1、Electronic display devices Part 2-3: Measurements of optical properties Multi-colour test patterns PD IEC/TR 62977-2-3:2017 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National foreword This Published Document is the UK implementation of IEC/TR 62977-2-3:2017. T
2、he UK participation in its preparation was entrusted to Technical Committee EPL/47, Semiconductors. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are re
3、sponsible for its correct application. The British Standards Institution 2017. Published by BSI Standards Limited 2017 ISBN 978 0 580 93073 7 ICS 31.120; 31.260 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority
4、 of the Standards Policy and Strategy Committee on 31 March 2017. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD IEC/TR 62977-2-3:2017 IEC TR 62977-2-3 Edition 1.0 2017-03 TECHNICAL REPORT Electronic display devices Part 2-3: Measurements of optical propertie
5、s Multi-colour test patterns INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31.120; 31.260 ISBN 978-2-8322-4018-2 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colour inside PD IEC/TR 62977-2
6、-3:2017 2 IEC TR 62977-2-3:2017 IEC 2017 CONTENTS FOREWORD . 3 INTRODUCTION . 5 1 Scope 6 2 Normative references 6 3 Terms, definitions and abbreviated terms 6 3.1 Terms and definitions 6 3.2 Abbreviated terms . 6 4 Colour-managed displays 7 4.1 Legacy displays 7 4.2 Modern displays 7 5 Results 8 6
7、Conclusion 15 Bibliography 16 Figure 1 Legacy model . 7 Figure 2 Example of modern drive models . 8 Figure 3 Example of RGB checkerboard patterns . 9 Figure 4 Example of test pattern with low colour content, where measurement locations are identified by the circles 10 Figure 5 Example of RGB and whi
8、te test pattern 10 Figure 6 Low APL loading series of red, green, blue, and white test patterns . 12 Figure 7 Example signal loading behaviour for an WRGB (top) and RGB (bottom) OLED display 13 Figure 8 Example of a low APL loading test pattern with small box size 14 Figure 9 Example of APL loading
9、profiles of a WRGB OLED display (top) compared to an RGB OLED display . 15 Table 1 Example luminance data for an RGB and WRGB OLED display . 12 Table 2 Scaling the size of the colour boxes in the APL loading pattern relative to the screen dimensions 14 PD IEC/TR 62977-2-3:2017IEC TR 62977-2-3:2017 I
10、EC 2017 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ELECTRONIC DISPLAY DEVICES Part 2-3: Measurements of optical properties Multi-colour test patterns FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotech
11、nical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications
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20、is publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any o
21、r all such patent rights. The main task of IEC technical committees is to prepare International Standards. However, a technical committee may propose the publication of a technical report when it has collected data of a different kind from that which is normally published as an International Standar
22、d, for example “state of the art“. IEC TR 62977-2-3, which is a technical report, has been prepared by IEC technical committee 110: Electronic display devices. The text of this technical report is based on the following documents: Enquiry draft Report on voting 110/781A/DTR 110/800A/RVDTR Full infor
23、mation on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. PD IEC/TR 62977-2-3:2017 4 IEC TR 62977-2-3:2017 IEC 2017 This document has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC
24、 62977 series, published under the general title Electronic display devices, can be found on the IEC website. The committee has decided that the contents of this document will remain unchanged until the stability date indicated on the IEC website under “http:/webstore.iec.ch“ in the data related to
25、the specific document. At this date, the document will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicates that it contains colour
26、s which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. PD IEC/TR 62977-2-3:2017IEC TR 62977-2-3:2017 IEC 2017 5 INTRODUCTION Current display measurement standards mainly use simple test patterns to estimat
27、e the display performance. These test patterns would typically contain only one colour, or a colour with a black background. However, as recent research has shown, modern display electronics can be content-aware, and adjust the display rendering based on the input image content. Therefore, multi-col
28、our test patterns that more closely simulate realistic image content are recommended in order to better represent the display performance. This Technical Report discusses the impact of the display drive electronics and image processing on the display rendering behaviour, and reviews research results
29、 that demonstrate the need for multi-colour test patterns and average picture level loading considerations. PD IEC/TR 62977-2-3:2017 6 IEC TR 62977-2-3:2017 IEC 2017 ELECTRONIC DISPLAY DEVICES Part 2-3: Measurements of optical properties Multi-colour test patterns 1 Scope This part of IEC 62977, whi
30、ch is a Technical Report, reviews the impact of test pattern colour content and image loading on the measured displays photometric and colorimetric performance. Experimental data for several display technologies is presented to demonstrate the need for using a broader range of colours in the test pa
31、tterns, and measuring the display at an image loading level appropriate for the intended application. 2 Normative references There are no normative references in this document. 3 Terms, definitions and abbreviated terms For the purposes of this document, the following terms and definitions apply. IS
