1、BRITISH STANDARD BSISO 9282-1:1988 Implementation of ISO9282-1:1988 Information processing Codedrepresentation of pictures Part 1: Encoding principles for picture representation in a7-bit or8-bit environmentBSISO9282-1:1988 This British Standard, having been prepared under the directionof the Inform
2、ation Systems Technology Standards Policy Committee, was publishedunder the authority ofthe Board of BSI and comes intoeffect on 28 February1991 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/2 Draft for comment 90/68022 DC ISBN 0 580 19354 3 Co
3、mmittees responsible for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/2, upon which the following bodies were represented: British Federation of Printing Machinery and
4、Supplies Ltd. British Radio and Electronic Equipment Manufacturers Association British Telecommunications plc Computing Services Association EEA (Electronics and Business Equipment Association) Institution of Electrical Engineers International Press Telecommunications Council Videotex Industry Assoc
5、iation Amendments issued since publication Amd. No. Date CommentsBSISO9282-1:1988 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword iv Text of ISO9282-1 1BSISO9282-1:1988 ii BSI 01-2000 National foreword This British Standard reproduces verbatim ISO/
6、IEC9282-1:1988 and implements it as the UK national standard. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committee whose Technical Committee IST/2 has the responsibility to: aid enquirers to understand the text; present to the respon
7、sible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from B
8、SI Sales Department, BSI, Linford Wood, Milton Keynes, MK146LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity f
9、rom legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, pages ii to iv, pages1 to24, an inside back cover and abackcover. This standard has been updated (see copyright date) and may have had amendments incorporated. Thi
10、s will be indicated in the amendment table on the inside front cover.ISO9282-1:1988 (E) ii BSI 01-2000 Contents Page Foreword iv Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions and notation 1 3.1 Definitions 1 3.2 Notation 2 3.2.1 7-bit byte 2 3.2.2 8-bit byte 2 3.2.3 Byte interpreta
11、tion 2 3.3 Layout of the code table 2 3.3.1 7-bit representation 2 3.3.2 8-bit representation 3 4 Encoding principles 3 5 Encoding principles for opcodes 3 5.1 General 3 5.2 Compact opcode encoding 4 5.3 Extensible opcode encoding 5 5.3.1 Encoding technique of the basic opcode set 5 5.3.2 Extension
12、mechanism 5 6 Encoding principles for operands 6 6.1 General 6 6.2 Format definitions 7 6.2.1 Basic format 7 6.2.2 Bitstream format 7 6.2.3 String format 8 6.3 General datatypes 9 6.3.1 Unsigned integers 9 6.3.1.1 Unsigned integers in the basic format 10 6.3.1.2 Unsigned integers in the bitstream fo
13、rmat 10 6.3.2 Signed integers 10 6.3.2.1 Signed integers in the modulus-and-sign notation using the basic format 11 6.3.2.2 Signed integers in the twos complement notation using the basic format 12 6.3.2.3 Signed integers in the modulus-and-sign notation using the bitstream format 13 6.3.2.4 Signed
14、integers in the twos complement notation using the bitstream format 14 6.3.3 Real numbers 14 6.3.3.1 Real numbers in the basic format 15 6.3.3.2 Real numbers in the bitstream format 18 6.3.4 Coordinates(2-dimensional) 21 6.3.4.1 Coordinates using real numbers 21 6.3.4.2 Coordinates interleaved coord
15、inate pairs 21 6.3.5 Coordinates(3-dimensional) 22 6.3.5.1 Coordinates using real numbers 22 6.3.5.2 Coordinates interleaved coordinate triplets 22 6.3.6 Point lists in displacement mode 23 7 Conformity 24 Annex A (normative) List and definition of state variables Inside back coverISO9282-1:1988(E)
16、BSI 01-2000 iii Page Figure 1 Compact opcode encoding structure 5 Figure 2 Opcode encoding structure 5 Figure 3 Operand encoding structure 6 Figure 4 Basic format structure 7 Figure 5 Bitstream format structure 7 Figure 6 String format structure in a7-bit environment 8 Figure 7 String format structu
17、re in an8-bit environment 9 Figure 8 Unsigned integer encoding 10 Figure 9 Unsigned integer encoding (more than one byte) 10 Figure 10 Unsigned integer encoding on the bitstream format (one byte) 11 Figure 11 Unsigned integer encoding in the bitstream format (more than one byte) 11 Figure 12 Signed
