Information technology -- Office equipment -- Test pages and methods for measuring monochrome printer resolution

This document defines methods for the objective measurement of the print quality characteristics that contribute to the perceived resolution of reflection mode monochrome printed pages produced by digital electro-photographic printers. The measurement methods of this document are derived from several existing techniques for the assessment of an imaging system's resolution characteristics. Each of these measurement methods is intended for the engineering evaluation of a printing system's perceived resolution and is not intended to be used for purposes of advertising claims. The methods of this document are applicable only to monochrome prints produced in reflection mode by electro-photographic printing technology. This document is intended for monochrome printers utilizing PostScript®[1] interpreters capable of accepting PostScript and encapsulated PostScript (EPS) jobs. [1] PostScript® and Encapsulated PostScript® are registered trademarks for freely usable page description formats controlled and defined by Adobe Systems Incorporated. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO/IEC.

Technologies de l'information -- Équipement de bureau -- Diagrammes et méthodes pour mesurer la résolution des imprimantes monochromes

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Published
Publication Date
06-Nov-2018
Current Stage
6060 - International Standard published
Start Date
29-Oct-2018
Completion Date
07-Nov-2018
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INTERNATIONAL ISO/IEC
STANDARD 29112
First edition
2018-11
Information technology — Office
equipment — Test pages and methods
for measuring monochrome printer
resolution
Technologies de l'information — Équipement de bureau —
Diagrammes et méthodes pour mesurer la résolution des imprimantes
monochromes
Reference number
ISO/IEC 29112:2018(E)
ISO/IEC 2018
---------------------- Page: 1 ----------------------
ISO/IEC 29112:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2018 – All rights reserved
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ISO/IEC 29112:2018(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and abbreviations ............................................................................................................................................ 1

3.1 Terms and definitions ....................................................................................................................................................................... 1

3.2 Abbreviations ........................................................................................................................................................................................... 6

4 Print resolution characteristics — Methods for measurement and analysis ........................................6

4.1 Conformance requirements ......................................................................................................................................................... 6

4.1.1 General...................................................................................................................................................................................... 6

4.1.2 Test page conformance ............................................................................................................................................... 6

4.1.3 Printing process conformance ............................................................................................................................. 7

4.1.4 Scanner characteristics conformance ............................................................................................................ 7

4.1.5 Measurement method conformance ............................................................................................................... 7

4.2 Native addressability ......................................................................................................................................................................... 8

4.2.1 General...................................................................................................................................................................................... 8

4.2.2 Method for measuring native addressability .......................................................................................... 8

4.3 Effective addressability ................................................................................................................................................................10

4.3.1 General...................................................................................................................................................................................10

4.3.2 Method for measuring effective addressability ..................................................................................10

4.4 Edge blurriness and edge raggedness .............................................................................................................................12

4.4.1 General...................................................................................................................................................................................12

4.4.2 Edge blurriness ..............................................................................................................................................................12

4.4.3 Edge raggedness ...................................................................... ......................................................................................13

4.4.4 Method for measuring edge blurriness and edge raggedness ...............................................14

4.5 Spatial frequency response .......................................................................................................................................................15

4.5.1 General...................................................................................................................................................................................15

4.5.2 Printer SFR estimation from edge characteristics ...........................................................................15

4.5.3 Method for measuring printer SFR from edge characteristics ..............................................15

4.5.4 Printer SFR estimation from 1-D repeating patterns ....................................................................16

4.5.5 Method for measuring printer SFR from 1-D repeating pattern characteristics ...16

4.6 ROI size and shape variation ....................................................................................................................................................18

5 Test set-up, configurations and procedure ............................................................................................................................18

5.1 Printer set-up and configuration ..........................................................................................................................................18

5.2 Printer testing environment .....................................................................................................................................................19

5.3 Substrate ...................................................................................................................................................................................................19

5.4 Test platform connection to the printer .........................................................................................................................19

5.5 Printing process ..................................................................................................................................................................................19

5.6 Test pages .................................................................................................................................................................................................19

5.7 Sample size ..............................................................................................................................................................................................20

5.8 Set-up procedure ................................................................................................................................................................................20

5.9 Testing procedure for visual evaluation .........................................................................................................................20

5.10 Testing procedure for scanner-based measurement ..........................................................................................21

6 Presentation of results ................................................................................................................................................................................21

6.1 General ........................................................................................................................................................................................................21

6.2 Required assessment configuration documentation ..........................................................................................22

6.3 Required assessment measurement documentation .........................................................................................23

Annex A (normative) Printing process ............................................................................................................................................................25

Annex B (normative) Scanner conformance .............................................................................................................................................30

Annex C (normative) Reference measurement methods and conformance ............................................................36

© ISO/IEC 2018 – All rights reserved iii
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ISO/IEC 29112:2018(E)

Annex D (informative) Reporting ..........................................................................................................................................................................53

Annex E (informative) Usage ......................................................................................................................................................................................59

Annex F (informative) Electro-photographic system measurement method verification example 65

Bibliography .............................................................................................................................................................................................................................87

iv © ISO/IEC 2018 – All rights reserved
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ISO/IEC 29112:2018(E)
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. In the field of information technology, ISO and IEC have established a joint technical committee,

ISO/IEC JTC1.

