1、BSI Standards Publication BS ISO/IEC 18477-6:2016 Information technology Scalable compression and coding of continuous-tone still images Part 6: IDR Integer CodingBS ISO/IEC 18477-6:2016 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO/IEC 18477-6:2016. The UK
2、 participation in its preparation was entrusted to Technical Committee IST/37, Coding of picture, audio, multimedia and hypermedia information. 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 nece
3、ssary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 87699 8 ICS 35.040 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard
4、 was published under the authority of the Standards Policy and Strategy Committee on 29 February 2016. Amendments/corrigenda issued since publication Date T e x t a f f e c t e dBS ISO/IEC 18477-6:2016 Information technology Scalable compression and coding of continuous-tone still images Part 6: IDR
5、 Integer Coding Technologies de linformation Compression chelonnable et codage dimages plates en ton continu Partie 6: Codage de nombre entier par IDR INTERNATIONAL STANDARD ISO/IEC 18477-6 Reference number ISO/IEC 18477-6:2016(E) First edition 2016-02-01 ISO/IEC 2016 BS ISO/IEC 18477-6:2016ii ISO/I
6、EC 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posti
7、ng 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 Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +4
8、1 22 749 09 47 copyrightiso.org www.iso.org ISO/IEC 18477-6:2016(E)BS ISO/IEC 18477-6:2016ISO/IEC 18477-6:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions, abbr e viat ed t erms, and s ymbols . 1 3.1 Terms and definitions . 1 3.2 Symbols . 6 3.3 Abbrevi
9、ated terms . 7 4 Conventions . 7 4.1 Conformance language . 7 4.2 Operators . 8 4.2.1 Arithmetic operators 8 4.2.2 Logical operators . 8 4.2.3 Relational operators . 8 4.2.4 Precedence order of operators 8 4.2.5 Mathematical functions . 9 5 General 9 5.1 High level overview on JPEG XT ISO/IEC 18477-
10、6 9 5.2 Profiles 11 5.3 Encoder requirements .11 5.4 Decoder requirements.11 Annex A (normative) Encoding and decoding process .13 Annex B (normative) Boxes .17 Annex C (normative) Multi-component decorrelation .24 Annex D (normative) Entr op y c oding of r efinement data .28 Annex E (normative) Pr
11、ofiles 33 Bibliography .34 ISO/IEC 2016 All rights reserved iii Contents PageBS ISO/IEC 18477-6:2016ISO/IEC 18477-6:2016(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardizat
12、ion. 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
13、 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. The procedures used to develop this document and
14、those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (se
15、e www.iso.org/directives). 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. Details of any patent rights identified during the development of
16、the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). 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 meaning of ISO specific
17、terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/IEC JTC 1, Information tec
18、hnology, SC 29, Coding of audio, picture, multimedia and hypermedia information. ISO/IEC 18477 contains the following parts under the general title Information technology Scalable compression and coding of continuous-tone still images: Part 1: Scalable compression and coding of continuous-tone still
19、 images Part 2: Extensions for high dynamic range images Part 3: Box file format Part 6: IDR Integer Coding Part 7: HDR Floating-Point Coding Part 8: Lossless and Near-lossless Coding Part 9: Alpha Channel Coding The following parts are under preparation: Part 4: Conformance testing Part 5: Referenc
20、e softwareiv ISO/IEC 2016 All rights reservedBS ISO/IEC 18477-6:2016ISO/IEC 18477-6:2016(E) Introduction This part of ISO/IEC 18477 specifies a coded codestream format for storage of continuous-tone high and low dynamic range photographic content. JPEG XT part 6 is a scalable image coding system sup
21、porting multiple component images consisting of integer samples of a bit precision between 9 and 16 bits. The format itself is based on the Box Based format specified in ISO/IEC 18477-3, which ensures that legacy applications conforming to Rec. ITU-T T.81 | ISO/IEC 10918-1 are able to reconstruct a
22、lower quality, low dynamic range, eight bits per sample version of the image. Today, the most widely used digital photography format, a minimal implementation of JPEG (specified in ITU Recommendation T.81 | ISO/IEC 10918-1), uses a bit depth of 8; each of the three channels that together compose an
23、image pixel is represented by 8 bits, providing 256 representable values per channel. For more demanding applications, it is not uncommon to use a bit depth of 16, providing 65 536 representable values to describe each channel within a pixel, resulting on over 2,8 10 14representable colour values. M
24、ost common photo and image formats use an 8-bit or 16-bit unsigned integer value to represent some function of the intensity of each colour channel. While it might be theoretically possible to agree on one method for assigning specific numerical values to real world colours, doing so is not practica
25、l. Since any specific device has its own limited range for colour reproduction, the devices range may be a small portion of the agreed-upon universal colour range. As a result, such an approach is an extremely inefficient use of the available numerical values, especially when using only 8 bits (or 2
26、56 unique values) per channel. To represent pixel values as efficiently as possible, devices use a numeric encoding optimized for their own range of possible colours or gamut. JPEG XT is primarily designed to provide coded data containing intermediate dynamic range and wide colour gamut content whil
27、e simultaneously providing 8 bits per pixel low dynamic range images using tools defined in ISO/IEC 18477-1, which is itself a subset of Rec. ITU-T T.81 | ISO/IEC 10918-1. The goal is to provide a backwards compatible coding specification that allows legacy applications and existing toolchains to co
28、ntinue to operate on codestreams conforming to this part of ISO/IEC 18477. JPEG XT has been designed to be backwards compatible to legacy applications while at the same time having a small coding complexity; JPEG XT uses, whenever possible, functional blocks of Rec. ITU-T T.81 | ISO/IEC 10918-1 to e
29、xtend the functionality of the legacy JPEG Coding System. It is optimized for storage and transmission of intermediate dynamic range and wide colour gamut images while also enabling low-complexity encoder and decoder implementations. This part of ISO/IEC 18477 is an extension of ISO/IEC 18477-1, a c
30、ompression system for continuous tone digital still images which is backwards compatible with Rec. ITU-T T.81 | ISO/IEC 10918-1. That is, legacy applications conforming to Rec. ITU-T T.81 | ISO/IEC 10918-1 will be able to reconstruct streams generated by an encoder conforming to this part of ISO/IEC
31、 18477, though will possibly not be able to reconstruct such streams in full dynamic range, full quality or other features defined in this Recommendation| International Standard. This part of ISO/IEC 18477 is itself based on ISO/IEC 18477-3 which defines a box-based file format similar to other JPEG
32、 standards. The aim of this part of ISO/IEC 18477 is to provide a migration path for legacy applications to support, potentially in a limited way, coding of intermediate dynamic range images, that is images represented by sample values requiring 9 to 16 bits precision. While the legacy Rec. ITU-T T.
