ISO/IEC JTC 1/SC 29 N 16019

Transcription

1 ISO/IEC JTC 1/SC 29 N ISO/IEC JTC 1/SC 29 Coding of audio, picture, multimedia and hypermedia information Secretariat: JISC (Japan) Document type: Title: Status: Text for PDAM ballot or comment Text of ISO/IEC :2015/PDAM 1: Information technology -- Advanced image coding and evaluation methodologies -- Part 2: Evaluation Procedure for nearly lossless coding, AMENDMENT 1: Parameters for nearly lossless coding of high dynamic range media [SC 29/WG 1 N 72026] Text of PDAM agreed at the 72nd SC 29/WG 1 Meeting (Ref. SC 29 N 15906, 39). [Requested action: For ballot by SC 29 P-members] Date of document: Source: ISO/IEC JTC 1/SC 29/WG 1 Expected action: VOTE Action due date: No. of pages: 11 of secretary: Committee URL: sc29-sec@itscj.ipsj.or.jp

2 ISO/IEC 2016 All rights reserved ISO/IEC JTC 1/SC 29 N xxxxx Date: ISO/IEC :2015/PDAM 1 ISO/IEC JTC 1/SC 29/WG 1 Secretariat: JISC Information technology Advanced image coding and evaluation Part 2: Evaluation procedure parameters for nearly losssless coding of high dynamic range media Warning This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an International Standard. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation. Document type: International Standard Document subtype: Amendment Document stage: (30) Committee Document language: E D:\temp\macroserver\DOCX2PDFISOTC\DOCX2PDFISOTC.lliadmin@SRVWEB100_219\ _1.doc S TD Version 2.1c2

3 Copyright notice This ISO document is a working draft or committee draft and is copyright-protected by ISO. While the reproduction of working drafts or committee drafts in any form for use by participants in the ISO standards development process is permitted without prior permission from ISO, neither this document nor any extract from it may be reproduced, stored or transmitted in any form for any other purpose without prior written permission from ISO. Requests for permission to reproduce this document for the purpose of selling it should be addressed as shown below or to ISO's member body in the country of the requester: [Indicate the full address, telephone number, fax number, telex number, and electronic mail address, as appropriate, of the Copyright Manger of the ISO member body responsible for the secretariat of the TC or SC within the framework of which the working document has been prepared.] Reproduction for sales purposes may be subject to royalty payments or a licensing agreement. Violators may be prosecuted. ii ISO/IEC 2016 All rights reserved

4 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 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 take part 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 International 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. 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. Amendment 1 to ISO/IEC :2015 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information Technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information. ISO/IEC 2016 All rights reserved iii

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6 Information technology Advanced image coding and evaluation Part 2: Evaluation procedure parameters for nearly losssless coding of high dynamic range media 1 Amendment Scope This Technical Specification normalizes evaluation and grading of a light coding system used for displays and display systems, but is independent of the display technology. This amendment extends evaluation of coding to elements sensitive to high dynamic range (HDR) media, including the content preparation, image viewing conditions and control of displays. The normalized methods include whether an observer can distinguish between an uncompressed reference and the reconstructed image sequence to a similar pre-determined and statistically meaningful level. This amendment allows a second viewing distance based on expert feedback and an industry preference to view large HDR-capable displays at approximately 1.5 times the screen height for ultra-high resolution displays. Below this line begin all amendment clauses and text. 1 Scope This amendment contains no changes to the Scope clause. 2 Normative references This amendment contains no changes to the Normative references clause. 3 Terms and Definitions This amendment adds the following terms and definitions clause. 3.1 high dynamic range an image or image sequence format range conveying a larger range of perceptible shadow and highlight detail, with sufficient precision and acceptable artefacts including sufficient separation of diffuse white and specular highlights ISO/IEC 2016 All rights reserved 1

7 3.2 standard dynamic range an image or image sequence format conveying typical colour volume and rendering characteristics similar to those specified in Recommendation ITU-R BT.709 or IEC (srgb) 3.3 wide color gamut an image or image sequence format rendered a colour range larger than standard dynamic range systems, typically > 75% of the human visible spectrum 4 Symbols (and abbreviated terms) This amendment adds the following abbreviations: HDR SDR high dynamic range standard dynamic range 5 Test methods Editor's note: Clause 5 contains several sub-clauses with amended test. Only the sub-clauses listed below contain changes. Red text indicates an addition. Change the title of clause to: Standard dynamic range lighting and display calibration Viewing distance Add the row and the table footnote to Table 2. Table 2 Viewing distance versus display size and resolution Table Condition PPD a D b cm Viewing distance for SDR evaluation 30 Viewing distance for HDR evaluation 60 d D equals the larger of the value in the following equation or 12cm c D H RES W 1 tan( ) PPD 2 ISO/IEC 2016 All rights reserved

