ISO/DIS 13322-2

Particle size analysis -- Image analysis methods

Analyse granulométrique -- Méthodes par analyse d'images

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 13322-2
ISO/TC 24/SC 4 Secretariat: BSI
Voting begins on: Voting terminates on:
2020-01-03 2020-03-27
Particle size analysis — Image analysis methods —
Part 2:
Dynamic image analysis methods
Analyse granulométrique — Méthodes par analyse d'images —
Partie 2: Méthodes par analyse d'images dynamiques
ICS: 19.120
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ISO/DIS 13322-2:2020(E)
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ISO/DIS 13322-2:2020(E)
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ISO/DIS 13322-2:2019(E)
Contents Page

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

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

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

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

3 Terms, definitions and symbols .................................................................................................................2

3.1 Terms and definitions ....................................................................................................................................2

3.2 Symbols ...............................................................................................................................................................5

4 Principle ..............................................................................................................................................................6

4.1 Key components of a dynamic image analyser .....................................................................................6

4.2 Illumination .......................................................................................................................................................8

4.3 Particle motion .............................................................................................................................................. 10

4.4 Particle positioning ...................................................................................................................................... 10

4.5 Optical system ................................................................................................................................................ 12

4.6 Image capture device .................................................................................................................................. 13

4.7 Image Analysis Methods ............................................................................................................................. 14

4.8 Conversion to meaningful particle descriptors ................................................................................. 16

4.9 Statistical representation of descriptors ............................................................................................. 16

4.10 Particle dispersion technique .................................................................................................................. 16

4.11 Systematic corrections dealing with set-up characteristics ......................................................... 16

5 Operational procedures ............................................................................................................................. 16

5.1 General ............................................................................................................................................................. 16

5.2 Instrument set-up and calibration ......................................................................................................... 17

5.3 Dispersing systems ...................................................................................................................................... 19

5.4 Operational and performance qualification ....................................................................................... 21

5.5 Image enhancement algorithms .............................................................................................................. 21

5.6 Measurements ............................................................................................................................................... 21

6 Sample preparation ..................................................................................................................................... 22

6.1 Sample splitting and reduction ............................................................................................................... 22

6.2 Touching Particles ........................................................................................................................................ 23

6.3 Number of Particles to be counted ......................................................................................................... 23

7 Accuracy and Instrument Qualification ................................................................................................ 23

7.1 General ............................................................................................................................................................. 23

7.2 Trueness .......................................................................................................................................................... 23

7.3 Repeatability .................................................................................................................................................. 24

7.4 Intermediate Precision ............................................................................................................................... 25

8 Sample and measurement variability ................................................................................................... 26

9 Reporting of results ..................................................................................................................................... 26

(informative) Theoretical Background ............................................................................................ 28

A.1 Object and image planes ............................................................................................................................ 28

A.2 Object and image space telecentric lenses .......................................................................................... 28

A.3 Lens aberrations and distortions ........................................................................................................... 29

A.4 Optical resolution ......................................................................................................................................... 30

(informative) Comparison between particle size distributions by number and by

volume .............................................................................................................................................................. 31

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B.1 Example ........................................................................................................................................................... 31

(informative) Recommended particle velocity and exposure time ....................................... 32

(informative) Particle diameter dependence on threshold selection .................................. 35

D.1 General ............................................................................................................................................................. 35

D.2 Influence of the threshold selection caused by the pixel structure of digital images ......... 35

D.3 Influence of the threshold selection for particles within and outside the depth of

field.................................................................................................................................................................... 36

(normative) Requirements for reference material ..................................................................... 39

E.1 Calibration standards ................................................................................................................................. 39

E.2 General requirements for particulate reference materials suitable for image

analysis ............................................................................................................................................................ 39

E.3 Selection of spherical certified reference materials ....................................................................... 40

E.4 Selection and characterisation of non-spherical reference materials ..................................... 40

E.5 Calculation of the acceptance limits (informative example)........................................................ 41

