1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T P.914 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2016) SERIES P: TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Audiovisual quality in multimedia services Display requirements for 3D video quality assess
2、ment Recommendation ITU-T P.914 ITU-T P-SERIES RECOMMENDATIONS TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Voice terminal characteristics Series P.30 P.300 Reference systems Series
3、 P.40 Objective measuring apparatus Series P.50 P.500 Objective electro-acoustical measurements Series P.60 Measurements related to speech loudness Series P.70 Methods for objective and subjective assessment of speech quality Series P.80 P.800 Audiovisual quality in multimedia services Series P.900
4、Transmission performance and QoS aspects of IP end-points Series P.1000 Communications involving vehicles Series P.1100 Models and tools for quality assessment of streamed media Series P.1200 Telemeeting assessment Series P.1300 Statistical analysis, evaluation and reporting guidelines of quality me
5、asurements Series P.1400 Methods for objective and subjective assessment of quality of services other than voice services Series P.1500 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T P.914 (03/2016) i Recommendation ITU-T P.914 Display requirements for 3D video qu
6、ality assessment Summary Recommendation ITU-T P.914 specifies the requirements for the selection of three dimensional (3D) displays when conducting subjective quality assessment experiments. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T P.914 2016-03-15 9 11.1002/1000/1277
7、6 * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T P.914 (03/2016) FOREWORD The International Telecommunication Union (ITU) is
8、 the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing
9、Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
10、 The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Ad
11、ministration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and
12、 compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommenda
13、tion is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claim
14、ed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recomme
15、ndation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, w
16、ithout the prior written permission of ITU. Rec. ITU-T P.914 (03/2016) iii Table of Contents Page 1 Scope . 1 1.1 Applications 1 1.2 Limitations 1 2 References . 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions
17、3 6 3D display requirements . 3 6.1 Display brightness and overall illumination . 3 6.2 Introduction to crosstalk . 3 6.3 Crosstalk measurements . 4 6.4 Crosstalk thresholds 4 7 3D display environment 5 7.1 Impact of overall illumination on visual comfort zone 5 7.2 Distance between display and wall
18、 . 5 7.3 Ambient lighting . 5 Appendix I Perceptual 3D video comparison of various 3D display monitors 6 Appendix II Perceptual 3D video quality of TB and SBS formats with different 3D displays . 7 Appendix III Open questions 9 Bibliography. 10 iv Rec. ITU-T P.914 (03/2016) Introduction Compared to
19、two dimensional (2D) video, several new issues have arisen in three dimensional (3D) video applications and 3D display technologies still face some challenges. It is therefore important to take into account the potential suboptimal rendering of the 3D display when assessing the 3D viewing experience
20、. It is also important to characterize and report properly the 3D display characteristics in the context of subjective testing as this information helps in correctly interpreting subjective results. In particular, three dimensional televisions (3DTVs) exhibit crosstalk to various degrees and can neg
21、atively impact the viewing experience. Crosstalk is a major factor in video quality, visual discomfort and visual fatigue problems. Rec. ITU-T P.914 (03/2016) 1 Recommendation ITU-T P.914 Display requirements for 3D video quality assessment 1 Scope This Recommendation provides guidelines for the sel
22、ection of 3D displays for consistent and repeatable subjective video quality assessment in the context of entertainment content and consumer quality. This Recommendation also provides guidelines for appropriate room environmental constraints that ensure visibility of the stereoscopic effect. 1.1 App
23、lications The applications for the 3D display requirements described in this Recommendation include, but are not limited to: Minimum requirements for 3D display in the context of subjective quality assessment of 3D video; Consistent and repeatable quality assessment of 3D video sequences. The applic
24、able services for this Recommendation include: Cable TV; Streaming video; Internet protocol television (IPTV); Mobile video applications; Interactive video applications. This Recommendation is intended for use with stereoscopic 3D displays, such as: Linearly and circularly polarized glasses for view
25、 separation; Active shutter glasses; Stereoscopic and multiview lenticular array autostereoscopic displays; Stereoscopic and multiview parallax barrier displays; Multiple spectral bandpass filters, a type of enhanced colour separation filters. 1.2 Limitations This Recommendation only applies to vide
26、o quality assessment of coding and transmission error scenarios where the 3D video sequences are moderately to strongly degraded. More stringent display requirements may be needed to accurately assess quality in the presence of nearly lossless quality impairments (e.g., where the quality is nearly t
27、he same as the original 3D video). This Recommendation contains insufficient information for the following applications: While most of the information provided herein applies, additional constraints are required for medical applications; Immersive, virtual reality environments (e.g., gaming, caves,
