), white (W), light cyan (LC), light magenta (LM), light yellow (LY), light grey (LK),
light red (LR), light green (LG), light blue (LB) and mid grey (MK), are arranged in a print side to evaluate
within-page variations. Each component for the back side is shifted by half pitch towards the long-edge
direction from the corresponding component for the front side to measure patch colour value without the
influence of printed image on its back side.

© ISO/IEC 2024 – All rights reserved
The sRGB colour codes of those patches are described in Table 1. The colour codes of C, M, Y, K, R, G, B and W
patches outline the edge of intended colour reproduction range in the sRGB colour space. Each colour code
for the light colour patches of LC, LM, LY, LK, LR, LG and LB is located at 30 % highlight of the corresponding
saturated patch (colour code = 178). Colour code for MK is located midpoint between W and K patches.
Key
e
A frontside Component E.
f
B backside Component F.
a g
Component A. Component G.
b h
Component B. Component H.
c i
Component C. Component I.
d
Component D.
Figure 1 — Illustrated test chart for colour reproduction and its variations
Table 1 — sRGB colour codes of colour patches of test chart for colour reproduction and its
variations
Colour
C M Y K R G B W LC LM LY LK LR LG LB MK
code
R 0 255 255 0 255 0 0 255 178 255 255 178 255 178 178 128
G 255 0 255 0 0 255 0 255 255 178 255 178 178 255 178 128
B 255 255 0 0 0 0 255 255 255 255 178 178 178 178 255 128

© ISO/IEC 2024 – All rights reserved
4.3 Test chart for show-through variations
The outline of the test chart is described in Figure 2. The test chart is composed of the two images in raster
graphics. The first page is used to print an image for the front side and the second for the back side. The size
is A4 for both sides.
A total of 16 components of C, M, Y, K, R, G, B, W, LC, LM, LY, LK, LR, LG, LB and MK, each comprising the
9 patches of the same colour code, are arranged at the centre of the front side. Each component has the 9
different saturated colour patches of C, M, Y, R, G, B, W, K and W printed on its back side to measure colour
values dependence on the back-side colours.
The sRGB colour codes of those patches are the same as those in 4.2 as described in Table 1.
Key
h
A frontside Component H.
i
B backside Component I.
a j
Component A. Component J.
b k
Component B. Component K.
c l
Component C. Component L.
d m
Component D. Component M.
e n
Component E. Component N.
f o
Component F. Component O.
g p
Component G. Component P.
Figure 2 — Illustrated test chart for show-through variations

© ISO/IEC 2024 – All rights reserved
4.4 Test chart for line quality, graininess and mottle, and those variations
The outline of the test chart is described in Figure 3. The size of each page is A4.
The same four image patterns are arranged in page 1 and page 4. Each image pattern comprises nine halftone
patches of shadow, mid and highlight for C, M and K, and three set of line patterns of different line angles of
vertical, horizontal and diagonal, each composed of three different line widths of 0,12 pt, 0,24 pt and 0,36 pt
(equivalent to 1 dot, 2 dots and 3 dots at 600 dpi), corresponding to around 42,3 µm, 84, 7 µm and 127,0 µm,
based on the definition of 1 inch = 25,4 mm, for three input colours of C, M and K. Blank pages are inserted
for page 3 and page 4 to eliminate the influence of show through.
Each patch size shall be equal to or larger than 25 mm × 25 mm. The length of each line image shall be equal
to or longer than 20 mm.
The sRGB colour codes of those patches and line images are described in Table 2.
Each element in the first and fourth pages shall be vector graphics.
The test chart is encoded to PDF under the following conditions:
— no colour and tone correction,
— no reduction or enlargement in printed size,
— no image compression,
— resolution higher than 2 400 dpi of a pitch of around 10,6 µm.
Key
A page 1 (front side of odd sheet)
B page 2 (back side of odd sheet)
C page 3 (front side of even sheet)
D page 4 (front side of even sheet)
Figure 3 — Illustrated test chart set for line quality, graininess and mottle, and those variations