(informative) Robustness and ruggedness of the image analysis method .......................... 43

F.1 Robustness...................................................................................................................................................... 43

F.2 Ruggedness ..................................................................................................................................................... 43

F.3 Investigation of parameters ..................................................................................................................... 43

F.4 Examples ......................................................................................................................................................... 44

(informative) Optional Methods......................................................................................................... 46

G.1 Particle tracking methods ......................................................................................................................... 46

G.2 Spectral evaluation ...................................................................................................................................... 46

(informative) Typical examples of sample feed and image capture systems .................... 47

H.1 Sheath flow system ...................................................................................................................................... 47

H.2 Electrical sensing zone system ................................................................................................................ 48

H.3 Circulating method ...................................................................................................................................... 48

H.4 Agitating method .......................................................................................................................................... 49

H.5 Dynamic stop-flow image analysis method ........................................................................................ 50

H.6 Free-falling system ...................................................................................................................................... 51

H.7 Measurement on a moving substrate .................................................................................................... 52

H.8 Measurement at a conveyor discharge point ..................................................................................... 53

Bibliography ................................................................................................................................................................. 54

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ISO/DIS 13322-2:2019(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 on 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/foreword.html.

The committee responsible for this document is Technical Committee ISO/TC 24, Particle

characterization including sieving, Subcommittee SC 4, Particle characterization.

This second edition cancels and replaces the first edition (ISO 13322-2:2006), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— consideration of changes to the last revision of ISO 13322-1:2014

— significantly expanded sections on instrumentation (principle) and operational procedures

— new section on accuracy and instrument qualification using particulate reference materials

A list of all parts in the ISO 13322 series can be found on the ISO website.
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ISO/DIS 13322-2:2019(E)
Introduction

The purpose of this second part of ISO 13322 is to provide guidance for measuring and describing particle

size distribution, using image analysis methods where particles are in motion. This entails using

techniques for dispersing particles in liquid or gas, taking in-focus, still images of them while the particles

are moving and subsequently analysing the images. This methodology is called dynamic image analysis.

There are several image capture methods. Some typical methods are described in this second part of

ISO 13322.
Identification of patent holders, if any.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 13322-2:2020(E)
Particle size analysis — Image analysis methods —
Part 2:
Dynamic image analysis methods
1 Scope

ISO 13322 is applicable to the analysis of images for the purpose of determining particle size

distributions.

ISO 13322-1 on static image analysis methods assumes that an adequate binary image has already been

captured and concentrates upon the analysis of these images.

ISO 13322-2 describes the transfer of images from particles having relative motion to binary images

within practical systems, in which the particles are highly diluted. Images of moving particles are created

by an optical image capture device. Effects of particle movement on the images are either minimized by

the instrumentation or corrected by software procedures. The application of this method requires the

particle images to be clearly distinguishable from a static background. Further processing of the binary

image, which is then considered as static, is described in ISO 13322-1. A dynamic image analysis system

is capable of measuring higher number of particles compared to static image analysis systems. This

International Standard provides guidance on instruments qualification and particle size distribution

measurement by using particulate reference materials. This part addresses the relative movement of the

particles with respect to each other, the effect of particle movement on the image (motion blur), the

movement and position along the optical axis (depth of field), and the orientation of the particles with

respect to the camera.
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 13322-1:2014, Particle size analysis — Image analysis method — Part 1: Static image analysis methods

ISO 9276-1, Representation of results of particle size analysis — Part 1: Graphical representation

ISO 9276-2, Representation of results of particle size analysis — Part 2: Calculation of average particle

sizes/diameters and moments from particle size distributions

ISO 9276-6, Representation of results of particle size analysis — Part 6: Descriptive and quantitative

representation of particle shape and morphology

ISO 14488:2007, Particulate materials — Sampling and sample splitting for the determination of

particulate properties

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

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3 Terms, definitions and symbols
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 13322-1:2014 and the following

apply.
3.1.1
acceptable depth of field

depth with respect to focal depth where the sharpness of the edges of the

particle images is accepted for segmentation
3.1.2
accuracy

closeness of agreement between a test result or measurement result and the true value

Note 1 to entry: In practice, the accepted reference value is substituted for the true value.

