Photography — Lenticular print for changing images — Measurements of image quality

This document specifies the measurement methods and specification of image quality of lenticular prints that are used for changing images. This document does not cover lenticular prints that are used for 3D images. NOTE Lenticular prints for 3D images can be measured with the same types of procedures. However, it needs more information, such as the dependence of the measurement distance, to evaluate the 3D performance. This document specifically describes measurement methods for cross-talk, viewing angle range, angular misalignment from the designed viewing angle and the uniformity of the image within the printing area of the lenticular print images. These are critical for the image quality of lenticular prints for changing images. This document is applicable to lenticular prints produced by printing technologies that include impact and non-impact printing. Examples of the former are off-set, gravure and flexography, while the examples of the latter are silver halide, inkjet, dye diffusion thermal transfer and electrophotography. The multiple laser images (MLI) and changeable laser images (CLI) process of using a laser to write through a lenticular screen at different angles to create multiple images is also used.

Photographie — Impression lenticulaire pour images changeantes — Mesurages de la qualité des images

General Information

Status
Published
Publication Date
31-Mar-2019
Current Stage
9092 - International Standard to be revised
Completion Date
09-Mar-2023
Ref Project

Buy Standard

Technical specification
ISO/TS 20793:2019 - Photography -- Lenticular print for changing images -- Measurements of image quality
English language
22 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 20793
First edition
2019-04
Photography — Lenticular print for
changing images — Measurements of
image quality
Photographie — Impression lenticulaire pour images changeantes —
Mesurages de la qualité des images
Reference number
ISO/TS 20793:2019(E)
©
ISO 2019

---------------------- Page: 1 ----------------------
ISO/TS 20793:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
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 2019 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 20793:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Terms . 1
3.2 Abbreviations . 2
4 Standard environmental conditions . 2
4.1 Temperature and humidity . 2
4.2 Ambient illumination conditions . 2
5 Measurement conditions . 2
5.1 General . 2
5.2 Geometry of measurements . 2
5.2.1 Standard conditions with hemispherical illumination . 2
5.2.2 Optional conditions with directional illumination . 3
5.3 Light source . 4
5.4 Light measuring device (LMD) . 4
5.5 Working standards and references. 5
6 Preparation of lenticular print samples . 6
6.1 Test pattern . 6
6.2 Printing . 7
6.3 Construction of a lenticular print . 7
7 Measurements and calculations . 8
7.1 General . 8
7.2 Measurements of angular dependence . 8
7.3 Calculation of cross-talk, viewing angle range and angular misalignment. 9
7.4 Uniformity in the printing area .10
8 Classifications .11
8.1 General .11
8.2 Cross-talk .11
8.3 Viewing angle range .11
8.4 Angular misalignment .12
8.5 Uniformity in the printing area .12
Annex A (informative) Explanation of a lenticular lens print .13
Annex B (informative) Procedures of lenticular printing .15
Annex C (informative) Selection and receiving inspection of lenticular lens sheets .21
Bibliography .22
© ISO 2019 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/TS 20793:2019(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 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.
This document was prepared by Technical Committee ISO/TC 42, Photography.
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.
iv © ISO 2019 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 20793:2019(E)

Introduction
Lenticular printing is a technology wherein lenticular lenses are used to produce printed images with
an illusion of depth, i.e. three-dimensional (3D) effect, or the ability to change or move as the image is
viewed from different angles. Lenticular prints to display changing images are built up with a lenticular
lens sheet and a printed sheet that contains at least two images, interleaved with the same spacial
frequency as the lenticular lens sheet.
Lenticular lenses are an array of magnifying lenses.
Widespread applications of lenticular printing are signage, display posters, business cards, multilingual
message boards and packages with changing images or 3D effects.
2
It has been reported that the market size of lenticular prints is over 100 million m and that the
market is growing. Furthermore, the potential image qualities of lenticular printing have dramatically
improved and further improvements are expected in the future. While production of lenticular sheets
with a lens frequency of 100 lpi (lines per inch) is routine, products with a 200 lpi frequency are also
currently available.
Although the potential image quality of lenticular prints is high as described above, the quality of
images is not always good in the market due to various causes, e.g., due to the misalignment of the
lenticular lens and lenticular printed images. This is a critical problem for lenticular printing.
To improve the image quality of lenticular prints, image quality measurements are essential. This
document provides standard measurement methods and the specifications for the image quality of
lenticular prints.
© ISO 2019 – All rights reserved v