8 a The experiment requires a consistent display orientation to be maintained and mobile display may have a different width and pixel resolution in landscape versus portrait orientation. PPD is calculated for each orientation. Detailed work on computer displays and mobile devices tends to be closer than for general entertainment, e.g., television, and requires evaluation with a more aggressive PPD than would be the case for Snellen acuity (30 cycles/degree or PPD = 60) b c d W is the screen width (cm) and HRES is the number of pixels across the display horizontally as viewed by the observer. The minimum focusing distance for normal vision is predetermined as 12 cm by this Technical Specification. Snellen distance viewing distance may be used for SDR evaluation when the evaluator determines the display (television) is large enough to cause observer discomfort High dynamic range lighting and display calibration Viewing conditions shall be consistent with ISO 3664 and ISO viewing condition for images displayed on high brightness displays, such as, televisions or. Exceptions include: a) The luminance of the white displayed on the monitor shall be > 300 cd/m 2. b) Displays that do not contain calibration tables should be avoided. However, if used, this specification recommends televisions and monitors with colour, contrast and tint adjustment controls so that the light output can be characterized with a spectrometer [ref needed] and colour calibration completed using any of a number of procedures noted by the monitor or TV maker. Note deviations in the test report. Record maximum luminance of the display used in the procedure using a 2% white centre and a black field. c) The colour of surrounding walls and ceilings do not require a specific colour but shall not cause distracting reflections that may affect the vision of the observer. An appropriate viewing booth is optionally desirable. d) The display monitor shall render at least the number of bits per component present in the tested images. 5.5 Viewing time Add the following paragraph to the end of Clause 5.5: The image viewing time may be extended to 10 s if the evaluator finds that the test display shows temporal dithering effects, which tend to distract observers from clearly identifying dithering from scintillations caused by image interleaving employed by the protocol in Annex B. Add the following Annex G. Note that red text is omitted, all the text in Annex G is an addition. ISO/IEC 2016 All rights reserved 3

9 Annex G (informative) HDR image preparation G.1 Colour space The following guidance is offered for HDR image or image sequence preparation: 1. Content should be mastered to the same or lower maximum luminance of the display to be used in order to minimize effects and modifications of colours by display tone mapping functions. 2. Determine a suitable target average brightness range and stabilize salient image content to the target brightness range. 3. Document in the test report and map content into the HDR colour space to be testing with a coding system for the duration of any one test session. Known and useful colour spaces are in Table G.1. CS 1 CS 2 CS 3 CS 4 CS 5 CS 6 Table G.1 Colour space identification srgb / Rec ITU-R BT.709 Adobe RGB SMPTE RP (P3) ITU-R BT.2020 Linear User specified G.2 Electro-optical Transfer Function 1) Document and ensure content uses an electro-optical transfer function to be tested with a coding system for the duration of any one test session. Known and useful EOTF's are shown in Table G.2. EOTF 1 Table A.2 EOTF identification Rec. ITU-R BT.1886 EOTF 2 SMPTE ST 2084 EOTF 3 EOTF 4 EOTF 5 BBC WHP 283 (HLG) Linear User specified 4 ISO/IEC 2016 All rights reserved

10 2) Document and map decompressed content to the display color space, if different than used for input to the coding system. Refer to the table in sub-clause 3 for known colour spaces 3) Document and ensure content uses an electro-optical transfer function compatible for the rendering display Refer to sub-clause 4 to choose an EOTF for transmission to the display: 4) Ensure that average light level does not change undergo dramatic change within a test sequence. Trial duration must be longer than display s temporal response window. 5) During between-trial intervals, use a screen with similar average luminance as test materials, recommended at < 25% grey level. 6) Characterize any local backlighting of the display to avoid or mask significant display non uniformity, such as, halos. 7) Specify static metadata for each image in a test sequence to properly trigger display responsiveness in its HDR mode, if used. G.3 HDR software processed workflow option A This workflow is available for testing when the experimenter either has little control over or cannot sufficiently disable HDR tone mapping and other hardware processing in the display unit that may interfere with codec evaluation. The Option A workflow bypasses HDR processing in the display and relies entirely on the experimenter's image or image sequence preparation prior to and after coding. Error! Reference source not found. depicts the recommended workflow to process HDR images and image sequence for coding system evaluation. Figure A.1 Display-independent HDR workflow ISO/IEC 2016 All rights reserved 5

11 G.4 HDR display hardware processed workflow option B This workflow is available for testing when the experimenter has access to a display with transparent HDR processing, well-controlled and known with no tone mapping and other hardware processing in the display unit that may interfere with codec evaluation. The Option B workflow relies on the HDR processing in the display, correct EOTF application and relies entirely on the experimenter's image or image sequence with correct formatting that may include static metadata. Error! Reference source not found. depicts the recommended workflow to process HDR images and image sequence for coding system evaluation. Figure G.2 Production test monitor HDR workflow 6 ISO/IEC 2016 All rights reserved

12 Bibliography This amendment adds the following bibliographic references: [1] IEC , Colour management Default RGB colour space srgb, [2] Recommendation ITU-R BT.709, Parameter values for the HDTV standards for production and international programme exchange, [3] SMPTE ST :2015, Content-Dependent Metadata for Color Volume Transformation of High Luminance and Wide Color Gamut Images [4] SMPTE ST 2086:2014, Mastering Display Color Volume Metadata Supporting High Luminance and Wide Color Gamut Images ISO/IEC 2016 All rights reserved 7