32、O and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp 3.1 Terms and definitions 3.1.1 signal pixel smallest encoded picture element
33、 in the input image 3.1.2 pre-gamma average picture level average input level of all signal pixels relative to an equivalent white pixel driven by a digital RGB input Note 1 to entry: Unless otherwise stated, the pre-gamma average picture level (APL) will simply be referred to as average picture lev
34、el in this document. Note 2 to entry: the APL will normally be expressed as a percentage, where a full white screen at maximum drive level would be 100 % APL. 3.2 Abbreviated terms APL average picture level CIE Commission Internationale de LEclairage (International Commission on Illumination) LUT lo
35、ok-up tables OLED organic light emitting diode RGB red, green, and blue sRGB standard RGB colour space as defined in IEC 61966-2-1 WRGB white, red, green, and blue PD IEC/TR 62977-2-3:2017IEC TR 62977-2-3:2017 IEC 2017 7 4 Colour-managed displays 4.1 Legacy displays Early displays had driven electro
36、nics that directly controlled the pixel elements. As illustrated in Figure 1, the independent drive electronics in these legacy displays resulted in a direct correlation between the input signal and the primary colour emitters. The direct link between input signals to pixel output meant that there w
37、as only one unique combination of R, G, and B that gave the desired colour. This simplified that calibration process which ensured that the display had proper colorimetric additive mixing. For example, equal input signal levels to the red, green, and blue channels would have created a proportional g
38、rey level. Standard colour spaces, such as the sRGB colour space (IEC 61966-2-1), utilize this additivity property. Current displays that strive to accurately reproduce the encoded colour information in this colour space also need to exhibit the additive mixing property. Figure 1 Legacy model 4.2 Mo
39、dern displays As colour display technology has advanced over the years, so has the colour management of display devices. Display designers have introduced multi-primary pixel formats, and can apply real-time image processing based on specific pixel values contained in the frame to dynamically change
40、 how the image is rendered. Modern display electronics often include look- up tables (LUTs) as a programmable conversion interface between the input signal and pixel output (see top schematic in Figure 2). The use of LUTs allows the physical primary colours to be abstracted to conceptual primary col
41、orants, where these colorants could be tailored to achieve the desired colour gamut. But the colorimetry of these systems may not necessarily follow colorimetric additive mixing. In addition, as the processing power of the electronics has increased, the image processing can also analyse the upcoming
42、 image frame and dynamically change the LUT for the desired appearance. The use of LUTs has enabled an input signal from only one RGB component to activate more than one primary emitter (see for example the bottom schematic in Figure 2). For multi- primary displays, there may be several combinations
43、 of primary emitters that can produce the desired colour. The calibration of the LUT defines how the input signal will be rendered, which will not necessarily result in the expected colorimetric additive mixing based on the input signals. This lack of additivity can have an impact on how accurately
44、the intended image content is rendered. In addition, the lack of additivity also means that the colour gamut area may not be accurately represented by just measuring the response of the R, G, and B inputs in turn. The colour gamut area may no longer be bounded by the triangle connecting the RGB chro
45、maticity coordinates in the CIE 1931 or 1976 chromaticity diagram (see CIE 15). Given this ambiguity, it is important to test how well the display renders luminance and colour relative to the intent of the input content. If the content is intended for viewing on sRGB displays, then the colour manage
46、ment should be tested to verify that the colours are rendered IEC 3 component input signal Independent drive electronics Display color primaries S1 (R) S2 (G) S3 (B) P1 (R) drive P2 (G) drive P3 (B) drive P1 (R) P2 (G) P3 (B) PD IEC/TR 62977-2-3:2017 8 IEC TR 62977-2-3:2017 IEC 2017 correctly. In ad
47、dition, if the display also employs dynamic colour management, then the performance of the display can depend on the type of test pattern used. A set of colour test patterns have been developed to address these issues, and serve as the recommended patterns that should be used to evaluate displays. T
48、hese patterns are a best effort attempt to create a technology-neutral input signal that uniformly samples the colour gamut and queries the colour-managed response of the display in a fair manner. The value of these colour test patterns is illustrated by comparing them to traditional single-colour b
49、ox patterns. Figure 2 Example of modern drive models 5 Results Prior research on multi-primary projectors demonstrated that some colour-managed systems adapted to the rendered test pattern. The colour management system in some displays would preferentially boost the white luminance/illuminance output on white images. However, this white luminance could not be achieved in more natural colour images. This was demonstrated for a projector by Kelley et al using the set of th
