1、BS ISO/IEC 24790:2017 Information technology Office equipment Measurement of image quality attributes for hardcopy output Monochrome text and graphic images BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO/IEC 24790:2017 BRITISH STANDARD National foreword This
2、 British Standard is the UK implementation of ISO/IEC 24790:2017. It supersedes PD ISO/IEC TS 24790:2012 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee IST/3, IT Printers and Cartridges. A list of organizations represented on this committee can be ob
3、tained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 91919 0 ICS 37.100.10 Complia
4、nce with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017. Amendments/corrigenda issued since publication Date Text affectedBS ISO/IEC 24790:2017 Information techn
5、ology Office equipment Measurement of image quality attributes for hardcopy output Monochrome text and graphic images Technologies de linformation quipement de bureau Mesurage des attributs de qualit dimage Texte monochrome et images graphiques INTERNATIONAL STANDARD ISO/IEC 24790 Reference number I
6、SO/IEC 24790:2017(E) First edition 2017-02 ISO/IEC 2017 BS ISO/IEC 24790:2017ii ISO/IEC 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in
7、 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 ISOs member body in the country of the requester. ISO copyright office Ch. de
8、Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO/IEC 24790:2017(E)BS ISO/IEC 24790:2017ISO/IEC 24790:2017(E)Foreword v Introduction vi 1 Scope . 1 2 Normative references 1 3 Terms and definitions . 1 4 Report of resu
9、lts and sampling scheme . 5 4.1 Report of results 5 4.1.1 Test identification information 5 4.1.2 Instrument system . 5 4.1.3 Conformance . 5 4.1.4 Sampling scheme . 5 4.1.5 Results . 5 4.2 Sampling of pages . 6 4.3 Sampling of images . 6 4.3.1 General 6 4.3.2 Discretionary sampling 6 4.3.3 Random s
10、ampling . 7 4.3.4 Whole page sampling . 8 5 Attributes and their measures . 8 5.1 Schema of attributes 8 5.2 Large area graphic image quality attributes . 9 5.2.1 General 9 5.2.2 Large area R maxand R min9 5.2.3 Large area darkness 9 5.2.4 Background darkness .10 5.2.5 Graininess .11 5.2.6 Mottle 13
11、 5.2.7 Background extraneous mark .14 5.2.8 Large area void .15 5.2.9 Banding .16 5.3 Character and line image quality attributes .17 5.3.1 General.17 5.3.2 Character and line image R maxand R min17 5.3.3 Line width .18 5.3.4 Character darkness .18 5.3.5 Blurriness 19 5.3.6 Raggedness 20 5.3.7 Chara
12、cter void .21 5.3.8 Character surround area extraneous mark 22 5.3.9 Character surround area haze .23 6 System conformance 23 6.1 Conformance standard 23 6.2 Instrument .24 6.2.1 OECF conversion .24 6.2.2 MTF compensation .25 6.3 Test objects 26 6.3.1 Specification for production of lines 26 6.3.2 S
13、pecification for production of large images 31 6.3.3 Slanted edge pattern . .34 6.4 Goal values .34 Annex A (normative) Bitmaps for conformance test lines .37 ISO/IEC 2017 All rights reserved iii Contents PageBS ISO/IEC 24790:2017ISO/IEC 24790:2017(E)Annex B (informative) How to use this document .4
14、1 Annex C (normative) Layout of test images for system conformance test 54 Annex D (informative) Method to determine R max , R minand ROI .57 Annex E (informative) Development of system conformance test chart 62 Bibliography .65 iv ISO/IEC 2017 All rights reservedBS ISO/IEC 24790:2017ISO/IEC 24790:2
15、017(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through
16、 technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also ta
17、ke part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. 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 differe
18、nt 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 m
19、ay 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/ p
20、atents). 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 voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information
21、about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: w w w . i s o .org/ iso/ foreword .html. This document was prepared by ISO/IEC JTC 1, Information technology, Subcommittee SC 28, Office equipment. This first edition
22、 of ISO/IEC 24790 cancels and replaces ISO/IEC TS 24790:2012 and ISO/IEC 13660:2001, which have been technically revised. ISO/IEC 2017 All rights reserved vBS ISO/IEC 24790:2017ISO/IEC 24790:2017(E) Introduction This document is designed to help a quality control engineer evaluate the image quality
23、of prints from office imaging systems. In traditional imaging systems (such as ink-on-paper printing), an image is evaluated by comparison to an original or master version of that image. In many electronic imaging systems, however, the image is created digitally within the system. There is no hardco
24、py master and so there can be no evaluation by comparison in the ordinary way. Often, those who operate electronic imaging systems ensure good image quality by controlling the imaging process. They use test targets and reference images to evaluate the performance of the system. If it is not possible
25、 to control image quality by controlling the imaging process and if no test target or reference image is available, we can rely only on direct evaluation of properties of the image itself. To perform intrinsic evaluations of image quality, consider the nature of an image that is an output. An image
26、is some organization of information in space. We assume that these signals have some purpose or are making some attempt at communication. Good image quality means that the image is legible (the organization and information can be interpreted) and that it has a pleasing appearance. Our goals in devel
27、oping this document were to compile a list of image quality attributes that (taken together) correlate to human perception of print quality and to develop measurement methods for these attributes that can be automated and carried out on a simple system. Legibility and appearance have several aspects
28、: detail can be detected easily; image elements are well isolated from the background; the image has a minimum of gross defects; the imaging system has good geometric fidelity. Not all these factors can be covered by evaluation of intrinsic, quantitative image quality attributes. Many of them have a
29、 large psychological or cultural component that is difficult to evaluate. A print made with large optical reduction or one that is out of focus can still have excellent edge quality (and be totally lacking in gross defects, banding, noise, etc.) and yet be illegible. This could occur primarily becau
30、se of the high process gamma (contrast) that is characteristic of many xerographic processes. Thus, the process can produce apparently sharp edges in spite of the loss in resolution. Without a resolution target of some kind, the extent of the resolution loss, and hence legibility, may not be known.