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).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC 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 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 the following

URL: www .iso .org/iso/forward .html.

This document was prepared by Technical Committee ISO/IEC JTC1, Information technology,

Subcommittee SC 28, Office equipment.
This first edition cancels and replaces ISO/IEC TS 29112:2012.

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.
© ISO/IEC 2018 – All rights reserved v
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ISO/IEC 29112:2018(E)
Introduction

The purpose of this document is to provide a process for the objective measurement of print quality

characteristics that contribute to perceived resolution in pages printed on paper or similar opaque

materials using monochrome electro-photographic printing processes.
This document prescribes the following:

— Definitions of print quality characteristics that contribute to perceived resolution.

— Definitions of conformance methods to qualify a reflection scanner for use as a measuring device.

— A testing procedure based upon:
a) a well-documented printer and printing environment setup,
b) well-controlled printing of specified test pages, and

c) subsequent measurement of print quality characteristics using reflection scans of test pattern

elements on the printed test pages.

— Definitions of methods for measuring the contributing print quality characteristics using printed

test pattern elements of the specified test pages and analysing the resulting data to derive an

assessment of printer resolution.

— Requirements for the report of a printer resolution assessment that define the context of the

assessment and describe the results of the assessment.

Printer resolution, a quantification of the ability of a digital printing system to depict fine spatial

detail, is a perceptually complex entity with no single, simple, objective measure. Five print quality

characteristics that meaningfully contribute to resolution are described in this document. These

print quality characteristics are: native addressability, effective addressability, edge blurriness, edge

raggedness and the printing system spatial frequency response characteristic (SFR).

— Native or physical addressability refers to the imaging framework in a digital printing process,

usually a rectangular grid of printable spots, which enables depiction of fine spatial detail. Native

addressability specifies only one facet of the perceived resolution of a printing system. The common

unit for native addressability is DPI (dots per inch).

— Effective addressability is a measure of the minimum pitch by which the centre of a printed object

(e.g. line segment) can be displaced and evaluates the effects of imaged spot position modulation,

size modulation or exposure modulation.

— Edge blurriness provides an optical measure of the geometric transition width of an edge between

an unprinted substrate region and a printed solid area region.

— Edge raggedness provides an optical measure of the geometric deviations of a printed edge from a

requested straight line.

— The spatial frequency response characteristic (SFR) describes the ability of a linear imaging system

to depict fine spatial detail. This is the spatial analogue of frequency response used to characterize

sound reproduction. A common synonym of the SFR characteristic is the modulation transfer

function (MTF). The ability to depict fine spatial detail is affected by edge blurriness and edge

raggedness as well as the spot size and shape of the printer's marking technology and any adjacency

effects that can occur in the reproduction of fine detail. Two measurement methods are described

that provide estimates of the printing system's spatial frequency response including contributions

from edge blurriness, edge raggedness, spot-size, spot shape and adjacency effects.

An essential part of the development of this document was verification that the specified measurement

methods correlate well with perceived printer resolution (the ability of a digital printing system to depict

fine spatial detail) and that the measurements are reproducible across laboratories and instruments.

vi © ISO/IEC 2018 – All rights reserved
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ISO/IEC 29112:2018(E)

The steps in and results of this process to verify the utility of the measurement methods specified in

this document are presented in more detail in Annex F. The applicability of the measurement methods

specified in this document could be expanded by undertaking similar verification processes with other

printing technologies.
© ISO/IEC 2018 – All rights reserved vii
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INTERNATIONAL STANDARD ISO/IEC 29112:2018(E)
Information technology — Office equipment — Test
pages and methods for measuring monochrome printer
resolution
1 Scope

This document defines methods for the objective measurement of the print quality characteristics

that contribute to the perceived resolution of reflection mode monochrome printed pages produced

by digital electro-photographic printers. The measurement methods of this document are derived

from several existing techniques for the assessment of an imaging system's resolution characteristics.

Each of these measurement methods is intended for the engineering evaluation of a printing system's

perceived resolution and is not intended to be used for purposes of advertising claims.

