This standard specifies a standard method for picture coding in order to assist in the design of coding systems and to prevent the proliferation of various unrelated coding techniques. This part of the standard specifies a coding scheme for picture representations that can be generated by most computer graphics applications; this coding scheme is based on a seven-bit structure and can be used in a seven-bit or eight-bit environment. GB/T 14815.1-1993 Information processing picture coding representation Part 1: Coding principles for picture representation in a seven-bit or eight-bit environment GB/T14815.1-1993 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Information processing
Enfarmation processing Coded rcpresental of picturcs -Part 1: Encoding principles for picture representation in a 7-bit or 8-bit environment
Enfarmation processing Coded rcpresental of picturcs -Part 1: Encoding principles for picture representation in a 7-bit or 8-bit environment CB/T14B15.1—93
ISO 9282. 1-1988
This standard is equivalent to the international standard ISO 9282.1—1988. Information processing Coded rcpresental of picturcs -Part 1: Encoding principles for picture representation in a 7-bit or 8-bit environment. This standard specifies a standard method for picture coding in order to assist in the design of coding systems and to prevent the proliferation of various unrelated coding techniques. This part of the standard specifies a coding scheme for the representation of pictures that can be generated by most computer graphics applications; this coding scheme is based on a seven-bit structure and can be used in a seven-bit or eight-bit environment. 1 Subject matter and scope This part of the standard specifies: a. Coding principles for exchanging picture information consisting of images in a seven-bit or eight-bit environment; h. Data structures for representing image primitives used to describe pictures; c. General data types that can be used as operands in image primitives. This part of the technical standard does not involve the semantics of picture representation, which are specified in other relevant standards. This part of the standard applies to data streams consisting of data constructed according to the picture coding method specified in G1310022. 2 Referenced standards The following standards contain provisions that, through reference in this standard, constitute provisions of this standard. At the time of publication, the versions indicated were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB198 Information processing Seven-bit coded character set for information exchange GB2311
GR5261
Information processing Seven-bit and eight-bit coded character set code protection technology Text and symbol forming equipment for additional control functions GB10022
Information processing, identification of image coding methods 3 Terminology and notation
3.1 Language
This part of this standard uses the following term definitions: 3-1-1 Byte
If the ordered combination of ten binary bits is used to represent an operation code or operand, or used as an operation code or operand code representation State Technical Supervision Bureau 1993-12-24 Approved 19940801 for implementation of
part,
3.1.2 Code
GB/T14815.1-93
set of clear rules, using ten to determine the one-to-one correspondence between each operation code or operand in a set and its coded representation consisting of one or more bit groups.
3.1. 3 Code difference
indicates the total allocation table of operation codes and operands in the code and their bit groups. 3.1.4 Operation code
One or more bytes of coded representation used to identify a function required by the image standard. The operation code can be followed by zero or more operands.
3.1.5 Operation code table
indicates a table of control functions assigned to each bit group reserved for the operation code. 3.1.6 Operand
One or more codes used to specify the parameters required by the operation code, 3.2 Notation
3.2.1 Seven-bit byte
Each bit of a seven-bit byte is identified by h,,h,h,,h,,hs,bz,h,, where b is the most significant bit and b is the least significant bit. Bit groups are identified by a/-shaped notation, where a is a number in the range of 0 to 7, and b is a number in the range of 0 to 15, corresponding to the columns and rows indicated in the code table, respectively. The correspondence between the notation in the form of
r/ and the bit groups consisting of h, to h, bits is as follows: ax is h,,b is a number in the range of 0 to 15, respectively. and t, the numbers represented by b,, b, and b, are assigned weights of 4, 2 and 1 respectively. 1b is the number represented by b,, b,b. and br, and the weights assigned to b,, b,.h, and b, are 8, 4.2 and 13 respectively. 2.2 The eight-bit byte
is represented by each mountain of the eight-bit byte b,, b,, ba, b., b,b..b. and b, where be is the highest bit and b, is the lowest bit. The group is identified by the notation of the form r/, where and are numbers in the range of ~15. The correspondence between the notation of the form and the bit group composed of bits from b, is as follows:. r is the number represented by b,,, b. and h, and the weights assigned to b, b,, b. and b, are 84, 2 and 1 respectively; b.3y is the number represented by b, bs, hz and b, and the weights assigned to b, b,.b and bi are 8, 4.2 respectively. 3.2.3 Byte Interpretation
By weighting each bit with the following weights, each bit in a byte can be interpreted as representing a number in binary notation: ||tt| ... The notation of code table positions in 2/3 form is the same as the corresponding bit group notation.
