1、INTERNATIONAL STANDARD ISOAEC 12089 First edition 1997-12-15 Information technology - Computer graphics and image processing - Encoding for the Image Interchange Facility W) Technologies de /information - lnfographie et traifement de /image - Codage pour /es accessoires pour Ikchange de /image (IIF)
2、 Reference number ISO/IEC 12089: 1997(E) Adopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard.Date of ANSI Approval: 5/27/99Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2002 by I
3、nformation Technology Industry Council (ITI).All rights reserved.These materials are subject to copyright claims of International Standardization Organization (ISO), InternationalElectrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Coun
4、cil(ITI). Not for resale. No part of this publication may be reproduced in any form, including an electronic retrieval system, withoutthe prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the Unite
5、d States of AmericaISO/IEC 12089:1997(E) Foreword IS0 (the International Organization for Standardization) and IEC (the Inter- national Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the developmen
6、t of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental,
7、in liaison with IS0 and IEC, also take part in the work. In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication a
8、s an International Standard requires approval by at least 75 % of the national bodies casting a vote. International Standard ISO/IEC 12089 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 24, Computer graphics and image processing. 0 ISO/IEC 1997 All r
9、ights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechamcal, including photocopying and micro- film, without permission in writing from the publisher. ISO/IEC Copyright Office l Case postale 56 l CH-1211 G
10、entve 20 l Switzerland Printed in Switzerland ii INTERNATIONAL STANDARD 0 ISO/IEC ISO/IEC 12089:1997(E) Information technology - Computer graphics and image processing - Encoding for the Image Interchange Facility (1 IV 1 Scope This International Standard defines the encoding rules which shall apply
11、 to the representation of IPI-IIF image data. The IPI-IIF data format is defined in ISO/IEC 12087-3, called Jmage Interchange Facility (IIF)“. It is Part 3 of the Image Processing and Interchange International Standard, defined in ISO/IEC 12087. The IPI-IIF facilitates the interchange of digital ima
12、ges. It consists of two major parts: (1) the IPI-IIF data format (IIF-DF) definition, whose syntax is described using ASN. 1; (2) the IPI-IIF gateway definition, whose functionality is described by an application programmers interface. The IPI-IIF is based on the definition described in Part 1, Comm
13、on Architecture for Imaging (CAI) of the ISO/IEC 12087. Due to the fact that the syntax of the IIF-DF is expressed using the Abstract Syntax Notation One (ASN.1) defined by ISO/IEC 8824, this standard makes use of the Basic Encoding Rules (BER) for ASN.1, by referring to ISO/IEC 8825 for the definit
14、ion of encoding rules. NOTE - A rationale for the introduction of new encoding rules in addition to those defined by the BER is given in clause 4. Reference shall be made to this International Standard, and its definitions shall be employed, whenever images are interchanged, according to the IIF-DF,
15、 defined in ISO/IEC 12087-3. 1 ISO/IEC 12089:1997(E) 0 ISO/IEC 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards a
16、re subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. ISO/IEC 86
17、32:(all parts), In$ormation technology - Computer graphics - Metafile for the storage and transfer of ISO/IEC 8824: 1990, ISO/IEC 8825: 1990, ISO/IEC 8825-2: 1996, ISO/IEC 12087- 1: 1995, ISO/IEC 12087-2: 1994, ISO/IEC 12087-3:1995, picture description information. Information technology - Open Syst
18、ems Interconnection - Specification of Abstract Syntax Notation One (ASN. I). Information technology - Open Systems Interconnection - Specification of Basic Encoding Rules for Abstract Syntax Notation One (ASN.1). Information technology - ASN.1 encoding rules: Specification of Packed Encoding Rules
19、(PER). Information technology - Computer graphics and image processing - Image Processing and Interchange (IPI) - Functional specification - Part 1: Common architecture for imaging. Information technology - Computer graphics and image processing - Image Processing and Interchange (IPI) - Functional