The methods of this document are applicable only to monochrome prints produced in reflection mode by

electro-photographic printing technology. This document is intended for monochrome printers utilizing

PostScript® interpreters capable of accepting PostScript and encapsulated PostScript (EPS) jobs.

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 12233, Photography — Electronic still picture imaging — Resolution and spatial frequency responses

ISO 14524, Photography — Electronic still-picture cameras — Methods for measuring opto-electronic

conversion functions (OECFs)

ISO 16067-1, Photography: Spatial resolution measurements of electronic scanners for photographic

images — Part 1: Scanners for reflective media

ISO/IEC 24790, Information technology — Office equipment — Measurement of image quality attributes

for hardcopy output — Monochrome text and graphic images
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org
3.1.1
addressability
number of uniquely identifiable printable spot positions per unit distance

1) PostScript® and Encapsulated PostScript® are registered trademarks for freely usable page description

formats controlled and defined by Adobe Systems Incorporated. This information is given for the convenience of

users of this document and does not constitute an endorsement by ISO/IEC.
© ISO/IEC 2018 – All rights reserved 1
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ISO/IEC 29112:2018(E)
3.1.2
bitmap

two-dimensional rectangular matrix of values representing the pixels (3.1.21) in a printed page

3.1.3
cross-track

oriented perpendicular to the direction of print substrate motion (cross-track direction)

3.1.4
cross-track addressability

addressability (3.1.1) of the printer in the direction perpendicular to the motion of the print substrate

through the printer
3.1.6
edge blurriness

appearance of being hazy or indistinct in outline, giving a noticeable transition of density from a line

element to the background substrate whose transition width is zero for an ideally sharp edge

Note 1 to entry: The measured optical width of the transition region perpendicular to the straight edge boundary

between an unprinted substrate area and a solid printed area provides an assessment of edge blurriness.

3.1.7
edge raggedness
appearance of geometric distortion of an edge from its ideal position

Note 1 to entry: Measurement of the geometric deviations from straightness of a contour at a specific reflectance

ratio in the edge boundary region between the unprinted substrate area and the solid printed area of a requested

straight edge provides an assessment of edge raggedness.

Note 2 to entry: An ideal edge should be absolutely straight along the length of a straight line.

3.1.8
edge transition width

distance between the points of a normal edge profile (3.1.19) identified at 70 % of the edge transition

reflectance range and 10 % of that reflectance range, the region in which edge blurriness (3.1.6) is

measured

Note 1 to entry: The edge transition reflectance range is the reflectance difference between the maximum

measured reflectance factor, R , typically of the substrate, and the minimum measured reflectance factor,

max
R , typically of a region printed at a maximum printing value.
min
3.1.9
edge spread function

normalized spatial signal distribution in the scanned output of a printing system resulting from

imaging a theoretical infinitely sharp edge

Note 1 to entry: In measurement of the edge spread function, the tone-scale of the scanning system is corrected

to be linear in reflectance. See ISO 12231.
3.1.10
effective addressability

one over the minimum pitch by which the centre of a printed object can be displaced, with the constraint

that the objects compared are of constant dimension in the direction parallel to the centroid position

change direction

Note 1 to entry: The effective addressability of a printer can be greater than its native addressability. This higher

effective addressability is generally controlled algorithmically within the digital data path processing of the

printer and is generally not accessible to a user of the printer.
2 © ISO/IEC 2018 – All rights reserved
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ISO/IEC 29112:2018(E)
3.1.11
human eye modulation response

response of the human visual system to viewed sinusoidal modulation (3.1.15) patterns as a function of

the spatial frequency of these modulation patterns
3.1.12
in-track
oriented along the direction of print substrate motion
3.1.13
in-track addressability

addressability (3.1.1) of the printer in the direction parallel to the motion of the print substrate through

the printer
3.1.14
limiting resolution

spatial frequency at which the modulation (3.1.15) of alternating printed high-contrast lines and spaces

is 10 % of the zero-frequency spatial frequency response of the printing system
3.1.15
modulation

difference between the maximum and minimum signal levels divided by the sum of these two levels

3.1.16
modulation transfer function
MTF
spatial frequency response
SFR

ratio, as a function of spatial frequency, of the measured modulation (3.1.15) response in a print

produced by a printing system, to the stimulus modulation presented to that printing system

3.1.17
monochrome
printing using a single colorant, in particular, a single black colorant
3.1.18
native addressability

one over the minimum pitch between adjacent spots (3.1.35) that can be independently controlled and

produced by the printer
3.1.19
normal edge profile
NEP

reflectance trace across the transition region perpendicular to the boundary of a straight edge between

an unprinted substrate area and a solid printed area

Note 1 to entry: For the edge blurriness measurement specified in this document, the transition region is

measured between the 10 % and 70 % reflectance levels.