Eight-bit code representation
CB/T 14815. 193
In eight-bit code representation, the code table consists of 256 positions arranged in 16 columns and 16 rows, the columns and rows being numbered 0013.
Code table positions are identified by a notation of the form /, where is the column number and is the row number. There is a one-to-one correspondence between code table positions and bit groups.
4 Coding principles
This part of the standard deals with:
a. Coding principles for the operation codes of graphics primitives;
h. Coding principles for the operands of graphics primitives.
All such encodings are defined in seven-bit bytes. When used in an 8-bit environment, the Bth bit of each byte is 0 (except for the case of NULL characters). Each table is encoded according to the following rules: The table consists of an operation code and zero or more operands. The operation code is encoded in column 2 or column 3 of the code table (Table 1): the operands are encoded in columns 4 to 7 (but the encoding of a string operand may include bit groups in other columns of the code table, see 6.2.3 for the description of strings).
b, b, b, I b
5 Coding principles for operation codes
5.1 Overview
GB/T 14815.1-93
Table] Code table for pictures
Control power
When organizing the operation codes for defining the code table, one of the following two abbreviation techniques can be selected:bzxZ.net
GB/T 14815.1—93
If the number of operation codes required in a particular specification of this coding principle is less than or equal to 32, the compact structure described in 5.2 can be used:
b. If more operation codes are required, the expandable structure described in 5.3 can be used. In this way, when fewer opcodes are needed, or when an unlimited number of opcodes are required, a more efficient code can be defined. The above opcode structures are all identified by the identification mechanism defined in GB10022. 5.2 Compact opcode encoding
When 32 or less opcodes are required, the encoding of the operation can be simply completed by assigning a code table position to each opcode from the 32 code table positions in code table list 2 and list 3. The general structure of this type of opcode is shown in Figure 1. Opcode list
Figure 1 Compact opcode encoding structure
5.3 Extra opcode encoding
Opcode
When the number of possible opcodes is unlimited, the encoding of the opcodes requires dividing the opcodes into: a basic opcode set
b extended opcode set.
5.3.1 gives a description of the encoding technology of the basic opcode set. 5.3.2 gives a description of the expansion mechanism. 5.3.1 Encoding technology of basic opcode nests
The basic opcode set consists of single-byte and double-byte opcodes: the general structure of this type of opcode is shown in Figure 2. For single-byte opcodes, the opcode length indicator bit is 0 (opcode in column 2), and bits b to h are used to encode the opcode. 6,
Operation code flag
Operation code length indicator
Operation code length indicator
Operation code length indicator
Figure 2 Operation code encoding structure
For double-byte operation codes, the first bit of the operation code length indicator is 1, and bits b1 to b2 of the first word and bits b3 to b4 of the second word are used to encode the operation code. Bit 3/15. The extended operation code interval (EOS) is used for other purposes (see 5.3.2). Therefore, this encoding technique can provide a basic opcode set containing 496 opcodes, namely: a. 16 single-byte opcodes (column 2 in the code); b. 180 (i.e. 15×32) double-byte opcodes (the first byte is taken from the bit group other than 3/15 in column 3. The second byte is taken from column 2 or column 3).
