ISO/TS 19567-1:2016

TECHNICAL ISO/TS
SPECIFICATION 19567-1
First edition
Photography — Digital cameras
— Texture reproduction
measurements —
Part 1:
Frequency characteristics
measurements using cyclic pattern
Photographie — Caméras numériques — Mesurages de la
reproduction de la texture —
Partie 1: Mesurages des caractéristiques de fréquence en utlisant un
modèle cyclique
PROOF/ÉPREUVE
Reference number
ISO/TS 19567-1:2016(E)
©
ISO 2016

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ISO/TS 19567-1:2016(E)

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© ISO 2016, Published in Switzerland
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ISO/TS 19567-1:2016(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test conditions . 1
4.1 General . 1
4.2 Environments for measurement . 2
4.3 Apparatus and hardware . 2
4.4 Arrangement of measuring equipment . 2
4.4.1 Reflective test chart . 2
4.4.2 Transmissive test chart . 2
4.5 Lighting . 3
4.6 Camera settings . 3
5 Texture reproduction measurement procedure . 4
5.1 General . 4
5.2 Multiburst measurement . 5
5.2.1 Low contrast multiburst chart . 5
5.2.2 Measurement method . 6
5.3 Siemens star measurement . 7
5.3.1 Low contrast sine siemens star chart . 7
5.3.2 Measurement method . 7
6 Presentations of results . 8
6.1 General . 8
6.2 Multiburst measurement . 8
6.3 Siemens star measurements . 9
Annex A (informative) Categorization of texture.10
Annex B (informative) Exposure condition for the measurement .11
Annex C (informative) Interpretation of measurement results .14
Annex D (informative) Measurement results of multiburst and siemens star .16
Bibliography .20
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ISO/TS 19567-1:2016(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 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.
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ISO/TS 19567-1:2016(E)

Introduction
Texture generally means the visual and tactile surface quality derived from the physicality of the
material and the roughness or graininess of the surface. For digital still cameras, texture is of course
the visual surface quality and the characteristic of texture reproduction in the captured image is
interpreted into the reproduction of the low contrast fine details. This Technical Specification specifies
the measurement of how cameras reproduce texture defined as low contrast fine details.
The tendency to utilize small sensors with high pixel counts in some cameras leaves a very small amount
of light reaching the individual pixel. With the signal getting smaller and the noise level remaining at
a certain level, it is necessary to reduce the noise in the image processing after capturing the image.
Although the algorithms used for noise reduction have been developed over time, they are still not able
to differentiate texture in the actual scene from the unwanted noise introduced by the capturing system.
This decreases the image quality and it is therefore helpful to have a method to measure the loss of
texture. Texture can also be enhanced to increase the acutance of the image. The texture reproduction
is dependent on frequency and contrast because the noise reduction and the acutance enhancement,
etc. are nonlinearly dependent on the pixel value and the difference among the surrounding pixels.
This part of ISO 19567 specifies methods to measure texture reproduction using test charts with cyclic
patterns. The test charts are based on the established measurement methods, multiburst (IEC 61146-
1) and siemens star (ISO 12233). This part of ISO 19567 newly defines the density of the test charts
and exposure setting of measured cameras. The measurement results are presented in the spatial
frequency response (SFR) curves.
If one SFR is larger than the other in all frequency range, larger amount of texture is reproduced in the
corresponding image. If two SFRs have a cross point and the larger SFR depends on the frequency range,
the superior image in the subjective evaluation is dependent on the dominant frequency of the image.
Comparison of the measurement result provides important information in the texture comparison of
the captured images.
Texture in a real scene consists mostly of non-structured or random patterns as shown in Annex A.
Although it has been confirmed by experiments (Annex C and Annex D) that the texture reproduction
characteristics of most cameras are well represented by the measurements in this Technical
Specification, some cameras are found to indicate different characteristics for structured patterns
compared to those for non-structured patterns. Measurement methods using non-structured or
random patterns are under study and are expected to be included in consequent parts to this Technical
Specification.
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TECHNICAL SPECIFICATION ISO/TS 19567-1:2016(E)
Photography — Digital cameras — Texture reproduction
measurements —
Part 1:
Frequency characteristics measurements using cyclic
pattern
1 Scope
This part of ISO 19567 specifies a protocol to measure the texture reproduction in the images captured
and processed by digital cameras including cameras in other devices, e.g. in camera phones.
This part of ISO 19567 specifies protocols for the measurement of the texture reproduction using test
charts with cyclic pattern.
This part of ISO 19567 excludes the acceptable range of value for texture reproduction.
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.
IEC 61966-2-1:1999, Multimedia systems and equipment — Colour measurement and management —
Part 2-1: Colour management — Default RGB colour space —sRGB
IEC 61966-2-1/Amd 1:2003, Multimedia systems and equipment — Colour measurement and
management — Part 2-1: Colour management — Default RGB colour space —sRGB
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
texture
low contrast fine details, which appear in objects
EXAMPLE Low contrast fine details, which is visible in foliage, fur, sand, textiles, grass, or masonry surfaces.
3.2
texture reproduction
response in the output image of cameras to the texture of the object in the scene
4 Test conditions
4.1 General
The following measurement conditions should be used as nominal conditions when measuring the
texture reproduction of a digital camera.
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ISO/TS 19567-1:2016(E)