© ISO/IEC 2024 – All rights reserved
Table 2 — Area coverage of colour patches and line images of test chart for line quality, graininess
and mottle and its variations
Shadow Mid Highlight Line object
Colour
code
C M K C M K C M K C M K
R 51 255 51 127 255 127 192 255 192 0 255 0
G 255 51 51 255 127 127 255 192 192 255 0 0
B 255 255 51 255 255 127 255 255 192 255 255 0
5 Print preparation procedures
5.1 Printing environment
Printers shall be installed in an environment having a temperature of (23 ± 5) °C, with a relative humidity
(RH) of (50 ± 10) % at least 2 h prior to print operations and the print operations shall be completed in the
same environment. The paper to be used shall be placed in a paper tray when the printers are installed.
Prior to the installation of printers, additional seasoning of papers under the same environmental conditions
described above for more than 24 h is recommended to stabilize the water content of the papers which often
affects image qualities of prints.
If a printer has not been used for a long period or if the environmental difference between storage and
evaluation area is large, it is recommended to install it 12 h prior to the test and to print 10 or more sheets
for warm up before the test.
5.2 Printing materials
An A4 sized plain paper shall be used to correspond well with a typical usage case of office prints. Coated
papers for ink jet or lithography can be used for a specific usage case with a rational explanation in reporting.
2 2
The grammage of the paper shall be from 60 g/m to 90 g/m . The other grammage for paper can be used
for a specific usage case with a rational explanation in reporting. The name, grammage and supplier of the
paper shall be reported.
The opacity of substrates specified in ISO 2471 should also be reported.
Toner or ink materials recommended by the manufacturer of the printer to be tested shall be used. The other
materials provided by the suppliers other than the original manufacturer of a printer for measurements can
be used as long as the product name and supplier are included in the report.
The other printing materials, such as photoreceptors in electrophotographic printer, or the print head in an
ink jet printer, shall be in accordance with the recommendations of the printer's manufacturer. The printing
materials provided by the suppliers other than the original manufacturer of a printer for measurements can
be used as long as the product name and supplier are included in the report.
5.3 Printer settings
Colour and paper settings in the driver and printer usually control mass density of colourants in high area
coverage input images as well as halftone dot structures in mid-tone and highlight input images. Therefore,
the former affects the colour reproduction range and the show through, and the latter affects graininess and
mottle at the corresponding input images.
When printing a test chart, prints shall be produced using driver and printer settings that are appropriate
for a typical usage case in office. Default settings for the substrate subjected to evaluation, which correspond
to initial settings when a printer shipped out are recommended to be used. When performances of printing
systems are compared, the default settings for each printing system shall be selected. The driver and printer
settings used shall be described in the test report.
No reduction or enlargement in printed size shall be made. Modifications in colour and tone reproduction,
sharpness enhancement, or noise reduction in the printer settings shall not be used. The printing mode by