5.3.2 Expansion Mechanism
The expansion operation interval can be used to randomly<2/±)
(3/y)(3/yuan)
The number of opcodes (basic opcode set and extended opcode set) provided by this encoding technique is: 16 single-byte opcodes, taken from the basic opcode set (operation format 1-0).
h. 480 double-byte opcodes, taken from the basic opcode set (opcode format 2 and 3.\-0) 116 double-byte opcodes, taken from the extended opcode set (opcode format 1,\-1); 480 N-byte opcodes, taken from the extended opcode set N-2 (opcode format 2 and 3 = N-2); 16 N-byte opcodes, taken from the extended opcode set N-1 (opcode format 1.n = N-1). 6 Encoding principles for operands
6.1 Overview
The operand part of the original can contain any number of operands, including zero. Each such operand may consist of a single byte or multiple bytes. The general format of the operand byte is given in Figure 3. 6.2 Format Definition
Operation Number Flags -
CB/T 14815.1:-93
Figure 3 Operand Encoding Structure
Operation numbers may be encoded in the following three formats: Basic format;
Bit stream format:
String format.
Operands
In addition, the encoding of operands may be controlled by state variables. The state variables are set to a desired value by the specific application at the initialization of the encoding/evaluation process. The state variables may remain fixed or be dynamically modified by the functions specified in the functional standard, depending on the functional standard under which the encoding primitives defined in this part of this standard are used. The state variables used in this part of this standard are listed in Appendix A (Supplement). This part of this standard only refers to the values ​​of the state variables, but does not involve the functional definitions that allow them to be modified. 6.2.1 Basic format
The operand in the basic format is represented as a single-byte or multi-byte sequence, and its tree is shown in Figure 4. ba
Circle 4 Basic format structure
Data bit
Extension flag
Operand flag
For a single-byte operand, the extension flag b bit is 0. In a multi-byte operand, the extension flags in all bytes are 1 except the last byte, which has an extension flag of 0. 6.2.2 Bitstream format
The operation code in the bitstream format is represented as a single-byte or multi-byte sequence, and its structure is shown in Figure 5: &
CB/T 14815.1-93
Figure Bitstream format structure
Number of bits
Operand flags
The number in the bitstream format refers to the data bits loaded continuously in the operand bytes from the high bit to the low bit of the first section of the bitstream data effect part. The end of the bitstream format operand cannot be derived from the bitstream format itself (the format cannot be delimited). The end of the bitstream format operand is delimited by a. the next operation code; or
h. The "end of block" value, which marks the end of the data in the operand encoded in the bitstream format; or c. the status variable value, which defines the length of the operand encoded in the bitstream format. When the data encoded in the bit stream format does not match the total number of all bytes, the remaining bits of the highest byte shall be filled with "0". 6.2.3 Format
The operand in the format is encoded in the form of a byte sequence, and its structure is shown in Figures 6 and 7. be
Byte 1 (F5) (1/11)
Byte 2 (5/R)
Byte 3
Byte 4
Byte 5 (5/12)
Figure 6 Structure of the format in a seven-bit environment (data bits are marked with c) GB/T 14815. 1-93
1st byte (S0S) (09/08)
2nd byte
3rd byte
4th byte (5T) (09/12)
Figure 4 String format structure in six-bit environment (using mark data bit) The start delimiter in the string is indicated by the start of the string (SOS>). The delimiter is indicated by the control sequence ESC5/8 in the seven-bit environment (ESC:1/11 and 09/08 in the eight-bit environment. The end delimiter in the string is indicated by the string terminator (ST). The delimiter is indicated by the escape sequence ESC5/12 in the ten-bit environment (ESC=1/11) and In the seven-bit environment (Figure 6), the bit group in column (7) of the code table, that is, the 3rd to the (2nd) byte, can be used as a data byte. Standards that use string format operands may limit the use of the bit group in column 0 to 1 of the code table. In the eight-bit environment (Figure 7, the bit group in column 00 to 15 of the code table, that is, the 2nd to the (m:1)th byte, can be used as a data byte. Standards that use string format operands may limit the use of the bit group in column 00 to 01 and column 08 to 09 of the code table. In the seven-bit environment, the number of bytes required to encode an operand is equal to the number of string characters plus 4 (these 4 bytes are used as 5 OS R ST, which are encoded as ESC:5/8 respectively. and ES(5/12). In an 8-bit environment, the number of bytes required to encode a string operation is equal to the number of characters in the string plus 2 (these two sections are used as SS and ST, and are encoded as 09/08 and 09/12 respectively). The encoding of strings is the only exception to the general encoding rules described in 6.1. 6-3 Common data types
This clause describes the encoding of several common data types using the format defined in 6.2. These common data types can be used in picture representation standards. If a particular standard uses a common data type, the encoding of that data type in the standard must The encoding of the applicable data type is consistent with that described in the technical clause. 6.3.1 Unsigned integers
Unsigned integers are encoded in basic format or bitstream format, and the format used is determined by the function using the encoding principles of this standard.