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 20793:2019(E)
Photography — Lenticular print for changing images —
Measurements of image quality
1 Scope
This document specifies the measurement methods and specification of image quality of lenticular
prints that are used for changing images. This document does not cover lenticular prints that are used
for 3D images.
NOTE Lenticular prints for 3D images can be measured with the same types of procedures. However, it
needs more information, such as the dependence of the measurement distance, to evaluate the 3D performance.
This document specifically describes measurement methods for cross-talk, viewing angle range,
angular misalignment from the designed viewing angle and the uniformity of the image within the
printing area of the lenticular print images. These are critical for the image quality of lenticular prints
for changing images.
This document is applicable to lenticular prints produced by printing technologies that include impact
and non-impact printing. Examples of the former are off-set, gravure and flexography, while the
examples of the latter are silver halide, inkjet, dye diffusion thermal transfer and electrophotography.
The multiple laser images (MLI) and changeable laser images (CLI) process of using a laser to write
through a lenticular screen at different angles to create multiple images is also used.
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 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
3 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 Terms
3.1.1
lenticular lens
array of magnifying semi-cylindrical lenses, designed to produce a desired perception, such as 3D,
motion or morphing, to the underlying interlaced image
EXAMPLE This technique is widely used in lenticular printing, wherein the lenticular lens is used to provide
an illusion of depth, change or motion to an underlying interlaced image when viewed from different angles.
[SOURCE: ISO/TS 20328:2016, 3.1, modified — Note 1 to entry has been removed.]
© ISO 2019 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO/TS 20793:2019(E)

3.1.2
lenticular print
print combined with lenticular lenses which produces printed images with an illusion of depth, i.e. three-
dimensional (3D) effect, or the ability to change or move as the image is viewed from different angles
Note 1 to entry: The detailed explanation of lenticular print is provided in Annex A.
Note 2 to entry: Lenticular prints to display changing images are built up with a lenticular lens sheet and a printed
sheet that contains at least two images, interleaved with the same special frequency as the lenticular lens sheet.
3.2 Abbreviations
CIE commission internationale de l'éclairage (International Commission on Illumination)
CTP computer to plate
LMD light measuring device
LPS lenticular print sample
RGB red, green, blue
4 Standard environmental conditions
4.1 Temperature and humidity
The standard environmental conditions shall be applied for the measurements of lenticular prints.
The standard environmental conditions shall be a temperature of 23 °C ± 3 °C and a humidity of
50 % RH ± 15 % RH.
4.2 Ambient illumination conditions
For standard dark room conditions, the ambient illuminance at any position on the lenticular print is
below 0,3 lx in all directions or the illuminance shall at least be less than a level that does not influence
the measurement results.
When directional illumination is used, standard dark room conditions shall be applied unless the
instrumentation used is effective in suppressing background illumination.
When the sample is set in an integrated sphere, dark room may not be required.
5 Measurement conditions
5.1 General
For the measurements, the lenticular print samples shall be illuminated with hemispherical diffuse
lighting. Directional illumination can also be used when it is appropriate for simulating the use
application.
The reflected light from the print sample shall be measured using a spectroradiometer.
5.2 Geometry of measurements
5.2.1 Standard conditions with hemispherical illumination
Uniform hemispherical diffuse illumination is generally realized by using an integrating sphere. The
lenticular print sample (LPS) shall be placed in the centre of an integrating sphere as shown in Figure 1.
2 © ISO 2019 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/TS 20793:2019(E)

