GB/T 18284-2000QR Code (English PDF)

3.1 Alignment pattern

A fixed reference pattern that is used to determine the position of the matrix symbol.

In the case of a certain degree of damage to the image, the decoding software can use it to synchronize the coordinate map of the image module.

3.2 Character count indicator

A bit sequence that indicates the length of the data string in a certain mode.

3.3 ECI designator

A 6-digit number that is used to identify a specific ECI task.

3.4 Encoding region

The area in the symbol that is not occupied by functional pattern and is used to encode data or error correction codewords.

3.5 Extended Channel Interpretation (ECI)

In some symbology, protocols that allow different interpretations of the output data stream and the default character set.

3.6 Format information

A functional pattern containing the error correction level used by the symbol and the mask pattern information, which is used to decode the remaining part of the encoding region.

4.1 Mathematical operators

The mathematical operators used in this Standard are defined as follows.

div. is the integer division operator;

4.2 Module positions

For ease of reference, module positions are defined by their row and column coordinates in the symbol, in the form (i, j) where i designates the row (counting from the top downwards) and j the column (counting from left to right) in which the module is located, with counting commencing at 0.Module (0, 0) is therefore located at the upper left corner of the symbol.

4.3 Byte notation

Byte contents are shown as hexadecimal values.

4.4 Version references

Symbol versions are referred to in the form Version V-E where V identifies the version number (1 ~ 40) and E indicates the error correction level (L, M, Q, H).

5.1 Basic characteristics

5.2 Additional features

5.3 Symbol structure

Each QR Code symbol shall be constructed of nominally square modules set out in a regular square array and shall consist of an encoding region and function patterns, namely finder patterns, separator, timing patterns, and alignment patterns.

5.3.3 Separators

A one-module wide Separator is placed between each Position Detection Pattern and

Encoding Region, as illustrated in Figure 2, and is constructed of all light modules.

5.3.4 Timing Pattern

The horizontal and vertical Timing Patterns respectively consist of a one module wide row or column of alternating dark and light modules, commencing and ending with a dark module (as illustrated in Figure 2). The horizontal Timing Pattern runs across row

6 of the symbol between the separators for the upper Position Detection Patterns; the vertical Timing Pattern similarly runs down column 6 of the symbol between the separators for the left-hand Position Detection Patterns. They enable the symbol density and version to be determined and provide datum positions for determining module coordinates.

5.3.5 Alignment Patterns

Each Alignment Pattern may be viewed as three superimposed concentric squares and is constructed of 5 × 5 dark modules, 3 × 3 light modules and a single central dark module (as illustrated in Figure 2). The number of Alignment Patterns depends on the symbol version and all symbols of Version 2 above (including Version 2) have the alignment patters, see Annex E in detail.

5.3.6 Encoding region

This region shall contain the symbol characters representing data codeword, those representing error correction codewords, the Version Information and Format

Information. Refer to 6.7.1 for details of the symbol characters. Refer to 6.9 for details of the Format Information. Refer to 6.10 for details of the Version Information

5.3.7 Quiet zone

The quiet zone is a 4 module-wide zone surrounding the symbol, its nominal reflectance value shall be equal to that of the light modules.

6.1 Encode procedure overview

6.2 Data analysis

Analyze the input data string to determine its content and select the default or other appropriate ECI and the appropriate mode to encode each sequence as described in

6.3 Modes

The modes defined below are based on the character values and assignments associated with the default ECI. When any other ECI is in force, the byte values rather than the specific character assignments shall be used to select the optimum data compaction mode. For example, Numeric Mode would be appropriate if there is a sequence of data byte values within the range 30HEX to 39HEX inclusive. In this case the compaction is carried out using the default numeric or alphabetic equivalents of the byte values.

6.3.1 Extended Channel Interpretation (ECI) Mode

The Extended Channel Interpretation (ECI) protocol allows the output data stream to have interpretations different from that of the default character set. The ECI protocol is defined consistently across a number of symbologies. Four broad types of interpretation are supported in QR Code.

6.3.2 Numeric Mode

Numeric mode encodes data from the decimal digit set (0 ~ 9) (ASCII values 30HEX to

39HEX) at a normal density of 3 data characters per 10 bits.

6.3.4 8-bit Byte Mode

The 8-bit byte mode is used to represent ASCII character set (character values 00HEX to FFHEX). In this mode data is encoded at a density of 8 bits/character.

6.3.5 China-Chinese Mode

The China-Chinese mode handles two-byte China-Chinese characters and non-

Chinese characters specified in GB 2312, its character value is the internal code values corresponding to the characters specified in GB 2312, see GB 18030.Each two-byte character value is compacted to a 13-bit binary codeword.

6.3.6 Mixing modes

The QR Code symbol may contain sequences of data in a combination of any of the modes described in 6.3.1 to 6.3.5.