20、specification - Part 2: ProgrammerS imaging kernel system application programme intetiace. Information technology - Computer graphics and image processing - Image Processing and Interchange (IPI) - Functional specification - Part 3: Image Interchange Facility (IIF). NOTE - Some IS0 Standards are tec
21、hnically aligned with CCllT Recommendations, in particular the ASN. 1 Standard (IS0 Standards 8824/8825 and CCIIT Recs. X.208/X.209). The differences between the International Standard definitions and the CCIIT definitions are quite small, and should not affect interoperability between implementatio
22、ns written against either document. Within this part of ISOlIEC 12087, the IS0 Standards are referenced whenever possible. 0 ISO/IEC ISO/IEC 12089:1997(E) 3 Definitions and abbreviations ASN. 1 Abstract Syntax Notation One BER Basic Encoding Rules frc fraction lsb least significant bit IsB least sig
23、nificant Byte msb most significant bit msB most significant Byte S sign NOTE - For definitions and abbreviations concerning the Image Processing and Interchange Standard (IPI), refer also to clause 3 of ISO/IEC 12087- 1, ISO/IEC 12087-2 and ISO/IEC 12087-3. 3 ISO/IEC 12089:1997(E) 0 ISO/IEC 4 Encodi
24、ng rules for the IIF syntax entities The encoding of syntax entities shall conform to the Basic Encoding Rules (BER) for ASN. 1 - ISO/IEC 8825. NOTE - Using the BER encoding overheads may occur. In particular, the encoding of a large pixel data field can produce considerable space and processing tim
25、e overhead, when every pixel is represented as an elementary ASN.1 data entity, consisting of a ,tag“ and a ,length“ field that proceeds the ,value“ field. For this reason this International Standard describes additional encoding methods that may be applied to pixel fields. These methods may neither
26、 be regarded as extensions, nor as changes to the tag-length-value concept of the BER. Instead, they only describe how to interpret the data contained in the elementary ASN.1 type OCTET STRING, when this elementary type was used to encode an entire field of pixel values (instead of just one value).
27、Thus, these encoding rules may rather be regarded to lie ,on top of BER encoding/decoding tools. This International Standard defines additional encodings for space-efficient representation of pixel fields. They are outlined in clause 5 in conjunction with additional IIF syntax entities which describ
28、e the degree of freedom for the selection of an encoding method. 0 ISO/IEC 5 IIF syntax entities for the representation of pixel fields ISO/IEC 12089:1997(E) The syntax is expressed in ASN.1 (Abstract Syntax Notation One), according to ISO/IEC Standard 8824, “Specification of Abstract Syntax Notatio
29、n One (ASN. l).” ASN.1 is a formal description language. It defines a set of primitive data types, such as INTEGER. ENUMERATED, and REAL and provides a facility to construct new elements with their own typing inherent in the structure using the constructors SEQUENCE, SEQUENCE OF and CHOICE. This all
30、ows for new data types to be defined which are uniquely recognisable within an application. To make these definitions more readable, textual labels may be associated with the elements in a constructor type. In order to distinguish different occurrences of the same type within one constructor, variou
31、s types of tags are provided that may be associated with the constructors elements. Within the semantic description each element (which is either a primitive data type or a constructed type) is called syntax entity. According to ASN.1, the names of the syntax entities begin with capital letters. Syn
32、tax entities consist of a number of components. According to ASN.1, the component labels begin with lower case letters. In the following, ASN.1 code is indicated by courier font. All syntax rules are preceded by a semantics statement. Some rules are succeeded by constraints statements. The rules are
33、 ordered in prefix form. 5 ISO/lEC 12089: 1997(E) IIF module declaration 0 ISO/IEC IIFEncoding Semantics flFEncoding is the name of the ASN. 1 module responsible for the encoding of fields of pixel values to be used mainly by the IIF-DF. Besides the full syntax (given by the PixelFieldEncoding entit
34、y), the module also exports the BooleanEncoding, IntegerEncoding, FixedPointEncoding, RealEncoding, ComplexEncoding and the EnumeratedEncoding entities. This provides other ASN.1 notated applications with direct access to these sub- objects. No objects are imported. In order to obtain the full synta
35、x for the module specification, the term needs to be replaced with the syntax portions of all subsequent syntax entities within this clause. IIFEncoding iso standard (0) ipi-encoding(12089) iif-encoding(l) DEFINITIONS := BEGIN EXPORTS PixelFieldEncoding, BooleanEncoding. IntegerEncoding, FixedPointE
