BS ISO 13322-2-2006 Particle size analysis - Image analysis methods - Dynamic image analysis methods《粒度分析 图像分析法 静态图像分析法》.pdf

1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Part 2: Dynamic image analysis methodsICS 19.120Particle size analysis Image analysis methods BRITI

2、SH STANDARDBS ISO 13322-2:2006BS ISO 13322-2:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2006 BSI 2006ISBN 0 580 49696 1Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its corre

3、ct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 13322-2:2006.The UK participation in its preparation was entrusted to Technical Committee LBI/37, Sieves, sc

4、reens and particle sizing. A list of organizations represented on LBI/37 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 13322-2:2006(E)INTERNATIONAL STANDARD ISO13322-2First edition2006-11-01Particle size

5、 analysis Image analysis methods Part 2: Dynamic image analysis methods Analyse granulomtrique Mthodes par analyse dimages Partie 2: Mthodes par analyse dimages dynamiques BS ISO 13322-2:2006ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms, definitions an

6、d symbols 1 3.1 Terms and definitions. 1 3.2 Symbols . 2 4 Principle. 3 4.1 General. 3 4.2 Particle motion 4 4.3 Particle positioning. 4 5 Operational procedures . 5 5.1 General. 5 5.2 Still image resolution 5 5.3 Calibration and traceability 6 5.4 Size classes and magnification. 6 5.5 Particle edge

7、s 6 5.6 Measurements. 7 6 Sample preparation 7 7 Sample and measurement variability . 7 Annex A (informative) Particle velocity and exposure time recommended. 8 Annex B (informative) Maximum particle size recommended . 11 Annex C (informative) Typical examples of sample feed and image capture system

8、s 16 Bibliography . 24 BS ISO 13322-2:2006iv 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 memb

9、er 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 Ele

10、ctrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adop

11、ted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of pate

12、nt rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 13322-2 was prepared by Technical Committee ISO/TC 24, Sieves, sieving and other sizing methods, Subcommittee SC 4, Sizing by methods other than sieving. ISO 13322 consists of the following parts, under t

13、he general title Particle size analysis Image analysis methods: Part 1: Static image analysis methods Part 2: Dynamic image analysis methods BS ISO 13322-2:2006vIntroduction The purpose of this part of ISO 13322 is to provide guidance for measuring and describing particle size distribution, using im

14、age 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 severa

15、l image capture methods. Some typical methods are described in this part of ISO 13322. BS ISO 13322-2:2006blank1Particle size analysis Image analysis methods Part 2: Dynamic image analysis methods 1 Scope This part of ISO 13322 describes methods for controlling the position of moving particles in a

16、liquid or gas and on a conveyor, as well as the image capture and image analysis of the particles. These methods are used to measure the particle sizes and their distributions, the particles being appropriately dispersed in the liquid or gas medium or on the conveyor. The practical limitations of th

17、e derived particle size are addressed when using this part of ISO 13322. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the reference

18、d document (including any amendments) applies. ISO 13322-1:2004, Particle size analysis Image analysis methods Part 1: Static image analysis methods 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 flow-cel

19、l measurement cell inside which the fluid-particle mixture flows 3.1.2 orifice tube tube with an aperture through which a stream of fluid with dispersed particles flows 3.1.3 sheath flow clean fluid flow surrounding particle-laden fluid for directing particles into a specific measurement zone 3.1.4

20、particle illumination continuous illumination for image capture device with an electronic exposure time controller, or illumination of short duration for synchronized image capture device BS ISO 13322-2:20062 3.1.5 measurement volume volume in which particles are measured by an image analyser 3.1.6

21、depth of field region where the sharpness of the edges of the images reaches the pre-set optimum 3.1.7 image capture device matrix camera or line camera 3.2 Symbols a moving distance of a particle during time t Aiprojected area of particle i b measured diameter of binary image t exposure time v part

22、icle velocity x diameter of particle xAiprojected area equivalent diameter of particle i ximaxmaximum Feret diameter of particle i ximinminimum Feret diameter of particle i ratio of the measured particle diameter to the static particle diameter BS ISO 13322-2:200634 Principle 4.1 General A general d

23、iagram for dynamic image analysis is shown in Figure 1. Key 1 dispersed particles 2 device for control of particle motion 3 measurement volume 4 light source 5 optical system 6 depth of field 7 image capture device 8 image analyser 9 display Figure 1 Flow diagram for typical dynamic image analysis m

24、ethod BS ISO 13322-2:20064 4.2 Particle motion Moving particles can be introduced into the measurement volume by three means: a) particle motion in a moving fluid (e.g. particles in suspension, in an aerosol, in a duct, in an air jet, in a sheath flow, in turbulent flow or in a push-pull flow regime

25、); b) particle motion in a still fluid, i.e. in an injection or free-falling system, where particles are intentionally moved by an external force (e.g. gravity, electrostatic charge); c) particle motion with a moving substrate, where particles are on the moving substrate (e.g. conveyor belt). 4.3 Pa

26、rticle positioning Particles are introduced into the measurement volume and an image is taken when particles reach the object plane. The depth of the measurement volume is determined by the depth of field of the optical system used. Figure 2 shows an example of measurement volume. Key 1 light source

27、 2 camera 3 measurement volume Figure 2 Example of measurement volume The direction of observation (e.g. parallel or perpendicular) of the particles affects the interpretation of particle size and shape, as shown in Figure 3. However, this part of ISO 13322 is not concerned with the influence of par