Each unsigned integer is represented as a single byte or a multi-byte sequence. The data bits are loaded into each word consecutively starting from the most significant bit to the least significant bit of the first byte of the most significant part of the operand. 6.3.1.1 Unsigned integers in basic format Examples of unsigned integers encoded in basic format are shown in Figures 8 and 9.
GH/T 14815. 1—93
Operand value: 31
8 Unsigned integer encoding
Operand digits: 2079
Figure 9 Unsigned integer encoding (more than 1 byte) 6.3.1.2 Unsigned integer operands in bitstream format The number of sections used is determined by the unsigned integer length state variable. Examples of unsigned integers encoded in bitstream format are shown in Figures 10 and 11. he
Operand value: 63
Unsigned integer length: 1
Figure 10 Unsigned integer encoding in bitstream format (1 byte)|byte
2nd byte
i3rd byte
GB/T 14815.1-93
Operand value, 31
Operand value: 2079
Unsigned integer length: 2
Figure 11 Unsigned integer encoding in bitstream format (byte)
3rd byte? Section
1st byte
Section 22
6.3.2 Signed integers
Signed integers are represented using modulus and sign notation or two's complement notation. In both cases, they can be encoded in basic format or bitstream format.
Signed integers are represented as a sequence of single or multiple bytes. The data bits are loaded into each byte consecutively, starting with the high bit of the first byte of the most significant part of the operand.
6.3.2.1 Signed integers in modulus and sign notation using basic format The signed integer area is divided into a non-negative area and a negative area. The first byte, bit b, is used as the sign bit. If: a. h is "o\, then the integer is non-negative; b. If h is "1\, then the integer is negative. Positive zero is considered non-negative.
The encoding of negative zero is limited to: specific encodings. Signed integers are not allowed to have negative zero values. The bits b to b, in the first byte and the bits b, to b, in the following bytes are used to encode the modulus of the signed integer. Figure 12 contains an example of encoding a signed integer. GB,T 14815.1-93
Number effective value: 2
Operand value: 256
1st section
Second section
Figure 12 Signed integers in the two's complement notation using the base format 6.3.2.2 Signed integers in the two's complement notation using the base format The area of ​​the signed integer is divided into a non-negative area and a negative area. The first byte b.The bit will be used as the sign bit, that is: nt, bit 1\o", then the number is non-negative, b, 1\, then the number is negative
Negative numbers are represented in two's complement.
Positive integers are treated as non-negative.
The encoding of negative zero is limited to specific encodings. Signed integers do not allow negative zero values. Figure 13 contains an example of the encoding of signed integers in two's complement notation using the basic format. ha
Operand count: +?
Operand value: -50
1st byte
2nd byte
Figure 1, signed integer encoding using two's complement notation in base format 6.3.2.3 Modulo notation using bitstream format The number of bytes used for the signed integer operand is determined by the signed integer length state variable. The signed integer area is divided into a non-negative area and a negative area. The first byte is used as the sign bit, that is!
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