© ISO/IEC 2024 – All rights reserved
which an input image is printed at the centre of the substrate shall be selected. No binding margin shall be
arranged.
NOTE It is important to check if the size and position in a substrate are consistent. In some application viewers
or printer settings for PDF files, settings related to size modification or printed position in a substrate at the previous
print operation remain unchanged.
For the printers of the maximum applicable paper size of A3 or larger, the feed direction parallel to the short
edge of A4 paper shall be selected and the feed direction perpendicular to the short edge of A4 paper can
optionally be selected. In the printers of the maximum applicable paper size of A4, the feed direction shall be
in accordance with printer setting for A4 size paper. Long edge binding shall be selected in duplex printing.
5.4 Printing operation
Printing can be initiated under any operational mode defined in Reference [7], i.e. ‘On Mode’(‘Active State’,
‘Ready State’), ‘Off Mode’ or ‘Sleep Mode’. In order to evaluate overall performance of a printing system, it
is recommended to carry out the tests under multiple operational modes. When performances of printing
systems are compared, the same operational mode shall be used. The operational mode selected shall be
included in the report.
Ten sheets of a duplex print shall be printed continuously by using the test chart described in 4.2 for the
measurement of colour reproduction and variations in colour reproduction. When a simplex print is
subjected to be measured, ten sheets of a simplex print shall be printed continuously by using only the front
side image in the test chart described in 4.2 for the measurement of colour reproduction and variations in
colour reproduction.
A sheet of a duplex print shall be printed by using the test chart described in 4.3 for the measurement of
show-through variations.
Ten print sets, each set comprising two sheets of duplex prints shall be printed continuously by using the test
chart described in 4.4 for the measurement of line quality, graininess and mottle, and those variations. When
a simplex print is subjected to be measured, ten print sheets of simplex prints shall be printed continuously
by using page 1 in the test chart described in 4.4 for the measurement of line quality, graininess and mottle,
and those variations.
It is recommended to prepare duplicated print sets for each measurement for backup and to carry out
measurements with duplicated print sets for measurement noise reduction.
5.5 Conditioning the prints after printing
Prior to measurements, aqueous inkjet prints, or prints of any type that require curing/stabilization/
dry-down, shall be conditioned in a controlled environment for at least 24 h after printing. Considering
mitigating colour changes caused by the exposure of environmental factors, such as light, high temperature
and humidity during the conditioning, the controlled environment shall be the relative humidity between
30 % to 70 % and the temperature between 15 °C to 28 °C, with ambient illuminance on the print surface
less than 1 000 lx.
6 Measurement conditions
6.1 Measurement environmental condition
All measurements in this document shall be completed in a controlled environment of relative humidity
between 30 % to 70 % and temperature between 15 °C to 28 °C. It is recommended to complete a series of
measurements continuously in a short duration to prevent the change in colour because of environmental
factors.
© ISO/IEC 2024 – All rights reserved
6.2 Colour measurement
The CIELAB colour space values shall be obtained from measurements using ISO 13655 measurement
conditions.
Conforming to ISO 13655, calculated tristimulus values and corresponding CIELAB values of the colorimetry
shall be computed using CIE illuminant D50 and the CIE 1931 standard colorimetric observer (often referred
to as the 2° standard observer). Self-backing or white-backing is recommended with respect to a typical
office document composed of several sheets of a low area coverage print. The same illuminant condition,
either M0, M1 or M2 shall be maintained for a series of colour measurements. It is recommended to apply M2,
which is insensitive to the variation of optical brightener in papers when the colour variations originated by
the performance of print equipment are evaluated.
Measurement instruments shall be calibrated in accordance with manufacturer’s instructions. The same
measurement instrument is recommended to be used for all of the same kind of measurements.
6.3 Measurement of line quality, graininess and mottle
The measurement methods described in ISO/IEC 24790 shall be used for line quality, graininess and mottle
measurements. Line quality includes line width, line blurriness, line raggedness and line darkness. A scanner
complying with the requirements in ISO/IEC 24790 shall be used to capture printed objects. Measurement
procedures in detail shall be in accordance with those in ISO/IEC 24790.
7 Measurement procedures and analysis of measured results
7.1 General
This clause describes the measurement procedures and analysis of the measurement results. The overview
of the measurements is described below. There are three groups of measurements: colour reproductions
and those variations, line quality and graininess and mottle.
The outline of measurements is as following:
Group of attribute Attribute Subclause
Colour reproductions and those variations 7.2
Metric for colour reproduction and those variations 7.2.1
Colour reproduction range 7.2.2
Within-page variations for colour reproduction 7.2.3
Side-to-side variations for colour reproduction 7.2.4
Sheet-to-sheet variations for colour reproduction 7.2.5
Show-through variations for colour reproduction 7.2.6
Line quality 7.3
Line-quality measurements 7.3.1
Overall line quality 7.3.2
Side-to-side variations for line quality 7.3.3
Sheet-to-sheet variations for line quality 7.3.4

