1、 Reference number ISO/IEC TR 29186:2012(E) ISO/IEC 2012TECHNICAL REPORT ISO/IEC TR 29186 First edition 2012-07-15Information technology Office equipment Test method of colour gamut mapping algorithm for office colour softcopy and hardcopy Technologies de linformation quipement de bureau Mthode dessa
2、i des algorithmes de mappage des gammes de couleurs pour images lcran et copies papier ISO/IEC TR 29186:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
3、 or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in 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 We
4、b www.iso.org Published in Switzerland ii ISO/IEC 2012 All rights reservedISO/IEC TR 29186:2012(E) ISO/IEC 2012 All rights reserved iiiContents Page Foreword . 4 Introduction . 5 1 Scope 1 2 Normative references 1 3 Terms and definitions . 1 4 Requirements . 2 4.1 General . 2 4.2 Reference viewing e
5、nvironments for softcopy and hardcopy 2 4.3 Test chart Image processing 4 4.4 Format of test charts . 5 4.5 Experiments . 5 5 Indicating the Use of Test Method of Colour Gamut Mapping Algorithm for Office Colour Printer . 5 5.1 General . 5 5.2 Preparation of samples . 5 5.3 Presentation of the resul
6、t . 6 Annex A (informative) Test Chart Weather 8 Annex B (informative) Test Chart OFFICE GAMUT MAPPING . 9 Annex C (informative) Test Chart False contour chart . 10 Annex D (normative) Test chart Image Processing Workflow . 11 Bibliography 12 ISO/IEC TR 29186:2012(E) iv ISO/IEC 2012 All rights reser
7、vedForeword 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 tec
8、hnical 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 take p
9、art in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare Int
10、ernational Standards. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. In exceptional circumstances, when the joint t
11、echnical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide to publish a Technical Report. A Technical Report is entirely informative in nature and shall be subject to review every five
12、years in the same manner as an International Standard. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC TR 29186 was prepared by Joint
13、 Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 28, Office equipment. ISO/IEC TR 29186:2012(E) ISO/IEC 2012 All rights reserved vIntroduction Gamut mapping is a mapping of the colour-space coordinates of the elements of a source image to the colour- space coordinates of t
14、he elements of a reproduction to compensate for differences in the source and reproduction medium colour gamut capability. A test guideline for evaluating cross-device and cross-media colour image reproduction gamut mapping algorithms (GMAs), desirable for colour scientists and colour equipment manu
15、facturers, has already been published as CIE 156:2004. CIE 156:2004 has been applied and evaluated in various fields. This Technical Report is intended as a supplement to CIE 156:2004 for use with office colour softcopy and hardcopy equipment. Members of the colour management study group in JBMIA ap
16、plied CIE 156:2004 to office colour printers and found it necessary to specify additional information to ensure consistency in colour gamut mapping algorithm evaluation. The information required for use with office colour equipment, in addition to CIE 156:2004, pertains to the output medium, viewing
17、 environments, test charts, test chart image processing parameters and workflow, etc. This experience led to the development of this Technical Report. CIE 156:2004 specifies general principles to be applied when evaluating colour gamut mapping algorithms of various colour imaging equipment. In addit
18、ion to these general principles, equipment-specific detailed descriptions and exceptions are essential. CIE 156:2004 also specifies colour imaging equipment colour gamut mapping algorithm evaluation methods pertinent to photography and graphic arts. Specification of details pertinent to office colou
19、r equipment colour gamut mapping algorithm evaluation is desirable. Without additional information for the office colour equipment application, users of CIE 156:2004 would have to choose details of the evaluation test method by trial and error and would be unlikely to achieve the same result as one
20、another. With the use of this Technical Report, users not only save time and effort, but also obtain test data that is useful for comparison across different test instances. Consistent test methods will facilitate technological improvements in the area of colour gamut mapping algorithms. TECHNICAL R