36、ncoding, RealEncoding, ComplexEncoding, EnumeratedEncoding; IMPORTS; END Constraints None. 0 ISO/IEC ISO/IEC 12089:1997(E) IIF syntax entity No. 1001 PixelFieldEncoding Semantics The PixelFieldEncoding entity is used to represent a field of pixel values whose structure is defined by an external imag
37、e structure definition. NOTE - In case of the IIF-DF, this image structure definition is given by the ImageStructure entity The byte-order-swapped component indicates the sequential order in which consecutive octets appear within the corresponding pixel-value component. The definitions of subsequent
38、 data types apply after octet swapping, if specified. Possible values are: ,o” The physical order matches the significance: I 6 5 4 3 2 1 0 17161514131211101 -_- 1 I 1, The octets are swapped: 7 6 5 4 3 2 1 0 161714151213IOI11 -_- NOTE -When using ASN. 1, machine dependencies, such as byte swapping
39、are managed by the BER. However, within the PixelFieldEncoding entity an ASN.1 OCTET STRING is used to represent not just one value, but multiple values of various types such as integer or real. Thus, these machine dependencies need to be managed by the application again. The encoding-rules componen
40、t determines the encoding rules that apply to the field of pixel values. The pixel-values component represents the field of pixel values by the ASN. 1 type BITSTRING. NOTE -A field element is either the value of a pixel, or the value of an elementary part of a pixel, depending on whether the pixel t
41、ype is defined to be elementary or compound (e.g., a record of some elementary types). Syntax: PixelFieldEncoding := SEQUENCE byte-order-swapped O INTEGER (Ol), encoding-rules l EncodingRules, pixel-values 23 BITSTRING I Constraints The number field elements contained in the pixel-values component m
42、ust match the number of array elements declared by the corresponding image structure definition. ISO/IEC 12089:1997(E) 0 ISO/IEC IIF syntax entity No. 1002 EncodingRules Semantics The EncodingRules entity provides a generic method for the specification of the packed encoding of pixel values. The uni
43、form-encoding component describes the encoding of heterogeneous pixel fields, while the hierarchical-encoding component facilitate the description of the complex hierarchical encodings. EXAMPLE - Given a 2D image, which consists of two bands, called hi and lo, whereby hi has three times the resoluti
44、on of lo in both dimensions: 192x192 pixels for hi, and 64x64 pixels for lo. According to its image structure definition, the image is represented pixel-interleaved, i.e. it consists of 3 by 3 blocks of hi pixels followed by a single lo pixel, followed by another block of hi pixels, etc. Let us now
45、look at two cases 1) Let us assume that both bands have 8 bit unsigned integer pixels: In this case the pixel values of both bands are represented in the same way. Thus, on the level of the encoding specification it is not necessary to express the complex pixel interleaved organisation. Instead it i
46、s sufficient to specify a plain (l-dimensional) sequence of 8 bit integers. The iteration component is being set to 49960 = 192x192 + 64x64. The bit pad component is set to zero, since no padding bits occur in the sequence. EncodingRules uniform-encoding iteration-and-alignments explicit-iteration a
47、lignment bit-pad components-encoding non-negative-integer number-of-bits = SEQUENCE OF = IterationAndAlignment = INTEGER = Padding = INTEGER = SEQUENCE OF = ElementEncoding = UnsignedIntegerEncoding = INTEGER 40960 0 8 2) Let us assume that hi band consists of 6 bit integers and the low band consist
48、s of 4 octet floats. In this heterogeneous case a hierarchical encoding specifications is required, if each block of pixel elements is aligned to a 2 octet boundary. The first level describes the loop over pixel blocks. The second level describes the representation within one block. EncodingRules hi
49、erarchical-encoding iteration-and-alignment explicit-iteration alignment octet-boundary components-encoding elementary-component non-negative-integer number-of-bits L elementary-component real ieee-basic-single = IterationAndAlignment = INTEGER = Padding = INTEGER = SEQUENCE OF = ComplexEncoding = ElementEncoding = UnsignedIntegerEncoding = INTEGER = ComplexEncoding = ElementEncoding = RealEncoding = NULL 64 2 6 0 ISO/IEC Syntax EncodingRules := CHOICE uniform-encoding Ol UniformEncoding, hierarchical-enc