4.2 Environments for measurement
The measurement shall be carried out in the following environment unless otherwise stated:
— Temperature: 23 °C ± 3 °C
4.3 Apparatus and hardware
Either a reflective chart or a transmissive chart may be used. The light flux from the target shall be
diffused and shall not include any specular component.
4.4 Arrangement of measuring equipment
4.4.1 Reflective test chart
The arrangement of the measuring equipment for a reflective test chart shall be set up as shown in
Figure 1. The camera shall be positioned so that it casts no shadow on the chart. The lamps shall be
positioned at an angle which avoids direct specular reflection from the test chart entering the camera.
f
Figure 1 — Arrangement of measuring equipment for reflective test chart
4.4.2 Transmissive test chart
The arrangement of the measuring equipment for a transmissive test chart shall be set up as shown in
Figure 2.
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ISO/TS 19567-1:2016(E)

Figure 2 — Arrangement of measuring equipment for transmassive test chart
4.5 Lighting
Colour temperature of illumination shall be 5 700 K ± 1 000 K. Any illuminance level of the test chart
may be applied for the texture reproduction measurement; however, the illuminance level in the range
from 1 000 lx to 2 000 lx (in the case of transmissive chart, from 57,3 cd/m2 to 115 cd/m2 for 18 %
gray) is recommended when the measurement has no specified purpose (e.g. low light performance).
Non-uniformity of illumination on the chart shall be less than 10 %. The light source(s) should be
positioned to provide uniform illumination and produce no glare or specular reflections from the target.
A flickering light source is not recommended as it may cause banding artefacts to occur in the captured
image. In the case of using a flickering light source, although it is not recommended, the exposure time
shall not be shorter than one period of the flickering to minimize the banding artefacts caused by the
light source.
4.6 Camera settings
The exposure should be adjusted to give the output value for the background gray near the centre of the
measured chart to be the value corresponding to the input value defined below in the camera’s output
colour space.
(input luminance for gray) = (max input luminance) × (gray reflectance)
For sRGB cameras, the output Y for 18 % gray is 118 (8-bit).
The deviation of the exposure should be between +5 % and −10 % of the aforementioned target
exposure. For example, the mean output luminance Y value for the 18 % gray should be 118 (8-bit) +2,
−6 when the output colour space of the camera is sRGB 8-bit (IEC 61966-2-1 and IEC 61966-2-1/Amd 1).
The exposure shall be in the range of the aforementioned deviation when the measurement results
of multiple cameras are compared (Annex A explains the basic concept for this stipulation). The
exposure can be adjusted by the exposure bias setting of the camera or by adding a white or black
card to the test chart.
White balance should be adjusted to render the centre of the image, as neutral as possible.
The focusing shall be in the best practically attainable focus.
For a camera with user selectable compression ratio (e.g. JPEG), the compression ratio should be
minimum to minimize the artefacts of compression. The texture reproduction for RAW format image
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data should be measured for the output of the RAW converter software. The name and the setting of the
RAW converter shall be reported with the results of the measurement.
Other settings, such as “sharpness”, “noise reduction”, shall be in the default mode (factory shipping
condition) if those settings are not reported.
5 Texture reproduction measurement procedure
5.1 General
Texture reproduction is measured by the amplitude of a sine waveform in this part of ISO 19567. The
frequency characteristics of the texture reproduction are measured for various frequencies in the sine
chart to be captured.
Two measurement methods, the multiburst and siemens star, are defined in this part of ISO 19567.
The multiburst chart consists of several low contrast sine waves of discrete frequency (see Figure 3).
Each sine wave consists of multiple cyclic patterns along a single direction in the multiburst chart. The
siemens star chart consists of a low contrast sine wave-modulated star burst pattern (see Figure 4),
which includes continuous frequency variation in all directions. Based on the structure of each chart,
the multiburst and the siemens star can be used in the cases shown in Table 1.
Table 1 — Guidance for selecting the measurement
Multiburst Siemens star
(1) In the case of measuring SFR with verification of (1) In the case of measuring SFR by simply applying
the waveform and the amplitude of the captured the software to the captured image.
image.
(1–1)  In the case when skilled engineer recognizes
...