1、Adopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard.Date of ANSI Approval: 12/30/2003Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2003 by Information Technology Industry Council
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4、/IEC 14495-2:2003(E)ISO/IEC 2003INTERNATIONAL STANDARD ISO/IEC14495-2Second edition2003-04-01Information technology Lossless and near-lossless compression of continuous-tone still images: ExtensionsTechnologies de linformation Compression sans perte et quasi sans perte dimages fixes model continu: E
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9、s below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2003 All rights reservedISO/IEC 14495-2:2003(E) ISO/IEC 2003 Al
10、l rights reserved iiiCONTENTS Page 1 Scope 1 2 Normative references . 1 2.1 Identical Recommendations | International Standards 1 2.2 Additional references 1 3 Definitions, abbreviations, symbols and conventions 2 3.1 Definitions. 2 3.2 Abbreviations 2 3.3 Symbols. 2 4 General . 3 4.1 Extensions spe
11、cified by this Recommendation | International Standard. 4 4.1.1 Encoding with arithmetic coding 4 4.1.2 Extension of near-lossless coding . 4 4.1.3 Extension of prediction . 5 4.1.4 Extension of Golomb coding 5 4.1.5 Fixed length coding. 5 4.1.6 Sample transformation for inverse colour transforms .
12、5 4.2 Descriptions of extended functions . 5 5 Interchange format requirements 6 6 Encoder requirements. 6 7 Decoder requirements. 6 8 Conformance testing for extensions . 7 8.1 Purpose 7 8.2 Encoder conformance tests 7 8.3 Decoder conformance tests . 7 Annex A Encoding procedures with arithmetic co
13、ding for a single component. 10 A.1 Coding parameters and compressed image data 10 A.2 Initializations and conventions 10 A.2.1 Initializations. 10 A.2.2 Conventions for figures. 12 A.3 Context determination. 12 A.3.1 Local gradient computation. 12 A.3.2 Flat region detection 13 A.3.3 Local gradient
14、 quantization. 13 A.3.4 Quantized gradient merging 14 A.3.5 Adjustment of error tolerance for near-lossless coding with visual quantization 14 A.4 Prediction 14 A.4.1 Edge-detecting predictor . 14 A.4.2 Prediction correction . 14 A.4.3 Computation of prediction error 15 A.4.4 Error quantization for
15、near-lossless coding, and reconstructed value computation 16 A.4.5 Modulo reduction of the prediction error 16 A.5 Prediction error encoding 16 A.5.1 Error mapping . 17 A.5.2 Binarization of MErrval with the Golomb code tree. 17 A.5.3 Mapped-error encoding. 18 A.6 Update variables 18 A.6.1 Update. 1
16、8 A.6.2 Bias computation. 21 A.7 Flow of encoding procedures 22 ISO/IEC 14495-2:2003(E) iv ISO/IEC 2003 All rights reservedPage Annex B Arithmetic coding 24 B.1 Arithmetic encoding procedures . 24 B.1.1 Binary arithmetic encoding principles 24 B.1.2 Procedures of arithmetic coding 25 B.2 Arithmetic
17、decoding procedures . 28 B.2.1 Binary arithmetic decoding principles 28 B.2.2 Procedures of arithmetic decoding 28 Annex C Encoding with arithmetic coding for multiple component images 30 C.1 Introduction. 30 C.2 Line interleaved mode. 30 C.2.1 Description 30 C.2.2 Process flow 30 C.3 Sample interle
18、aved mode 30 C.3.1 Description 30 C.3.2 Process flow 31 C.4 Minimum coded unit (MCU) 31 Annex D Extended functions for the baseline coding model 32 D.1 Extensions of near-lossless coding 32 D.1.1 Near-lossless coding with visual quantizaion . 32 D.1.2 Near-lossless coding with NEAR value re-specific
19、ation 32 D.2 Extensions of prediction on baseline coding model 33 D.2.1 Initializations. 33 D.2.2 Prediction correction . 33 D.2.3 Symbol packing. 33 D.2.4 Update variables 34 D.2.5 Run interruption sample encoding 35 D.2.6 Flow of encoding procedures 35 D.3 Extension of Golomb coding. 35 D.3.1 Golo
20、mb code completion 36 D.3.2 Run interruption handling for qbpp=1 36 Annex E Fixed length coding . 37 E.1 Introduction. 37 E.2 Fixed length coding. 37 Annex F Sample transformation for inverse colour transform . 38 F.1 Inverse colour transform . 38 F.2 Example and guideline (Informative) 39 Annex G C
21、ompressed data format 41 G.1 General aspects of the compressed data format specification . 41 G.1.1 Marker assignments 41 G.1.2 JPEG-LS preset parameters specification syntax 41 Annex H Control procedures for extensions. 48 H.1 Control procedure for encoding a restart interval 48 H.2 Control procedu
22、re for encoding a minimum coded unit (MCU) with fixed length code (FLC) . 48 Annex I Conformance tests. 51 I.1 Test images . 51 I.1.1 Source images . 51 I.1.2 Compressed image data. 51 I.1.3 Test image formats 51 Annex J Patents 53 J.1 List of patents 53 Annex K Bibliography 55 ISO/IEC 14495-2:2003(
23、E) ISO/IEC 2003 All rights reserved vForeword 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 I
24、nternational 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 lia
25、ison 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 tec
26、hnical 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
27、 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. ISO/IEC 14495-2 was prepared jointly by Joint Technical Committee ISO/IEC JTC 1, Information technology,
28、Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, in collaboration with ITU-T. The identical text is published as ITU-R Recommendation T.870. This second edition cancels and replaces the first edition (ISO/IEC 14495-2:2002), which has been technically revised. ISO/
29、IEC 14495 consists of the following parts, under the general title Information technology Lossless and near-lossles compression of continuous-tone still images: Part 1: Baseline Part 2: Extensions ISO/IEC 14495-2:2003 (E) ITU-T Rec. T.870 (03/2002) 1 INTERNATIONAL STANDARD ITU-T RECOMMENDATION Infor