© ISO/IEC 2024 – All rights reserved
Graininess and mottle 7.4
Graininess and mottle measurements 7.4.1
Overall quality for graininess and mottle 7.4.2
Side-to-side variations for graininess and mottle 7.4.3
Sheet-to-sheet variations for graininess and mottle 7.4.4
NOTE 1 Those attributes can be evaluated quantitatively using the measurement methods in 7.2. However, the
correlations between indexes and subjective impressions of the attributes included in this document has not been
demonstrated.
NOTE 2 Examples of test results are shown in Annex A.
7.2 Colour reproductions and those variations
7.2.1 Metric for colour reproduction and those variations
Colour reproduction properties shall be evaluated in terms of CIELAB L*, a* and b* values defined in
*
ISO/CIE 11664-4. Variations in the colour reproductions shall be evaluated in terms of ΔE (delta E 76) as
ab
*
defined in ISO/CIE 11664-4 or ΔE (delta E 00) as defined in ISO/CIE 11664-6.
* * *
Colour variations can be specified by three kinds of indexes: the average ΔE , worst ΔE and 95 % tile in ΔE .
It is recommended to use 95 % tile which shows conservative values for users and eliminates the effect of
accidental errors in measurements. In the case 95 % tile is taken, C = 1 in the linear interpolation between
closest ranks method described in ISO/TS 15311-1:2020, Annex C in which the value for 95 % tile is linearly
interpolated from the value for the closest rank over 95th and that under 95th, is recommended to be
adopted to estimate the value when 0,95 is not equal to the multiple number of 1/(n-1), in which “n” is the
number of the data to estimate the value for 95 % tile.
NOTE The PERCENTILE.INC function in Microsoft® Excel® corresponds to 95 % tile at C = 1 in the linear
interpolation between closest ranks.
7.2.2 Colour reproduction range
Colour reproduction range, R shall be evaluated in terms of the average L*a*b* colour coordinates for the
cr
input data of C, M, Y, R, G, B, W and K patches in 4.2. The average colour coordinate for each colour shall be
calculated by averaging the colour coordinates of 180 patches for the colour within a print set, comprising
10 sheets of front side and back side prints each includes 9 patches for the colour. Optionally, the average
colour coordinate for each colour can be the average colour coordinate for each colour patch of the front side
and back-side prints of the fifth sheet to reduce the burden for the colour measurements with a comment in
its report that ‘Colour reproduction range is calculated only for the fifth sheet of the print set and sheet-to-
sheet variations of colour reproduction range are not taken into account’.
NOTE 1 Colour reproduction range is affected by random substrate variation which changes not only the colour of
the white background but also the colour of the patches due to the variation in colourant penetration and spreading
with the surface and inner properties of substrate.
Colour reproduction range can be evaluated in terms of the index obtained by summing the total of 12 colour
*
difference values in the CIELAB colour space, i.e. the colour difference values in ΔE between the average
ab
colour coordinate of W and that of each colour of C, M, Y, R, G and B, and between that of K and that of each
colour of C, M, Y, R, G and B.
*
The colour difference value in ΔE can be calculated by Formula (1):
ab
** 22** ** 2
ΔE* =−()LL +−()aa +−()bb (1)
ab ij ij ij
where i ∈ {C, M, Y, R, G, B}, and j ∈ {W, K}.

© ISO/IEC 2024 – All rights reserved
Consequently, the metric for the range corresponding to colour reproduction range can be calculated by
Formula (2):
** 22** ** 2
RL =−()La+−()ab+−()b (2)
cr ∑ ∑ ij ij ij
i j
where i ∈ {C, M, Y, R, G, B}, and j ∈ {W, K}.
NOTE 2 Formula (2) assumes additive mixture in colour reproduction, which is applicable only in a linear
system, such as display devices in the sRGB colour space. However, the assumption is not true due to no linearity
in colour mixture at the CIELAB colour space as well as the subtractive mixture caused by the duplicated colourant
layer structure in common printing devices. The formula is beneficial to estimate a schematic overview of colour
reproduction range of a printing system. An example showing the correlation between the colour reproduction range
and volume of tetrahedral comprising C, M, Y, R, G, B, W, and K is shown in Annex B.
7.2.3 Within-page variations for colour reproduction
For each of the 16 input colours in Figure 1 of C, M, Y, K, R, G, B, W, LY, LM, LC, LK, LR, LG, LB and MK printed
on each page, the worst colour difference, “Wst ΔE* for a page” in terms of ΔE* (delta E 76) or ΔE* (delta
ab 00
E 00) of all the combinations of two patches of the 9 components printed on the different locations in the
page shall be calculated.
NOTE There are total 576 (= 9C × 16 = (9 × 8)/(2 × 1) ×16) ΔE* to be calculated for the 2-patches-combinations
of 9 components for 16 input colours for a page. Within-page variation for each colour shall be calculated in terms of
average or 95 % tile value of “Wst ΔE* for a page” among the 20 pages (10 sheets ×2 sides). Optionally, within-page
variation for each colour can be obtained by averaging “Wst ΔE* for a page” for each colour patch of the front-side and
back-side prints of the fifth sheet to reduce the burden for the colour measurements with a comment in its report that
'within-page variation for each colour in this report is calculated only for the fifth sheet of the print set and Sheet-to-
sheet variation are not taken into account'.
7.2.4 Side-to-side variations for colour reproduction
For each of the 16 input colours in Figure 1 of C, M, Y, K, R, G, B, W, LY, LM, LC, LK, LR, LG, LB and MK printed
on all the sheets, “side-to-side ΔE*”, the colour difference in terms of ΔE* (delta E 76) or ΔE* (delta E 00)
ab 00
between the average CIELAB colour coordinate of the 9 components on the front side and that on the back
side shall be calculated.
N
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