Refer to Annex H for guidance on selecting the most efficient way of representing a given input data string in Mixing Mode.

6.4 Data encoding

Input data is converted into a bit stream consisting of an ECI header if the initial ECI is other than the default ECI, followed by one or more segments each in a separate mode.

In the default ECI, the bit stream commences with the first Mode Indicator.

The ECI header (if present) shall comprise.

6.4.1 Extended Channel Interpretation (ECI) Mode

This mode, adopted for encoding data subject to alternative interpretations of byte values (e.g., alternative character sets) in accordance with the AIM ECI specification which defines the pre-processing of this type of data, is invoked by the use of Mode

Indicator 0111.

6.4.6 Mixing modes

There is the option for a symbol to contain sequences of data in one mode and then to change modes if the data content requires it, or in order to increase the density of encoding. Refer to Annex H for guidance. Each segment of data is encoded in the appropriate mode as indicated in 6.4.1 to 6.4.5, with the basic structure Mode

Indicator/Character Count Indicator/Data and followed immediately by the Mode

Indicator commencing the next segment. Figure 10 illustrates the structure of data containing n segments.

6.4.7 FNC1 Modes

There are two mode indicators, which are used in conjunction with the mode flags specified in 6.3.1 to 6.3.8 and 6.4.1 to 6.4.6 to identify symbols that indicate information formatted according to a specific industry or application. They (together with relevant parameter data) are placed before the mode indicator. If the FNC1 mode is used, the decoder must transmit the symbol identifier as specified in 12.1 and Annex F.

7.1 Basic principles

Up to 16 QR Code symbols may be appended in a structured format. If a symbol is part of a Structured Append message, it is indicated by a header block in the first three symbol character positions.

The Structured Append Mode Indicator 0011 is placed in the four most significant bit positions in the first symbol character.

7.2 Symbol Sequence Indicator

This codeword indicates the position of the symbol within the set of (up to 16) QR Code symbols in the Structured Append format (in the form m of n symbols). The first 4 bits of this codeword identify the position of the particular symbol. The last 4 bits identify the total number of symbols to be concatenated in the Structured Append format. The

4-bit patterns shall be the binary equivalents of (m - 1) and (n - 1) respectively.

7.3 Parity Data

The Parity Data shall be an 8-bit byte following the Symbol Sequence Indicator. The parity data is a value obtained by XORing byte by byte the ASCII values of all the original input data before division into symbol blocks. Mode Indicators, Character

Count Identifiers, padding bits, Terminator and Pad Characters shall be excluded from the calculation. Input data is represented for this calculation by 2-byte internal code values for China-Chinese (each byte being treated separately in the XOR calculation) and 8-bit ASCII values as shown in Table 6 for other characters.

8.1 Dimensions

QR Code symbols shall conform to the following dimensions.

X dimension. the width of a module shall be specified by the application, taking into account the scanning technology to be used, and the technology to produce the symbol;

Y dimension. the height of a module shall be equal to the width of the module.

Minimum quiet zone. equal to 4X on all four sides.

8.2 Human-readable interpretation

Because QR Code symbols are capable of encoding thousands of characters, a human readable interpretation of the data characters may not be practical. As an alternative, descriptive text rather than literal text may accompany the symbol.

8.3 Marking guidelines

QR Code symbols can be printed or marked using a number of different techniques.

Annex I provides user guidelines.

9.1 Obtaining the test image

A grey-scale image of the symbol being tested shall be obtained with a precision video camera-based setup as described in Annex J1, but with an illumination color and direction specified by the application.

9.2 Symbol quality parameters

9.2.1 Decode

The reference decode algorithm set out in Clause 11 shall be applied to the test image.

If it results in a successful decode of the entire data message, then Decode passes with a grade of 4 ("A"), otherwise it fails with a grade of 0 ("F").

9.2.2 Symbol Contrast

Symbol Contrast shall be graded using all of the grey-scale pixel values in the test image which fall within the symbol's boundary, including the 4X wide quiet zones, as determined by the reference decode. The procedure is defined in Annex J2.2.

9.2.3 "Print" growth

The reference decode begins by creating a high resolution binary digitized image of the test symbol, and at a later point establishes the position of the "alternating module centerlines" which bisect the Timing Patterns of the symbol. "Print" Growth shall be assessed by checking that the "duty cycle" of the lines through the alternating patterns is around 50%.

9.2.4 Axial Nonuniformity

The reference decode algorithm ultimately creates a grid of data module sampling points throughout the entire area of the test image. The precise horizontal and vertical spacings of those sampling points are the basis for assessing axial nonuniformity.

Working independently with the horizontal and vertical spacings between adjacent data modules, compute their average values XAVG and YAVG over the whole symbol.

The Axial Nonuniformity grade is then based on how closely these two average spacings match each other, as computed by the procedure defined in Annex J2.4.

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