1、 International Telecommunication Union ITU-T T.812TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2007) SERIES T: TERMINALS FOR TELEMATIC SERVICES Still-image compression JPEG 2000 Information technology JPEG 2000 image coding system: An entry level JPEG 2000 encoder ITU-T Recommendation T.812 I
2、TU-T Rec. T.812 (08/2007) i INTERNATIONAL STANDARD ISO/IEC 15444-13 ITU-T RECOMMENDATION T.812 Information technology JPEG 2000 image coding system: An entry level JPEG 2000 encoder Summary The purpose of ITU-T Rec. T.812 | ISO/IEC 15444-13 is to define a normative entry level JPEG 2000 encoder prov
3、iding one or more optional complete encoding paths that use various features defined in the JPEG 2000 specifications. This Recommendation | International Standard provides for an entry-level encoder that can be used in various applications with guidelines on its use, based on patents for which royal
4、ty and license fee free declarations are available. This Recommendation | International Standard defines a set of lossless (bit-preserving) and lossy compression methods for coding bi-level, continuous-tone greyscale, palletized colour, or continuous-tone colour digital still images. Source ITU-T Re
5、commendation T.812 was approved on 29 August 2007 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. An identical text is also published as ISO/IEC 15444-13. ii ITU-T Rec. T.812 (08/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations sp
6、ecialized agency in the field of telecommunications. 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 Recommendations on them with a view to standardizing telecommunications o
7、n 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. The approval of ITU-T Recommendations is covered by the procedure laid d
8、own 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 “Administration“ is used for conciseness to indicate both a telecommunicatio
9、n 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 compliance with the Recommendation is achieved when all of these mandatory
10、 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 Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws atten
11、tion 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 claimed Intellectual Property Rights, whether asserted by ITU members or others
12、 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 Recommendation. However, implementers are cautioned that this may not represent t
13、he latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. T.812 (08/2007) iii
14、 CONTENTS Page 1 Scope . 1 1.1 Context . 1 1.2 Requirements . 1 2 References 1 2.1 Identical Recommendations | International Standards . 1 3 Definitions 2 4 Abbreviations and symbols. 5 4.1 Abbreviations. 5 4.2 Symbols 5 5 General description. 6 5.1 Codestream 6 5.2 Coding principles 6 6 Encoder req
15、uirements 8 6.1 General . 8 6.2 Encoder function definition. 8 6.3 Implementation. 12 6.4 Codestream description 13 7 Optional file format requirements 13 Annex A Codestream syntax 14 Annex B Image and compressed image data ordering . 15 Annex C Arithmetic entropy coding 16 C.1 Binary encoding 16 C.
16、2 Description of the arithmetic encoder 17 Annex D Coefficient bit modelling . 25 D.1 Code-block scan pattern within code-blocks. 25 D.2 Coefficient bits and significance 25 D.3 Encoding passes over the bit-planes 26 D.4 Initializing and terminating . 29 D.5 Error resilience segmentation symbol 31 D
17、.6 Selective arithmetic coding bypass . 31 D.7 Vertically causal context formation. 32 D.8 Flow diagram of the code-block coding . 32 Annex E Quantization 35 E.1 Inverse quantization procedure (Informative) 35 E.2 Scalar coefficient quantization . 36 Annex F Discrete wavelet transformation of tile-c
18、omponents . 37 F.1 Tile-component parameters. 37 F.2 Discrete wavelet transformations 37 F.3 Forward transformation 37 F.4 Sub-sampling of components. 45 F.5 Visual frequency weighting. 45 Annex G DC level shifting and multiple component transformations . 48 G.1 DC level shifting of tile-components.