Note 2 to entry: The term “accuracy”, when applied to a set of test or measurement results, involves a

combination of random components and a common systematic error or bias component.

Note 3 to entry: Accuracy refers to a combination of trueness and precision.
[Source, ISO 3534‐2:2006, clause 3.3.1]
3.1.3
certified reference material
CRM

reference material (RM) characterised by a metrologically valid procedure for one or more specified

properties, accompanied by an RM certificate that provides the value of the specified property, its

associated uncertainty, and a statement of metrological traceability

Note 1 to entry: The concept of value includes a nominal property or a qualitative attribute such as

identity or sequence. Uncertainties for such attributes may be expressed as probabilities or levels of

confidence.

Note 2 to entry: Metrologically valid procedures for the production and certification of RMs are given in,

among others, ISO 17034 and ISO Guide 35.
Note 3 to entry: ISO Guide 31 gives guidance on the contents of RM certificates.
Note 4 to entry: ISO/IEC Guide 99:2007 has an analogous definition (5.14).
[Source, ISO Guide 35:2017, 3.2]
3.1.4
flow-cell
measurement cell inside which the fluid-particle mixture flows
3.1.5
frame coverage

fraction of the image area that is obscured by the projection area of all

segmented particles in the image
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ISO/DIS 13322-2:2019(E)

Note to entry: Frame coverage can be expressed as a part or percentage of image area.

3.1.6
image capture device

matrix camera or line scan camera for converting an optical image to digital image data

3.1.7
measurement zone

volume in which particles are measured by an image analyser. The measurement zone is formed by the

measurement frame including a third dimension from the acceptable depth of field.

Note 1 to entry: the measurement zone is defined by the software
3.1.8
orifice tube

tube with an aperture through which a stream of fluid with dispersed particles flows

3.1.9
particle illumination

continuous illumination for image capture device with an electronic exposure time controller, or

illumination of short duration for synchronized image capture device
3.1.10
precision

closeness of agreement between independent test/measurement results obtained under stipulated

conditions

Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to the

true value or the specified value.

Note 2 to entry: The measure of precision is usually expressed in terms of imprecision and computed as

a standard deviation of the test results or measurement results. Less precision is reflected by a larger

standard deviation.

Note 3 to entry: Quantitative measures of precision depend critically on the stipulated conditions.

Repeatability conditions and reproducibility conditions are particular sets of extreme stipulated

conditions.
[Source, ISO 3534‐2:2006, clause 3.3.4]
3.1.11
reference material

material, sufficiently homogeneous and stable with respect to one or more specified properties, which

has been established to be fit for its intended use in a measurement process
Note 1 to entry: RM is a generic term.

Note 2 to entry: Properties can be quantitative or qualitative, e.g. identity of substances or species.

Note 3 to entry: Uses may include the calibration of a measurement system, assessment of a measurement

procedure, assigning values to other materials, and quality control.
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Note 4 to entry: ISO/IEC Guide 99:2007[3] has an analogous definition (5.13), but restricts the term

“measurement” to apply to quantitative values. However, ISO/IEC Guide 99:2007, 5.13, Note 3 (VIM),

specifically includes qualitative properties, called “nominal properties”.
[Source, ISO Guide 35:2017, 3.1]
3.1.12
repeatability
precision under repeatability conditions

Note 1 to entry: Repeatability can be expressed quantitatively in terms of the dispersion characteristics

of the results.
[Source ISO 3534‐2:2006, clause 3.3.5]
3.1.13
repeatability conditions

observation conditions where independent test/measurement results are obtained with the same

method on identical test/measurement items in the same test or measuring facility by the same operator

using the same equipment within short intervals of time
Note 1 to entry: Repeatability conditions include:
— the same measurement procedure or test procedure;
— the same operator;
— the same measuring or test equipment used under the same conditions;
— the same location;
— repetition over a short period of time.
[Source, ISO 3534‐2:2006, clause 3.3.6]
3.1.14
sampling volume

volume in which the particles are within the field of view of the image analyser including a third

dimension from the sampling volume depth
3.1.15
sampling volume depth
length which describes the extent of the particle field in front of the camera
3.1.16
sheath flow

clean fluid flow surrounding particle-laden fluid for directing particles into a specific measurement zone