30、mation technology Lossless and near-lossless compression of continuous-tone still images: Extensions 1 Scope This Recommendation | International Standard defines a set of lossless (bit-preserving) and nearly lossless (where the error for each reconstructed sample is bounded by a predefined value) co
31、mpression methods for coding continuous-tone (including bi-level), gray-scale, or colour digital still images. This Recommendation | International Standard: specifies extensions (including arithmetic coding, extension of near lossless coding, extension of prediction and extension of Golomb coding) t
32、o processes for converting source image data to compressed image data; specifies extensions to processes for converting compressed image data to reconstructed image data including an extension for sample tranformation for inverse colour transforms; specifies coded representations for compressed imag
33、e data; provides guidance on how to implement these processes in practice. 2 Normative references The following Recommendations and International Standards contain provisions which, through references in this text, constitute provisions of this Recommendation | International Standard. At the time of
34、 publication, the editions indicated were valid. All Recommendations 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 Sta
35、ndards listed below. Members of IEC and ISO maintain registers 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 CCITT Recommendation T
36、.81 (1992) | ISO/IEC 10918-1:1994, Information technology Digital compression and coding of continuous-tone still images: Requirements and guidelines. ITU-T Recommendation T.83 (1994) | ISO/IEC 10918-2:1995, Information technology Digital compression and coding of continuous-tone still images: Compl
37、iance testing. ITU-T Recommendation T.84 (1996) | ISO/IEC 10918-3:1997, Information technology Digital compression and coding of continuous-tone still images: Extensions. ITU-T Recommendation T.87 (1998) | ISO/IEC 14495-1:2000, Information technology Lossless and near-lossless compression of continu
38、ous-tone still images: Baseline. 2.2 Additional references ISO/IEC 646:1991, Information technology ISO 7-bit coded character set for information interchange. ISO 5807:1985, Information processing Documentation symbols and conventions for data, program and system flowcharts, program network charts a
39、nd system resources charts. ISO/IEC 9899:1999, Programming languages C. ISO/IEC 14495-2:2003 (E) 2 ITU-T Rec. T.870 (03/2002) 3 Definitions, abbreviations, symbols and conventions 3.1 Definitions For the purposes of this Recommendation | International Standard, the following definitions apply in add
40、ition to the definitions used in ITU-T Rec. T.87 | ISO/IEC 14495-1. 3.1.1 arithmetic encoder: An embodiment of an arithmetic encoding procedure. 3.1.2 arithmetic encoding: A procedure which encodes a sample as a binary representation of the sequence of previously encoded samples by means of a recurs
41、ive subdivision of a unit interval. 3.1.3 arithmetic decoder: An embodiment of an arithmetic decoding procedure. 3.1.4 arithmetic decoding: A procedure which recovers source data from an encoded bit stream produced by an arithmetic encoder. 3.1.5 binary context: Context used to determine the binary
42、arithmetic coding of the present binary decision. 3.1.6 binary decision: Choice between two alternatives. 3.1.7 colour transform: A procedure for sample transformation for inverse colour transform. 3.1.8 sign flipping: The procedure which reverses the sign of a prediction error according to accumula
43、ted prediction errors. 3.1.9 symbol packing: A procedure which may be applied to source images in which sample values are sparsely distributed. 3.1.10 visual quantization: An extended function of near-lossless coding which enables to change the difference bound according to the context. 3.2 Abbrevia
44、tions In additions to the abbreviations used in ITU-T Rec. T.87 | ISO/IEC 14495-1, the abbreviations used in this Recommendation | International Standard are listed below. FLC Fixed length code LPS Less probable symbol MPS More probable symbol 3.3 Symbols In addition to the symbols used in ITU-T Rec
45、. T.87 | ISO/IEC 14495-1, the symbols used in this Recommendation | International Standard are listed below. A convention is used that parameters which are fixed in value during the encoding of a scan are indicated in boldface capital letters, and variables which change in value during the encoding
46、of a scan are indicated in italicised letters. Areg current numerical-line interval being renormalized ArithmeticEncode() a function in the C programming language Av030 31 constants corresponding to LPS probability estimate Avd auxiliary variable storing modified Av BASIC_T1, BASIC_T2, BASIC_T3, BAS
47、IC_T4 basic default threshold values Bin binary decision Buf 01 bytes stored to avoid carry-over propagation to the encoded bit stream Creg value of code register storing the trailing bits of the encoded bit stream ENT indication of the coding process used for the scan Flag0MAXVAL MAXVAL+1 flags whi
48、ch indicate if corresponding sample values already occurred ISO/IEC 14495-2:2003 (E) ITU-T Rec. T.870 (03/2002) 3 GetBinaryContext() a function in the C programming language GetByte() a function in the C programming language GetGolombk() a function in the C programming language Hd auxiliary variable
49、 storing an integer value corresponding to a half of the full range but shifted according to the size of the current interval LPScnt0MAXS accumulated occurrence count of the LPS (less probable symbol) at each binary context MAXcnt threshold value at which MLcnt and LPScnt are halved MAXS maximum index of binary contexts MLcnt0MAXS accumulated occurrence count of each binary context MPSvalue0MAXS sense of the MPS (more probable symbol) at each binary context nea