19、 48 G.2 Forward reversible multiple component transformation (RCT). 48 G.3 Forward irreversible multiple component transformation (ICT) 49 G.4 Chrominance component sub-sampling and the reference grid . 49 Annex H Coding of images with regions of interest 50 H.1 Description of the Maxshift method 50
20、 H.2 Remarks on region of interest coding 51 Annex I JP2 file format syntax . 53 ISO/IEC 15444-13:2008 (E) ITU-T Rec. T.812 (08/2007) 1 INTERNATIONAL STANDARD ITU-T RECOMMENDATION Information technology JPEG 2000 image coding system: An entry level JPEG 2000 encoder 1 Scope This Recommendation | Int
21、ernational Standard was developed by the Joint Photographic Experts Group (JPEG), the joint ISO/ITU committee responsible for developing standards for continuous-tone still picture coding. It also refers to the Recommendations | International Standards produced by this committee: ITU-T Rec. T.81 | I
22、SO/IEC 10918-1, ITU-T Rec. T.83 | ISO/IEC 10918-2, ITU-T Rec. T.84 | ISO/IEC 10918-3 and ITU-T Rec. T.87 | ISO/IEC 14495-1. 1.1 Context This Recommendation | International Standard defines a set of lossless (bit-preserving) and lossy compression methods for coding bi-level, continuous-tone greyscale
23、, palletized colour, or continuous-tone colour digital still images. This Recommendation | International Standard: specifies normative but optional encoding processes for converting source image data to JPEG 2000 compressed image data; specifies a complete encoding path to produce a conforming codes
24、tream as defined in Part 1 Annex A (ITU-T Rec. T.800 | ISO/IEC 15444-1); provides guidance on encoding processes for converting source image data to compressed image data; provides guidance on how to implement these processes in practice. 1.2 Requirements This subclause contains a list of requiremen
25、ts for the definitions of an entry-level encoder. An entry-level JPEG 2000 encoder implementation (this Recommendation | International Standard): shall be normative but optional; implementers shall be allowed to select necessary technologies/paths that would suite their application needs; shall defi
26、ne a JPEG 2000 Part 1 codestream encoder implementation; should define a JP2 file format encoder implementation; shall define a complete encoding path to produce a conforming codestream as defined in Annex A of ITU-T Rec. T.800 | ISO/IEC 15444-1:2004; shall consist of technology with clear IP status
27、 being royalty fee-free. 2 References The following Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated were valid. All Recommen
28、dations and Standards are subject to revision, and parties to agreements based on this Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain register
29、s of currently valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid ITU-T Recommendations. 2.1 Identical Recommendations | International Standards ITU-T Recommendation T.81 (1992) | ISO/IEC 10918-1:1994, Information technology Dig
30、ital compression and coding of continuous-tone still images: Requirements and guidelines. ITU-T Recommendation T.84 (1996) | ISO/IEC 10918-3:1997, Information technology Digital compression and coding of continuous-tone still images: Extensions. ISO/IEC 15444-13:2008 (E) 2 ITU-T Rec. T.812 (08/2007)
31、 ITU-T Recommendation T.86 (1998) | ISO/IEC 10918-4:1999, Information technology Digital compression and coding of continuous-tone still images: Registration of JPEG Profiles, SPIFF Profiles, SPIFF Tags, SPIFF Colour Spaces, APPn Markers, SPIFF Compression Types and Registration Authorities (REGAUT)
32、. ITU-T Recommendation T.87 (1998) | ISO/IEC 14495-1:2000, Information technology Lossless and near-lossless compression of continuous-tone still images Baseline. ITU-T Recommendation T.88 (2000) | ISO/IEC 14492:2001, Information technology Lossy/lossless coding of bi-level images. ITU-T Recommendat
33、ion T.800 (2002) | ISO/IEC 15444-1:2004, Information technology JPEG 2000 image coding system: Core coding system. ITU-T Recommendation T.801 (2002) | ISO/IEC 15444-2:2004, Information technology JPEG 2000 image coding system: Extensions. ITU-T Recommendation T.803 (2002) | ISO/IEC 15444-4:2004, Inf
34、ormation technology JPEG 2000 image coding system: Conformance testing. ITU-T Recommendation T.804 (2002) | ISO/IEC 15444-5:2003, Information technology JPEG 2000 image coding system: Reference software. 3 Definitions For the purposes of this Recommendation | International Standard, the following de
