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1、 Reference number ISO 21227-1:2003(E) ISO 2003 INTERNATIONAL STANDARD ISO 21227-1 First edition 2003-08-01 Paints and varnishes Evaluation of defects on coated surfaces using optical imaging Part 1: General guidance Peintures et vernis valuation par imagerie optique des dfauts des surfaces revtues P
2、artie 1: Lignes directrices gnrales Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1
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6、w. ISO 2003 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body i
7、n the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2003 All rights reserved Copyright International Organization for Standardization Provided by IH
8、S under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1:2003(E) ISO 2003 All rights reserved iii Contents Page Forewordiv Introduction v 1 Scope1 2 Normative refe
9、rences .1 3 Terms and definitions.1 4 Principle.5 5 Requirements 5 Annex A (informative) Standards for visual assessment of coating defects.8 Bibliography .10 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/997254500
10、1 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1:2003(E) iv ISO 2003 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bod
11、ies). 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
12、 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives,
13、Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted 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 cast
14、ing a vote. 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. ISO 21227-1 was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommi
15、ttee SC 9, General test methods for paints and varnishes. ISO 21227 consists of the following parts, under the general title Paints and varnishes Evaluation of defects on coated surfaces using optical imaging: Part 1: General guidance Part 2: Evaluation procedure for results of multi-impact stone-ch
16、ipping test Part 3: Evaluation procedure for delamination and corrosion around a scribe At the time of publication of this part of ISO 21227, Parts 2 and 3 were in preparation. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Sta
17、ndards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1:2003(E) ISO 2003 All rights reserved v Introduction Conventional ISO test methods used for evaluating surface defects and appearance changes often utilize pic
18、torial standards which depict particular types of surface deterioration and require human visual evaluation. The technology described in the various parts of this International Standard can yield more objective, accurate, quantitative and reproducible results when compared to the human visual evalua
19、tion techniques. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organi
20、zation for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 21227-1:2003(E) ISO 2003 All rights reserved 1 Pai
21、nts and varnishes Evaluation of defects on coated surfaces using optical imaging Part 1: General guidance 1 Scope This part of ISO 21227 gives definitions for and provides guidance in the use of optical imaging systems for the quantitative characterization of defects on coated surfaces that occur af
22、ter exposure in various test methods, e.g. stone chipping, weathering or cross-cut testing. One aim of ISO 21227 is to use optical imaging to reproduce the results of already existing methods for visual assessment. Additionally, optical imaging provides further information which can be used for a mo
23、re detailed evaluation of coating defects. This part of ISO 21227 contains a general introduction in optical-imaging methods and definitions. The performance of individual test methods and requirements for precision are described in other parts of the standard. 2 Normative references The following r
24、eferenced 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 referenced document (including any amendments) applies. CIE Publication No. 17.4:1987, International lighting vocabulary
25、/IEC 60050-845:1987, International Electrotechnical Vocabulary Lighting 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 optical imaging method for acquiring, digitizing, processing and analysing images using optical components and computer sy
26、stems 3.2 illumination application of light to a scene, objects or their surroundings so that they may be seen CIE 17.4:1987/IEC 60050-845:1987 3.2.1 reflection illumination illumination whereby light source and optical sensor are both arranged on the same side of the object Copyright International
27、Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1:2003(E) 2 ISO 2003 All rights reserved 3.2.2 transmission i
28、llumination illumination whereby light source and optical sensor are arranged on opposite sides of the object 3.2.3 bright-field illumination method of image acquisition in which light reflected by the object and light scattered by the object are detected by the optical sensor 3.2.4 dark-field illum
29、ination method of image acquisition in which only light scattered by the object is detected by the optical sensor 3.2.5 directional lighting lighting in which the light on the working plane or on an object is incident predominantly from a particular direction CIE 17.4:1987/IEC 60050-845:1987 3.2.6 d