3.1.17
trueness

closeness of agreement between the expectation of a test result or a measurement result and a true value

Note 1 to entry: The measure of trueness is usually expressed in terms of bias.
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Note 2 to entry: Trueness is sometimes referred to as “accuracy of the mean”. This usage is not

recommended.

Note 3 to entry: In practice, the accepted reference value is substituted for the true value.

[Source, ISO 3534‐2:2006, clause 3.3.3]
3.1.18
true value

value which characterizes a quantity or quantitative characteristic perfectly defined in the conditions

which exist when that quantity or quantitative characteristic is considered

Note 1 to entry: The true value of a quantity or quantitative characteristic is a theoretical concept and, in

general, cannot be known exactly.

Note 1 to entry: For an explanation of the term “quantity”, refer to [ISO 3534‐2:2006.]

3.2 Symbols
a moving distance of a particle during time t
A projected area of particle i
b measured diameter of binary image
CF coverage factor

𝐷 particle diameter corresponding to 10 % of the cumulative undersize distribution

��,�

𝐷 particle diameter corresponding to 50 % of the cumulative undersize distribution

��,�

𝐷 particle diameter corresponding to 90 % of the cumulative undersize distribution

��,�
𝑄 cumulative undersize distribution of quantity r
r quantity type; number (𝑟 = 0), area (𝑟 = 2) or volume (𝑟 = 3)
s standard deviation of the test samples
 standard deviation
t exposure time
𝑢 measurement uncertainty
𝑢 uncertainty of an assigned values of a certified reference material
CRM
𝑢 uncertainty of a characterized values of a reference material

𝑈 total value of the uncertainty used as the final acceptance/rejection limits for qualification tests

lim
v particle velocity
x or D diameter of particle

𝑥 particle diameter corresponding to 10 % of the cumulative undersize distribution

��,�
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𝑥 particle diameter corresponding to 50 % of the cumulative undersize distribution

��,�

𝑥 particle diameter corresponding to 90 % of the cumulative undersize distribution

��,�
x projected area equivalent diameter of particle i
x maximum Feret diameter of particle i
imax
x minimum Feret diameter of particle i
imin
 ratio of the measured particle diameter to the static particle diameter
4 Principle
4.1 Key components of a dynamic image analyser

Each system designated as dynamic image analyser consists of the following essential key components.

Additionally, some optional components might be used to either enhance the quality of the measurements

or to deal with particular set-up characteristics.
a) Essential
 Illumination
 Particle motion
 Optical system
 Image capture device
 Image analysis
 Conversion to meaningful particle size parameters
 Statistical representation of descriptors
b) Optional
 Particle dispersers
 Particle positioning

A general diagram for dynamic image analysis is shown in Figure 1 & Figure 2. The illumination can be

set-up in a transmitted light arrangement (Figure 1), in a reflection arrangement (Figure 2) or in a

combination of both. In a reflection arrangement a reflecting device, the vessel wall or even the particles

may reflect the light back through the measurement zone as transflected light. The type of lighting has a

great influence on the appearance of the particle images.
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ISO/DIS 13322-2:2019(E)
4 7 8
5 5
9 X
Key
1 dispersed particles 6 acceptable depth of field
2 device for control of particle motion (optional) 7 image capture device
3 measurement zone 8 image analyser
4 light source 9 representation of results
5 optical system

Figure 1 — Flow diagram for typical dynamic image analysis method (transmission set-up)

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ISO/DIS 13322-2:2019(E)
Key
1 dispersed particles 8 image
...