21、EPORT ISO/IEC TR 29186:2012(E) ISO/IEC 2012 All rights reserved 1Information technology Office equipment Test method of colour gamut mapping algorithm for office colour softcopy and hardcopy IMPORTANT The electronic file of this document contains colours which are considered to be useful for the cor
22、rect understanding of the document. Users should therefore consider printing thisdocument using a colour printer. 1 Scope This Technical Report is a supplement to CIE 156:2004, applicable for use in evaluating the colour gamut mapping algorithms of office colour softcopy and hardcopy equipment. This
23、 Technical Report defines test charts, test chart image processing workflow, media, viewing conditions, measurements, colour spaces and experimental methods, suitable for use with office equipment, which either do not exist in CIE 156:2004 or are different from CIE 156:2004. Colour softcopy may be d
24、isplayed on monitors, incorporating display technologies such as CRT and LCD. Colour hardcopy may be produced by non-impact colour printers, including technologies such as ink jet and electro photography. 2 Normative references The following referenced documents are indispensable for the application
25、 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 156:2004, Guidelines for the Evaluation of Gamut Mapping Algorithms ISO 3664:2009, Graphic technology and photography
26、 Viewing conditions 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 gamut mapping mapping of the colour-space coordinates of the elements of a source image to colour-space coordinates of the elements of a reproduction to compensate for differ
27、ences in the source and output medium colour gamut capability 3.2 colour gamut dynamic range and colour extent, comprising a volume of colour representation capability 3.3 colour gamut boundary surface determined by a colour gamuts extremes ISO/IEC TR 29186:2012(E) 2 ISO/IEC 2012 All rights reserved
28、3.4 gamut boundary descriptor GBD overall way of approximately describing a colour gamut boundary 3.5 veiling glare light, reflected from an imaging medium, that has not been modulated by the means used to produce the image NOTE 1 Veiling glare lightens and reduces the contrast of the darker parts o
29、f an image. NOTE 2 In CIE 122, the veiling glare of a CRT display is referred to as ambient flare. 3.6 viewing flare veiling glare that is observed in a viewing environment but not accounted for in radiometric measurements made using a prescribed measurement geometry NOTE The viewing flare is expres
30、sed as a percentage of the luminance of adapted white. 3.7 image surround characteristics of the field surrounding the image being viewed, filling the field of vision NOTE 1 Adapted from ISO 22028-1. NOTE 2 The region surrounding the stimulus subtending approximately 10 degrees is called background
31、in CIE Standard S 017/E:2011 ILV. 4 Requirements 4.1 General The reproduction intent for the colour reproduction systems in which GMAs will be evaluated in this Technical Specification is defined to be subjective similarity. This subjective similarity intent is one that aims at reproducing a given c
32、olour image so that the reproduction is as close to the original as possible, with no image enhancing intent. Furthermore, the similarity is determined psychophysically. 4.2 Reference viewing environments for softcopy and hardcopy The following reference viewing conditions define the reference viewi
33、ng environment for subjective accuracy experiments. They are based on conditions for appraisal of images displayed on colour monitors as specified in ISO 3664:2009, 4.5 and are based on conditions for practical appraisal of prints as specified in ISO 3664:2009, 4.3 unless otherwise noted. They are a
34、lso based on conditions for appraisal of images displayed on colour monitors and prints as specified in CIE 156:2004, 5.4 (b). 4.2.1 Ambient light source white point Use an ambient light source white point that approximates CIE standard illuminant D50. 4.2.2 Ambient illuminance on monitor for softco
35、py evaluation Use an ambient illuminance on the monitor at the plane of viewing for softcopy evaluation that is less than or equal to 7/10 of Monitor luminance. ISO/IEC TR 29186:2012(E) ISO/IEC 2012 All rights reserved 3Position the source, image being viewed, and observers eyes to minimize the amou