33、81 | ISO/IEC 10918-1 already defines a coding mode for 12 bit sample precision, images encoded in this mode cannot be decoded by applications implementing only the 8 bit mode. Unlike the legacy standard, this part of ISO/IEC 18477 defines a scalable coding engine supporting all bit depths between 9
34、and 16 bits per sample while also staying compatible with legacy applications. Such applications will continue to work, but will only able to reconstruct an 8 bit standard low dynamic range (LDR) version of the full image contained in the codestream. This part of ISO/IEC 18477 specifies a coded file
35、 format, referred to as JPEG XT, which is designed primarily for storage and interchange of continuous-tone photographic content. ISO/IEC 2016 All rights reserved vBS ISO/IEC 18477-6:2016BS ISO/IEC 18477-6:2016Information technology Scalable compression and coding of continuous-tone still images Par
36、t 6: IDR Integer Coding 1 Scope This part of ISO/IEC 18477 specifies a coding format, referred to as JPEG XT, which is designed primarily for continuous-tone photographic content. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are
37、 indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 18477-1:2015, Information technology Scalable compression and coding of continuous-tone still im
38、ages Part 1: Scalable compression and coding of continuous-tone still images ISO/IEC 18477-3:2015, Information technology Scalable compression and coding of continuous-tone still images Part 3: Box-based file format Rec. ITU-T T.81 | ISO/IEC 10918-1, Information technology Digital compression and co
39、ding of continuous tone still images Requirements and guidelines Rec. ITU-T BT.601, Studio encoding parameters of digital television for standard 4:3 and wide screen 16:9 aspect ratios 3 T erms a nd definiti ons, abbr e viat ed t erms, and s ymbols 3.1 T erms and definiti ons For the purposes of thi
40、s document, the following definitions apply. 3.1.1 A C c o e f f i c i e n t any DCT coefficient for which the frequency is not zero in at least one dimension 3.1.2 ASCII encoding encoding of text characters and text strings according to ISO/IEC 10646-1 3.1.3 base decoding path process of decoding l
41、egacy codestream and refinement data to the base image, jointly with all further steps until residual data is added to the values obtained from the residual codestream 3.1.4 base image collection of sample values obtained by entropy decoding the DCT coefficients of the legacy codestream and the refi
42、nement codestream, and inversely DCT transforming them jointly INTERNATIONAL ST ANDARD ISO/IEC 18477-6:2016(E) ISO/IEC 2016 All rights reserved 1BS ISO/IEC 18477-6:2016ISO/IEC 18477-6:2016(E) 3.1.5 binary decision choice between two alternatives 3.1.6 bitstream partially encoded or decoded sequence
43、of bits comprising an entropy-coded segment 3.1.7 block 8 8 array of samples or an 8 8 array of DCT coefficient values of one component 3.1.8 box structured collection of data describing the image or the image decoding process embedded into one or multiple APP 11marker segments Note 1 to entry: See
44、ISO/IEC 18477-3:2015, Annex B for the definition of boxes. 3.1.9 byte group of 8 bits 3.1.10 coder embodiment of a coding process 3.1.11 coding encoding or decoding 3.1.12 coding model procedure used to convert input data into symbols to be coded 3.1.13 (coding) process general term for referring to
45、 an encoding process, a decoding process, or both 3.1.14 compression reduction in the number of bits used to represent source image data 3.1.15 component two-dimensional array of samples having the same designation in the output or display device Note 1 to entry: An image typically consists of sever
46、al components, e.g. red, green, and blue. 3.1.16 continuous-tone image image whose components have more than one bit per sample 3.1.17 D C c o e f f i c i e n t DCT coefficient for which the frequency is zero in both dimensions 3.1.18 decoder embodiment of a decoding process2 ISO/IEC 2016 All rights
47、 reservedBS ISO/IEC 18477-6:2016ISO/IEC 18477-6:2016(E) 3.1.19 decoding process process which takes as its input compressed image data and outputs a continuous-tone image 3.1.20 dequantization inverse procedure to quantization by which the decoder recovers a representation of the DCT coefficients 3.
48、1.21 discrete cosine transform DCT either the forward discrete cosine transform or the inverse discrete cosine transform 3.1.22 downsampling procedure by which the spatial resolution of a component is reduced 3.1.23 encoder embodiment of an encoding process 3.1.24 encoding process process which take
49、s as its input a continuous-tone image and outputs compressed image data 3.1.25 entropy-coded (data) segment independently decodable sequence of entropy encoded bytes of compressed image data 3.1.26 entropy decoder embodiment of an entropy decoding procedure 3.1.27 entropy decoding lossless procedure which recovers the sequence of symbols from the sequence of bits produced by the entropy encoder 3.1.28 entropy encoder embodiment of an entropy encoding procedure 3.1.29