28、ticle shape on the overall measurement. BS ISO 13322-2:20065Key 1 measurement volume parallel to particle motion 2 measurement volume perpendicular to particle motion Figure 3 Particle movement and direction of observation The focus of the image capture equipment shall be adjusted so as to acquire t

29、he exact image of the particles moving in the fluid. There are two recommended ways to achieve this: a) by controlling the position of the moving particles so that they pass only within the measurement volume of the image capture equipment; b) by illuminating the particles for a short time period (e

30、.g. by flash light) or capturing the image of the moving particles when they pass through the measurement volume of the image capture equipment. 5 Operational procedures 5.1 General Modern image analysers usually have algorithms to enhance the quality of the image prior to analysis. It is acceptable

31、 to use enhancement algorithms provided that the measured results are traceable back to the original image. 5.2 Still image resolution The resolution of an image captured by a dynamic image analysis system depends not only on the optical system (lens magnification and camera resolution) but also on

32、the lighting system and the velocity of the particles. BS ISO 13322-2:20066 When a spherical particle of diameter x moves at a velocity v, the centre of the projected area of the particle moves a distance a during a time t, where t is either the strobe light emission time or camera shutter opening t

33、ime (see Figure A.1), i.e. avt= (1) Without appropriate grey level handling, a shall not exceed either 0,5 pixel or x (2 1) pixel, where is the ratio of the measured particle diameter to the static particle diameter. Grey level handling between pixel level and background level should ensure that the

34、 measured diameter of binary image b equals the diameter, x, of the static particle. The total system resolution should be determined based on the particle size distribution and the desired confidence limits (see ISO 13322-1). 5.3 Calibration and traceability The equipment shall be calibrated to con

35、vert pixels into SI length units (e.g. nanometres, micrometres, millimetres) for the final results. The calibration procedure shall include verification of the uniformity of the field of view. An essential requirement of the calibration procedure is that all measurements shall be traceable back to t

36、he standard metre. This can be achieved by calibration of the image analysis equipment with a certified standard stage micrometre. Movement of particles during the capture of particle images, especially for smaller particles, may introduce serious error in determining particle sizes. It is therefore

37、 recommended that the whole system be verified with a standard reference material under motion. The calibration particles shall be selected to include the dynamic range of the entire system. It is recommended to calibrate with three sizes of certified particles, i.e. with values near the maximum, mi

38、d-point and minimum particle sizes to be measured with the system. 5.4 Size classes and magnification The theoretical limit for resolution of objects by size using image analysis is 1 pixel, and counts should be stored particle by particle, with the maximum resolution of 1 pixel. However, it is nece

39、ssary to define size classes for the final reporting of the result, which is a function of the total number of particles, the dynamic range and the number of pixels included in the smallest considered objects. It is recommended that pixel size be converted to actual size prior to any reporting of si

40、ze for quantitative analysis. For a system in which not all the particles are measured, large particles may often be positioned on an edge of the image frame. Therefore, the magnification should be selected so that the maximum diameter of the largest particle does not exceed one-third of a shorter s

41、ide of a rectangular image frame of the measuring area (see Annex B). It is strongly recommended to address within the report any errors resulting from the loss of information of larger particles positioned at the edge of an image frame. Optical resolution, where applicable, is normally better than

42、electronic resolution. 5.5 Particle edges In an image, the particle edge shall be defined by a suitable threshold level. The technique for doing this depends on the sophistication of the image analysis equipment. It is strongly recommended that the threshold level be adjusted by comparing the proces

43、sed binary images with the original grey images, in order to ensure that they are a reliable representation of the original grey images. BS ISO 13322-2:200675.6 Measurements The measurement of the perimeter of a particle is heavily dependent on the image analysis system used. It is recommended that

44、the primary measurements are: a) the projected area of each particle in pixels (Ai), b) the longest dimension of each particle in pixels (maximum Feret diameter, ximax), and c) the shortest dimension of each particle in pixels (minimum Feret diameter, ximin), thus allowing the definition of a shape

45、factor with the greatest discrimination. The projected area of each particle can be converted to the area equivalent circular diameter, xAi. 4iAiAx =(2) 6 Sample preparation The number of particles in the dispersion medium shall be controlled so that overlapping images of particles are not generated

46、. 7 Sample and measurement variability The measurement of the total number of particles or the total particle number count is possible under certain conditions. Such methods should ensure that no particles are lost or counted more than once. The minimum number of particles to be counted shall be bas

47、ed upon the particle size distribution and the desired confidence limits (see ISO 13322-1). To increase the confidence in the measurements, statistical parameters such as the mean diameter and standard deviation for a group of measurements can be calculated. Annex C provides typical examples of samp

48、le feed and image capture systems. BS ISO 13322-2:20068 Annex A (informative) Particle velocity and exposure time recommended Special precautions are required when measuring small particles in motion by dynamic image analysis. When a spherical particle of diameter x pix moves at a velocity v pix/s a

49、nd the exposure time is t s, the centre of area of the particle moves the distance a pix during this period, i.e. avt= (A.1) The observed diameter of the particle b pix in the direction of motion is between (x + a) and (x a), depending on the threshold level used (see Figure A.1). Consequently, when the image of a moving spherical particle is captured as a grey image and then converted into a binary image with a given threshold level, the shape appears to be a prolonged ellipsoid rather than circ