18、integers in modulus-and-sign notation using the basic format 12 Figure 13 Signed integer encoding in twos complement notation using the basic format 13 Figure 14 Signed integers encoding in modulus-and-sign notation using the bitstream format 14 Figure 15 Signed integers encoding in twos complement
19、notation using the bitstream format 15 Figure 16 Encoding of a mantissa using the basic format 16 Figure 17 Encoding of a mantissa using the basic format 17 Figure 18 A multiple-byte mantissa in the basic format 18 Figure 19 Encoding of a mantissa using the bitstream format 19 Figure 20 Encoding of
20、a mantissa using the bitstream format 20 Figure 21 A multiple-byte mantissa in the bitstream format 21 Figure 22 Encoding of coordinates as interleaved coordinate pairs 22 Figure 23 Encoding of coordinates as interleaved coordinate triplets 23 Table 1 Code table as used for picture coding 4ISO9282-1
21、:1988(E) iv BSI 01-2000 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in
22、 a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commiss
23、ion (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as InternationalStandards by the ISO Council. They are approved in accordance with ISO procedures r
24、equiring at least75% approval by the member bodies voting. International Standard ISO9282-1 was prepared by Technical Committee ISO/TC97, Information processing systems. ISO9282 consists of the following parts, under the general title Information processing Coded representation of pictures: Part1: E
25、ncoding principles for picture representation in a7-bit or8-bit environment. Annex A forms an integral part of this part of ISO9282.ISO9282-1:1988(E) BSI 01-2000 1 Introduction This International Standard provides standard methods for picture coding in order to assist in coding system design and to
26、prevent a proliferation of different unrelated coding techniques. This part of ISO9282 provides a coding scheme for the representation of pictures that can be generated by the majority of computer graphics applications; based on a7-bit structure, this coding scheme may be used in a7-bit or8-bit envi
27、ronment. 1 Scope This part of ISO9282 defines the coding principles to be used in interchanging pictures consisting of graphic images in a7-bit or8-bit environment; the data structures to be used to represent the primitives describing a picture; the general datatypes which can be used as operands wi
28、thin a primitive. This part of ISO9282 does not deal with the presentation semantics of pictures. These are defined in the related International Standards. This part of ISO9282 applies to the data streams containing data structured in accordance with picture coding methods defined in ISO9281. 2 Norm
29、ative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO9282. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO9
30、282 are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISOmaintain registers of currently valid International Standards. ISO646:1983, Information processing ISO7-bit coded character sets for information interchange. IS
31、O2022:1986, Information processing ISO7-bit and8-bit coded character sets Code extension techniques. ISO6429:1983, Information processing ISO7-bit and8-bit coded character sets Additional control functions for character imaging devices. ISO9281:, Information processing Identification of picture codi
32、ng methods 1) . 3 Definitions and notation 3.1 Definitions For the purposes of this part of ISO9282, the following definitions apply: 3.1.1 bit combination; byte an ordered set of bits that represents an opcode or an operand, or used as a part of the representation of anopcode or an operand 3.1.2 co
33、de a set of unambiguous rules that establishes a one-to-one relationship between each opcode or operand of aset and their coded representation by one or more bit combinations within that set 3.1.3 code table a table showing the general distribution of opcodes and operands to bit combinations in a co
34、de 3.1.4 opcode a one or multi-byte coded representation that identifies a function required by a picture standard an opcode may be followed by zero or more operands 1) To be published.ISO9282-1:1988(E) 2 BSI 01-2000 3.1.5 opcode table a table showing the function allocated to each bit combination r
35、eserved for opcodes 3.1.6 operand a single or multiple coded representation used to specify the parameters required by an opcode 3.2 Notation 3.2.1 7-bit byte The bits of a7-bit byte are identified by b 7 , b 6 , b 5 , b 4 , b 3 , b 2and b 1where b 7is the highest-order, or most-significant bit and