Note 2 to entry: The normal edge profile can be represented as the convolution of an edge spread function and

an infinitely sharp edge transition. In turn, for a linear system, the edge spread function is the Fourier transform

of the spatial frequency response (or modulation transfer function). For printing systems, which are usually not

linear systems, this latter relationship is only approximate.
3.1.20
Nyquist limit
Nyquist frequency

spatial frequency equal to one half the inverse of the sampling spacing for an adjacent pair of

sampling points

Note 1 to entry: This can also be expressed as one half of the spatial sampling frequency.

© ISO/IEC 2018 – All rights reserved 3
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ISO/IEC 29112:2018(E)
3.1.21
pixel
smallest addressable element of a digital source image
3.1.22
raster image processor
RIP
component used in a printing system which produces a bitmap (3.1.2)
3.1.23
reflectance factor

ratio of the reflected flux as measured to the reflected flux under the same geometrical and spectral

conditions for an ideal 100 % diffuse reflecting surface
3.1.24
resolution enhancement technology

control of the printed spot (3.1.36) position to a pitch that is less than the native addressability (3.1.18)

of the printing system accomplished through local control of one or more spot characteristics

Note 1 to entry: The spot characteristics are spot reflectance (gray-level modulation), size of a spot (size

modulation) or local position of a spot (position modulation).
3.1.25
reflectance threshold

level in the reflectance gradient profile of an edge that is at some specified percentage of the transition

from the minimum reflectance factor, R (3.1.27), to the maximum reflectance factor, R (3.1.26),

min max
as: R = R + p%(R – R )
p min max min
3.1.26
max
maximum measured reflectance factor (3.1.23), typically of the substrate
3.1.27
min

minimum measured reflectance factor (3.1.23), typically of a region printed at a maximum printing value

3.1.28

contour of points of an image element where the edge gradient profiles cross a reflectance level that

is 10 % of the transition from the substrate reflectance factor, R (3.1.26), to the minimum image

max
reflectance factor, R (3.1.27): R = R + 10 % (R – R )
min 10 min max min
3.1.29

contour of points of an image element where the edge gradient profiles cross a reflectance level that

is 25 % of the transition from the substrate reflectance factor, R (3.1.26), to the minimum image

max
reflectance factor, R (3.1.27): R = R + 25 % (R – R )
min 25 min max min
3.1.30

contour of points of an image element where the edge gradient profiles cross a reflectance level that

is 40 % of the transition from the substrate reflectance factor, R (3.1.26), to the minimum image

max
reflectance factor, R (3.1.27): R = R + 40 % (R – R )
min 40 min max min
3.1.31

contour of points of an image element where the edge gradient profiles cross a reflectance level that

is 70 % of the transition from the substrate reflectance factor, R (3.1.26), to the minimum image

max
reflectance factor, R (3.1.27): R = R + 70 % (R – R )
min 70 min max min
4 © ISO/IEC 2018 – All rights reserved
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ISO/IEC 29112:2018(E)
3.1.32
sampling efficiency

fraction of the Nyquist frequency (3.1.20) corresponding to the frequency where the spatial frequency

response characteristic (3.1.16) has dropped to 10% of its zero-frequency value
3.1.33
sampling frequency

spatial frequency of adjacent sampling points where sampling points are conventionally oriented along

the direction of print substrate motion, the in-track direction (3.1.12), or perpendicular to the direction

of print substrate motion, the cross-track direction (3.1.3)
3.1.34
scanner tone-scale calibration
opto-electronic conversion function
OECF

digital signal conversion that adjusts the relationship between the reflectance values of large imaged

areas and the corresponding digital code values

Note 1 to entry: Code values are the reflection scanner response to a scanned reflection stimulus, e.g. test

elements (3.1.37). Scanner tone-scale calibration can be used to adjust the relationship between scanned pixel

values and large area reflectance to an aim relationship, e.g. scanned pixel values that have a linear relationship

with measured print reflectance.
3.1.35
spot

smallest mark that can be placed under user control at a desired position on a printed page,

independently from all other adjacent marks
3.1.36
tangential edge profile
TEP

array of geometric positions of a contour at a specific reflectance threshold (3.1.25) along the printed

rendition of a perfectly straight edge boundary between an unprinted substrate area and a solid

printed area

Note 1 to entry: For the edge raggedness measure specified in this document, the contour is taken at a 40 %

reflectance level.
...

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