31、The purpose of this document is to present a set of objective, measurable attributes that give some correlation to the perceived quality of an image to a human observer at a standard viewing distance. This document allows a user of printed material to sort samples into several groups, from excellent
32、 to bad. The attributes and methods for their assessment are based on several assumptions: the image represents an attempt at communication; there is uniformity within identifiable image elements; character images, symbols and graphic elements are regular (that is, they are intended to be identical
33、when they have multiple, similar occurrences); samples with extreme gross defects have been screened out.vi ISO/IEC 2017 All rights reservedBS ISO/IEC 24790:2017ISO/IEC 24790:2017(E) This document applies to monochrome images made up of text, graphics and other image objects with two tone levels of
34、a single colour (typically black image on white paper) or halftones, images with more nominal gray levels. This document does not cover continuous tone images, colour images and so on. Image quality measurement can be thought of as divided into diagnostic (high resolution) and visual scale (low reso
35、lution) procedures. Diagnostic measurements typically use precision test targets and instrumentation and are key to much engineering work. The present procedure, by contrast, is limited to phenomena visible to the naked eye and does not permit test patterns. The working group has taken the approach
36、of selecting simple and (in our judgment) effective metrics, rather than attempting to prove that our method of doing a given job will always be the most exact. How will this document actually be implemented? A complete evaluation system has four components: an image capture device, evaluation softw
37、are, application-specific quality standards and sampling plan. The end user may choose to develop all these parts himself or he may choose to purchase one or more components from a commercial supplier. Any equipment capable of gathering data appropriate to these measurements is understood to have a
38、complex instrument function. Rather than attempting to explore the relationship among these instrument functions, the working group has defined reference images and target values for them. If these target values are achieved by an instrument, calibration will be acceptably good. This is not an attem
39、pt to break new ground in image science. It is an attempt to provide suppliers and customers for copies/prints with a practical and objective way to communicate about basic image quality parameters. ISO/IEC 13660 was developed and standardized by the point of view described above. ISO/IEC 13660 is c
40、urrently the only available systematic image quality attribute measurement standard. ISO/IEC 13660 has had a great influence on related industries and image quality measurement instruments based on ISO/IEC 13660 are already marketed. However, due to the limited development time, it was standardized
41、with many issues unresolved and therefore, ISO/IEC 13660 has not been adopted as widely as expected. The main issues are listed as following: a) the test chart and methods for measurement system conformance are only specified for some of character and line attributes. For large area graphic image qu
42、ality attributes, neither test charts nor methods are specified. Eight items of image quality attribute for character and line image and six items of image quality attribute for large area graphic image are defined, and each measuring method is specified. Of the 14 image quality attributes, the conf
43、ormance test method, the conformance test chart and the targeted value for measurement apparatus conformance are specified for only four of the character and line image quality attributes, leaving 10 of the image quality attributes with no conformance specifications; b) physical measures (line width
44、, large area voids) and psychophysical factors (darkness, graininess, etc.) are intermingled and are all defined as image quality attributes; c) the goal values for measurement system conformance are available for only four character and line attributes, and the allowances are very large; d) when on
45、e measures the character and line image quality attributes according to ISO/IEC 13660, the resulting values have large variation and they do not correspond well with subjective evaluations. This document added the following content to ISO/IEC 13660 to resolve the issues which ISO/IEC 13660 had and t
46、o improve the measurement accuracy. a) Banding which is a common image quality defect of the hard copy output in a printer or a copying machine is added as one of the image quality attributes of a large area graphic image. b) Conformance test charts and the goal values for measurement system qualifi
47、cation are specified for three character and line image quality attributes and seven large area graphic image quality attributes. ISO/IEC 2017 All rights reserved viiBS ISO/IEC 24790:2017ISO/IEC 24790:2017(E) c) The fundamental resolution of the scanner for measurement was increased from 600 spi to
48、1 200 spi to reduce the measurement variation. d) Nearly all of the image quality attributes defined in ISO/IEC 13660 have been redefined in ISO/IEC 24790 to eliminate intermingling physical measures and psychophysical factors. e) In order to improve the correspondence between image quality attribut
49、es and subjective evaluations, an image quality attribute measurement evaluation experiment was conducted on seven items (graininess, mottle, banding, line width, character darkness, blurriness and raggedness) of image quality attributes to select prediction algorithms for image quality attributes that have the highest correlation with subjective evaluation. The measurement evaluation experiment was conducted by five countries which includes Japan, U.S.A, China, South Korea and the Net