36、nt of light that is specularly reflected toward the eyes of an observer on or near the normal to the centre of the viewing surface. 4.2.3 Ambient illuminance for hardcopy evaluation Use a light source that delivers illumination at the plane of viewing that approximates the CIE standard illuminant D5
37、0. Use the illuminance at the viewing surface of 500 lx 125 lx as specified in ISO 3664:2009 for the practical appraisal of prints. 4.2.4 Monitor diagonal size Use a monitor with a diagonal size greater than or equal to 17 inches. 4.2.5 Monitor white point Select the monitor white point to approxima
38、te that of CIE standard illuminant D65. 4.2.6 Monitor luminance Use an absolute luminance level for the adapted white in the reference viewing environment that is greater than or equal to 80cd/m2, preferably greater than or equal to 160cd/m2. 4.2.7 Required adaptation time Allow users to adapt for e
39、ach softcopy and hardcopy viewing for at least 20sec, preferably use an adaptation time of 120 sec for a full adaptation as in CIE 162:2010, Figure 5. NOTE Before beginning the process of observations, wait at least 10 minutes to adapt to the ambient light. This 10 minutes adaptation time only appli
40、es at the start of the process of observations, and not when looking back and forth between softcopy and hardcopy during the process of observations. 4.2.8 Viewing distance for softcopy evaluation Use a viewing distance for softcopy evaluation that is greater than or equal to the least of the distan
41、ce of distinct vision (25cm) or preferably approximately 1.5 x monitor diagonal size. NOTE Most importantly, ensure that the entire document subtends approximately the 10 degrees of field of view. 4.2.9 Viewing distance for hardcopy evaluation Use a viewing distance for hardcopy evaluation that is g
42、reater than or equal to the least of the distance of distinct vision (25cm) or preferably approximately 1.5 x A4/Letter diagonal size or 54cm. Most importantly, ensure that the entire document subtends approximately the 10 degrees of field of view. 4.2.10 Softcopy image surround luminous reflectance
43、 Use either no image surround or use a softcopy image surround with a luminous reflectance of 20%. 4.2.11 Hardcopy image surround luminous reflectance Use a hardcopy image surround with a luminous reflectance of 20% with or without a paper white border. ISO/IEC TR 29186:2012(E) 4 ISO/IEC 2012 All ri
44、ghts reserved4.2.12 Veiling glare and viewing flare The veiling glare in the reference viewing environment is to be included in the display black point, as would result from measurement of the display from the viewer position in the reference viewing environment. Viewing flare that may result in vie
45、wing conditions different from the reference viewing conditions is not to be included. NOTE When positioning a display in a viewing environment, it is important to arrange the ambient lighting so that specular reflections off the display faceplate, as seen from the viewer position, are avoided. This
46、 can usually be achieved by placing ambient light sources at an angle of at least 45 degrees relative to the normal to the display faceplate, which is assumed to be the viewers direction of gaze. 4.2.13 Measurements Take measurements using the conditions described in CIE 156:2004, Measurement and Ap
47、pendix B recommended measurement procedures for different media. 4.3 Test chart Image processing 4.3.1 Test Charts The test charts of this test method include 5 different images as listed in Table 1. Table 1 Test chart list Test chart Name File format Colour Encoding Availability BEISPIEL Ski TIFF s
48、RGB, ROMMRGB CIE TC 8-03 homepage N7 TIFF sRGB ISO 12640-2:2004 Weather PDF sRGB See Annex A OFFICEGAMUT MAPPING PDF sRGB See Annex B False contour chart TIFF sRGB See Annex C The three test charts in Table 1, such as Weather, OFFICEGAMUT MAPPING and False contour chart, are downloadable at the foll
49、owing address: http:/standards.iso.org/ittf/PubliclyAvailableStandards/SC28_Test_Pages/ For softcopy to hardcopy sample preparation, test charts are processed with the workflow as shown in Annex D. The evaluating gamut mapping algorithms include Hue-angle preserving minimum E*ab clipping and Chroma-dependent sigmoidal lightness mapping and cusp knee scaling as described in CIE 156:2004, 8.1 and 8.2 respectively. NOTE The role of having these two algorithms is to make it possible to reconcile the different interval sca