30、iffused lighting lighting in which the light on the working plane or on an object is not incident predominantly from a particular direction CIE 17.4:1987/IEC 60050-845:1987 3.3 Terms relating to the optical sensor 3.3.1 field of vision area on the object surface which is acquired by the optical sens
31、or 3.3.2 region of interest that part of the original image which is used for image processing and image analysis 3.3.3 objective optical system, usually consisting of one or more lenses, which is used to acquire an image of the field of vision 3.3.4 object distance distance between the first lens o
32、f the objective and an object which gives a sharp image 3.3.5 depth of focus difference between the minimum and maximum object distance 3.4 image acquisition image capture process of creating a two-dimensional original image of an object 3.4.1 original image digitized image taken by the image-acquis
33、ition system, without having carried out any image processing Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license
34、from IHS -,-,- ISO 21227-1:2003(E) ISO 2003 All rights reserved 3 3.4.2 charge-coupled device CCD device that uses a semi-conductive material as an optical sensor NOTE The CCD chip is subdivided into very fine elements, each of which corresponds to a pixel of the digitized image. The CCDs can be arr
35、anged as an array (digital camera) or in a row (line scanner). 3.4.3 scanner device for image acquisition which uses a one-dimensional optical sensor in which CCDs are lined up in a row NOTE The image is built up by line scanning of the surface of an object. 3.4.4 digitization process of converting
36、an analogue image into a digital image NOTE The image is divided into pixels by a grid and each pixel is assigned to one grey level. 3.4.5 pixel smallest image-forming element to which a grey level is assigned 3.4.6 resolution number of pixels per unit length on the surface of an object NOTE If the
37、resolution in the X- and Y-directions is different, both values have to be reported. 3.4.7 grey level shade of grey assigned to a pixel NOTE The shades are usually positive integer values taken from the grey scale. 3.4.8 grey scale series of grey levels between white and black EXAMPLE The 8-bit grey
38、 scale has 28 (= 256) grey levels. Grey level 0 corresponds to black, grey level 255 (the 256th level) to white. 3.4.9 gamma exponent used in the function Y = X where X is the input signal; Y is the output signal; X and Y range from 0 to 1 (0 corresponding to black, 1 to white) 3.4.10 frame grabber
39、device for converting an analogue video signal into an digital original image Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted
40、without license from IHS -,-,- ISO 21227-1:2003(E) 4 ISO 2003 All rights reserved 3.5 image processing software manipulation of the original image in order to prepare for subsequent image analysis NOTE For example, image processing can be used to eliminate mistakes generated during image acquisition
41、 or to reduce image information to the essential. 3.5.1 binary image image in which each pixel is either 0 (black) or 1 (white) 3.5.2 gamma correction modification of the value of gamma, which can be carried out using software or hardware 3.5.3 brightness average grey level of a specified part of th
42、e image 3.5.4 contrast difference between the grey levels of two specified parts of the image 3.5.5 shading correction software method for correcting non-uniformity of the illumination of the object 3.5.6 thresholding reduction of the number of different grey levels of an image, preferably resulting
43、 in a binary image NOTE In order to produce a binary image, each pixel in the grey-scale image is assigned a grey level of 0 or 1, depending whether this pixel has a grey level greater than or less than or equal to a given constant (the threshold). 3.5.7 delineation edge detection method of isolatin
44、g and locating an optical edge in a given digital image 3.6 image analysis reduction of the image information to a set of values which are specific to the application 3.6.1 reference panel specified panel which has already been assessed and therefore has a known rating NOTE It is used to check the r
45、eproducibility and repeatability of the parameter settings. 3.7 image evaluation process of relating the set of values resulting from image analysis to one or more characteristic values via a classification or rating scheme Copyright International Organization for Standardization Provided by IHS und
46、er license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:12:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 21227-1:2003(E) ISO 2003 All rights reserved 5 4 Principle Perception and evaluation of visual information is an outsta
47、nding ability of the human mind. ISO 21227 is intended to imitate and in some cases to exceed this ability by use of digital optical imaging. Before defects on a coated surface can be analysed using optical imaging, an image has to be acquired and transformed into a digital format. An image is acqui
48、red via an image sensor such as a charge-coupled device. In a second step, the subsequent spatial image information is digitized and processed by manipulating the grey levels. Using image analysis, the image information is reduced to a set of values which are specific to the application. In the paint industry, coated panels are generally used for testing. These are exposed