35、finitions apply. The definitions defined in ITU-T Rec. T.800 | ISO/IEC 15444-1:2004 clause 3 also apply to this Recommendation | International Standard. 3.1 5-3 reversible filter (5-3R): A particular filter pair used in the wavelet transformation. This reversible filter pair has 5 taps in the low-pa
36、ss and 3 taps in the high-pass. 3.2 9-7 irreversible filter (9-7I): A particular filter pair used in the wavelet transformation. This irreversible filter pair has 9 taps in the low-pass and 7 taps in the high-pass. 3.3 arithmetic coder: An entropy coder that converts variable length strings to varia
37、ble length codes (encoding) and visa versa (decoding). 3.4 bit-plane: A two-dimensional array of bits. In this Recommendation | International Standard, a bit-plane refers to all the bits of the same magnitude in all coefficients or samples. This could refer to a bit-plane in a component, tile-compon
38、ent, code-block, region of interest, or other. 3.5 bit stream: The actual sequence of bits resulting from the coding of a sequence of symbols. It does not include the markers or marker segments in the main and tile-part headers or the EOC marker. It does include any packet headers and in stream mark
39、ers and marker segments not found within the main or tile-part headers. 3.6 channel: One logical component of the image. A channel may be a direct representation of one component from the codestream, or may be generated by the application of a palette to a component from the codestream. 3.7 cleanup
40、pass: A coding pass performed on a single bit-plane of a code-block of coefficients. The first pass and only coding pass for the first significant bit-plane is a cleanup pass; the third and the last pass of every remaining bit-plane is a cleanup pass. 3.8 codestream: A collection of one or more bit
41、streams and the main header, tile-part headers, and the EOC required for their decoding and expansion into image data. This is the image data in a compressed form with all of the signalling needed to decode. 3.9 code-block: A rectangular grouping of coefficients from the same sub-band of a tile-comp
42、onent. 3.10 coder: An embodiment of either an encoding or decoding process. 3.11 coding pass: A complete pass through a code-block where the appropriate coefficient values and context are applied. There are three types of coding passes: significance propagation pass, magnitude refinement pass and cl
43、eanup pass. The result of each pass (after arithmetic coding, if selective arithmetic coding bypass is not used) is a stream of compressed image data. 3.12 coefficient: The values that are the result of a transformation. 3.13 component: A two-dimensional array of samples. An image typically consists
44、 of several components, for instance representing red, green and blue. ISO/IEC 15444-13:2008 (E) ITU-T Rec. T.812 (08/2007) 3 3.14 context: Function of coefficients previously decoded and used to condition the decoding of the present coefficient. 3.15 decoder: An embodiment of a decoding process, an
45、d optionally a colour transformation process. 3.16 decoding process: A process which takes as its input all or part of a codestream and outputs all or part of a reconstructed image. 3.17 decomposition level: A collection of wavelet sub-bands where each coefficient has the same spatial impact or span
46、 with respect to the source component samples. These include the HL, LH, and HH sub-bands of the same two dimensional sub-band decomposition. For the last decomposition level, the LL sub-band is also included. 3.18 discrete wavelet transformation (DWT): A transformation that iteratively transforms o
47、ne signal into two or more filtered and decimated signals corresponding to different frequency bands. This transformation operates on spatially discrete samples. 3.19 encoder: An embodiment of an encoding process. 3.20 encoding process: A process, that takes as its input all or part of a source imag
48、e data and outputs a codestream. 3.21 file format: A codestream and additional support data and information not explicitly required for the decoding of codestream. Examples of such support data include text fields providing titling, security and historical information, data to support placement of m
49、ultiple codestream within a given data file, and data to support exchange between platforms or conversion to other file formats. 3.22 guard bits: Additional most significant bits that have been added to sample data. 3.23 header: Either a part of the codestream that contains only markers and marker segments (main header and tile part header) or the signalling part of a packet (packet header). 3.24 image area: A rectangular part of the reference grid, registered by offsets from the origin and the extent of the r