For the calibration, the reflection standard, i.e. a standard white board, shall be placed at the same
position of the LPS. Best practices for integral sphere design and measurements are described in
References [2] and [3].
When the viewing direction dependence is measured, the print sample shall be rotated around the axis
parallel to the direction of the array of lenticular lens.
Key
1 lenticular print 4 baffle
2 integration sphere 5 light measurement device
a
3 light source Reflected light from sample.
Figure 1 — Geometry of measurement with hemispherical illumination
5.2.2 Optional conditions with directional illumination
The directional light shall be illuminated at an angle of 45° from the normal, and the reflected light
shall be detected from the direction normal to the print as shown in Figure 2. The light source and the
detector shall be placed in the same plane. The lenticular print shall first be set normal to the detector,
and it shall be rotated from the normal direction in order to measure the viewing angle dependence.
© ISO 2019 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO/TS 20793:2019(E)

Key
b
1 lenticular print Reflected light.
c
2 light source — directional Angle of the incident light = 45°.
d
3 detector Angle of the detection = 90°.
a e
Incident light. Angle of rotation of the print.
Figure 2 — Geometry of measurement with directional illumination
5.3 Light source
For the standard conditions, hemispherical illumination shall be applied. The illumination spectra shall
be a stable and spectrally continuous broadband visible light source, for example, an incandescent lamp
defined as CIE Standard Illuminant A.
5.4 Light measuring device (LMD)
The light reflected from the lenticular print shall be measured. Illuminant D50 shall be applied. The
following requirements are given for measurement instrument:
a) The spectroradiometer shall be capable of measuring spectral radiance over at least the 380 nm to
780 nm wavelength range, with a maximum bandwidth of 10 nm for smooth broadband spectra.
Care shall be taken to ensure that the LMD has enough sensitivity and dynamic range to perform
the required task. The measured LMD signal shall be at least ten times greater than the dark level
(noise floor) of the LMD, and no greater than 85 % of the saturation level.
b) The LMD shall be focused on the image plane of the print and aligned perpendicular to its surface,
unless stated otherwise.
c) The relative uncertainty and repeatability of all the measuring devices shall be maintained by
following the instrument supplier’s recommended calibration schedule.
d) The recommended measuring distance is between 35 cm to 60 cm. The measuring distance shall
be noted in the report.
4 © ISO 2019 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/TS 20793:2019(E)

e) The angular aperture shall be less than or equal to 5°, and the measurement field angle shall be less
than or equal to 2° (see Figure 3).
f) The measurement field of the LMD shall be centred and enclosed within the illuminated measuring
spot on the print.
Key
c
1 lenticular print Measurement area (measurement field).
d
2 LMD Angular aperture.
a e
Measuring distance. Aperture area.
b
Measurement area angle (measurement field angle).
Figure 3 — Layout diagram of measurement setup
5.5 Working standards and references
The LMD shall be calibrated with a diffuse white reflectance standard sample with a diffuse reflectance
of 98 % or more. The reflectance shall be calculated based on the reflectance of the perfect white panel
and the black panel.
Diffuse white reflectance standard samples can be obtained with a diffuse reflectance of 98 % or more.
They are also available in different shades of grey. A luminance L measurement from such reflectance
std
standards can be used to determine the illuminance E on the standard for a defined detection geometry
and illumination spectra and configuration:
πL
std
E= (1)
R
std
where R is the calibrated luminous reflectance factor for that measurement configuration. When
std
the illumination configuration is a uniform hemispherical illumination, then R is equivalent to
std
luminous reflectance ρ . The luminous reflectance value associated with the standard is only valid
std
for the hemispherical illumination in which it was calibrated. If it is used with a directed source at any
angle, there is no reason to expect that t
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.