28、head-mounted displays); Augmented reality. This Recommendation contains insufficient information on overall illumination and display brightness levels for: Mobile devices (e.g., laptops, tablets, phones). The following display technologies are inappropriate for subjective testing, and as such fall o
29、utside the scope of this Recommendation: 2 Rec. ITU-T P.914 (03/2016) Anaglyphic colour separation filters. This Recommendation is not intended for use with holographic displays, light field displays, volumetric displays and stereoscopes (e.g., mobile smartphone 3D). The usage of touchscreens in con
30、junction with 3D displays is outside of the scope of this Recommendation, in particular depth conflicts arise between the depth planes used for displaying contents and the real-world user interaction. User interactions with a 3D touchscreen are outside the scope of this Recommendation (e.g., because
31、 a user fingers enter into the virtual space and they obstruct the eye contact with the stereoscopic reproduction). 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the tim
32、e of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A
33、list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T P.916 Recommendation ITU-T P.916 (2016), Information and guidelines for assessing and mi
34、nimizing visual discomfort and visual fatigue from 3D video. 3 Definitions This Recommendation uses the following term defined elsewhere. 3.1 Terms defined elsewhere 3.1.1 visual comfort zone ITU-T P.916: Visual comfort zone is defined as the depth interval which allows for 3D viewing without the in
35、troduction of visual discomfort. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 crosstalk: The amount of light perceived by the non-intended eye due to incomplete inter-view isolation. 3.2.2 overall illumination: The light coming from all light source
36、s in the room, notably including both the light coming from the display and from the ambient room illumination. This is measured in lux. 3.2.3 view: The video produced by a single camera sensor (i.e., 2D video). 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and ac
37、ronyms: 2D Two Dimensional 3D Three Dimensional 3DTV Three Dimensional Television AVC Advanced Video Coding FPR Film-type Patterned Retarder HRC Hypothetical Reference Conditions Rec. ITU-T P.914 (03/2016) 3 IPTV Internet Protocol Television MOS Mean Opinion Score QP Quantization Parameter SBS Side-
38、By-Side SG Shutter Glasses SRC Source Reference Circuit TB Top-Bottom 5 Conventions The keywords “is required to“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed. The keywords “is recommended“ indi
39、cate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance. The keywords “is prohibited from“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recom
40、mendation is to be claimed. The keywords “can optionally“ indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendors implementation must provide the option and the feature can be optionally enabled by th
41、e network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with this Recommendation. 6 3D display requirements 6.1 Display brightness and overall illumination Display brightness (luminance) is measured as seen through the appropria
42、te 3D glasses (if any). When the measurements are made, the system shall be used in three dimensional television (3DTV) mode. This means, for example in the case of an active shutter glasses (SG) TV, the glasses must be turned on and the measurement system must be synchronized with the shutter cycle
43、. Refer to b-IDMS1 for details on how to measure brightness for various types of displays. 6.2 Introduction to crosstalk Crosstalk is the amount of light perceived by the non-intended eye due to incomplete inter-view isolation. In the context of subjective quality assessment of 3D video, a suitable
44、3D display must be selected such that the display does not affect the reliability and reproducibility of subjective results. However, crosstalk is a major contributor to quality loss and visual discomfort on stereoscopic displays. It can therefore greatly impact the quality of experience in the view
45、ing of stereoscopic 3D content and the results of subjective quality assessment. To achieve consistent results in 3D video quality assessment, it is important to understand the maximum amount of allowable display crosstalk. Subjective testing requires measurement or characterization means to adequat
46、ely select display equipment to conduct such subjective testing in a reliable and repeatable manner. Several works in the literature and works presented to the Video Quality Experts Group have shown that obtaining objective physical measurements of 3D displays to characterize their crosstalk is not
47、straightforward and repeatability of results is still an issue to be solved. There are many parameters 4 Rec. ITU-T P.914 (03/2016) (e.g., distance, angle, characteristics of the measurement instruments) that make physical measurements difficult and many aspects (e.g., non-uniformity, spatial/tempor
48、al variation, anti-crosstalk mechanisms) that make crosstalk difficult to represent as a single value. 6.3 Crosstalk measurements b-IDMS1 provides means of measuring crosstalk with respect to different display technologies. 6.3.1 Grey-to-grey crosstalk Crosstalk is not necessarily only due to leakag
49、e of unintended white image/level onto intended black image/level, but may also be due to other grey-to-grey configurations (other grey-to-grey configurations may produce perceivable/visible crosstalk). The selection of a 3D display for the subjective quality assessment of 3D content should not be based only on the measure of crosstalk using the leakage of light signals from the open to the blocked channel using a white image as the open channel signal and a black image as blocked channel signal, but should also consider the