36、b 1is the lowest order, or least-significant bit. The bit combinations are identified by notations of the form x/y, where x is a number in the range0 to7 and y is a number in the range0 to15, corresponding to the column and row designation, respectively, of a code table. The correspondence between t
37、he notations of the form x/y and the bit combinations consisting of the bitsb 7to b 1 , is as follows: x is the number represented by b 7 , b 6and b 5where these bits are given the weights4,2 and1, respectively. y is the number represented by b 4 , b 3 , b 2and b 1where these bits are given the weig
38、hts8,4,2 and1, respectively. 3.2.2 8-bit byte The bits of an8-bit byte are identified by b 8 , b 7 , b 6 , b 5 , b 4 , b 3 , b 2and b 1 , where b 8is the highest-order, ormost-significant bit and b 1is the lowest-order, or least-significant bit. The bit combinations are identified by notations of th
39、e form xx/yy, where xx and yy are numbers in the range00 to15. The correspondence between the notations of the form xx/yy and the bit combinations consisting of the bits b 8to b 1 , is as follows: xx is the number represented by b 8 , b 7 , b 6and b 5where these bits are given the weights8,4,2 and1,
40、 respectively. yy is the number represented by b 4 , b 3 , b 2and b 1where these bits are given the weights8,4,2 and1, respectively. 3.2.3 Byte interpretation Bits within a byte may be interpreted to represent numbers in binary notation by attributing the following weights to the individual bits: Us
41、ing these weights, the bit-combinations of the7-bit byte represent numbers in the range0 to127. Thebit-combinations of the8-bit byte represent numbers in the range0 to255. 3.3 Layout of the code table 3.3.1 7-bit representation In a7-bit representation, a code table consists of128 positions arranged
42、 in8 columns and16 rows. Thecolumns are numbered0 to7 and the rows0 to15. The code table positions are identified by notations of the form x/y, where x is the column number and y isthe row number. The positions of the code table are in one-to-one correspondence with the bit combinations. The notatio
43、n ofa code table position, of the form x/y, is the same as that of the corresponding bit combination. Bits of a7-bit byte b 7 b 6 b 5 b 4 b 3 b 2 b 1 Bits of an8-bit byte b 8 b 7 b 6 b 5 b 4 b 3 b 2 b 1 Weight 128 64 32 16 8 4 2 1ISO9282-1:1988(E) BSI 01-2000 3 3.3.2 8-bit representation In an8-bit
44、representation, a code table consists of256 positions arranged in16 columns and16 rows. Thecolumns are numbered and the rows are numbered00 to15. The code table positions are identified by notations of the form xx/yy, where xx is the column number andyy is the row number. The positions of the code t
45、able are in one-to-one correspondence with the bit combinations. The notationofa code table position, of the form xx/yy, is the same as that of the corresponding bit combination. 4 Encoding principles This part of ISO9282 deals with the encoding principles of the opcodes of the primitives; the opera
46、nds of the primitives. All such encoding is defined in terms of a7-bit byte. When used in an8-bit environment, bit b 8of eachbyteshall be zero (except within the “string” format”). Each primitive is coded according to the following rules: a primitive is composed of one opcode and zero or more operan
47、ds as required; the opcodes are encoded in column2 or3 of the Code Table (Table 1); operands are encoded in columns4 to7. (However, the coded representation of a “string” operand mayinclude bit combinations from other columns of the Code Table see the description of string formatin6.2.3.) 5 Encoding
48、 principles for opcodes 5.1 General One of two encoding techniques may be used in the organization of opcodes for the definition of a code table: if the number of opcodes required in a particular standard built upon these coding principles is less than or equal to32, compact structure may be used as
49、 described in5.2; if a greater number of opcodes is required then an extensible structure may be used as describedin5.3. This permits the definition of more efficient code tables when the number of opcodes is small as well asallowing the development of standards which require an unlimited number of opcodes. The identification of either opcode structure is achieved through the identification mechanism defined inISO9281.ISO9282-1:1988(E) 4 BSI 01-2000 Table 1 Code
