Example of DotCode
DotCode is a two-dimensional (2D) matrix barcode invented in 2008 by Hand Held Products as a replacement for the outdated Code 128. At this time, it is issued by Association for Automatic Identification and Mobility (AIM) as “ISS DotCode Symbology Specification 4.0”. DotCode consists of sparse black round dots and white spaces on white background. In case of a black background the dots can be white. DotCode was developed to be used with high-speed industrial printers where printing accuracy can be low. Because DotCode by the standard does not require complicated elements like continuous lines or special shapes it can be applied with laser engraving or industrial drills.
DotCode can be represented as rectangular array with minimal size of each side 5X dots. Maximal size of DotCode is not limited by the standard (as Code 128 is not limited) but practical limit is recommended as 100x99 which can encode around 730 digits, 366 alphanumeric characters or 304 bytes.
As an extension of Code 128 barcode, DotCode allows more compact encoding of 8-bit data array and Unicode support with Extended Channel Interpretation feature. Additionally, DotCode provides much more data density and Reed–Solomon error correction which allows to restore partially damaged dotcodes. However, the main DotCode implementation, the same as Code 128, is effective encoding of GS1 data which is used in worldwide shipping and packaging industry.
DotCode symbol structure
DotCode symbol is constructed from the following elements:
- Two mask bits which are represented on diagram as two green points;
- Data bits (data and error correction bits) which must be read from up to down (even barcode side) and from left to right (odd barcode side);
- Corner points, marked as red on diagram, which can be used as data bits or padding bits (black dots);
- Quiet zone at least 3X size of the dots.
The DotCode bits array is represented as:
(Two mask bits: M2, M1)(Data bits)(Corner bits, can be data or padding bits: C1 – C6)
The data codewords in 0 – 112 range are encoded in 5-of-9 binary dot patterns which are encoded from 9 dots where 5 black dots and 4 white spaces. The rest of barcode matrix (rest from division on 9) is padded with black padding bits. The padding bits can be from 0 to 8. The logically DotCode bits array is represented as:
(2 mask bits)(Data codewords 9 bits each)(Padding bits 0 – 8 bits)
DotCode size has the following requirements:
- Sum of DotCode width and height must be odd: 𝔽113 or GF(113). The data codewords is represented with values from 0 to 112 and mask value is counted as leading data codeword from 0 to 3. In this way the data protected array length is (1 + ND). But amount of error correction codewords is calculated only from ND:
B=(NW+111)/112,
where B is block counts.The data can be split into block in the following way, for each block ‘’’n’’’, for n equals 1 to B:
- NC(block)=NW(block)−ND(block)
The error correction data |
124 92 111010001 36 D 68 D 68 36 010100111 93 GS 29 } 125 93 000101111 37 E 69 E 69 37 010110011 94 RS 30 ~ 126 94 000110111 38 F 70 F 70 38 010111001 95 US 31 DEL 127 95 000111011 39 G 71 G 71 39 011001011 96 Shift B CR/LF 13/10 96 000111101 40 H 72 H 72 40 011001101 97 2x Shift B HT * 09 97 001001111 41 I 73 I 73 41 011010011 98 3x Shift B FS * 28 98 001100111 42 J 74 J 74 42 011011001 99 4x Shift B GS * 29 99 001110011 43 K 75 K 75 43 011100101 100 5x Shift B RS * 30 (17)...(10) 001111001 44 L 76 L 76 44 011101001 101 6x Shift B Shift A Latch A 010001111 45 M 77 M 77 45 100101110 102 Latch B Latch A Shift B 011000111 46 N 78 N 78 46 100110110 103 2x Shift C 2x Shift C 2x Shift B 011100011 47 O 79 O 79 47 100111010 104 3x Shift C 3x Shift C 3x Shift B 011110001 48 P 80 P 80 48 101001110 105 4x Shift C 4x Shift C 4x Shift B 100011110 49 Q 81 Q 81 49 101011100 106 Latch C Latch C Latch B 100111100 50 R 82 R 82 50 101100110 107 FNC1 FNC1 FNC1 101111000 51 S 83 S 83 51 101101100 108 FNC2 FNC2 FNC2 110001110 52 T 84 T 84 52 101110010 109 FNC3 FNC3 FNC3 110011100 53 U 85 U 85 53 101110100 110 Upper Shift A Upper Shift A Upper Shift A 110111000 54 V 86 V 86 54 110010110 111 Upper Shift B Upper Shift B Upper Shift B 111000110 55 W 87 W 87 55 110011010 112 Binary Latch Binary Latch Binary Latch 111001100 56 X 88 X 88 56 110100110 * in lead data positions, these become “Macros” There three main rules at message encoding start:
- The default starting encoding is Code Set C;
- In case of two digits in Code Set C (0 – 100 value) are encoded in the position of the first codeword, the message is decoded as GS1 message;
- If FNC1 (opposite effect to Code 128) or other non-digit codeword (101 - 112) is encoded in the position of the first codeword, the message is decoded as NON GS1 message.
Binary byte encoding
editDotCode can encode full 8-bit charset in two ways:
- With Upper Shift, which requires 2 codewords on one (128 to 255) symbol;
- With Binary Latch, which requires 1 Binary Latch symbol and 6 codewords on every 5 bytes.
Upper Shift modes can encode (128 to 255) extended ASCII characters in two codewords with returning to previous mode:
DotCode Upper Shift encoding Upper Shift Type Codewords ASCII Upper Shift A 64 to 95 128 to 159 Upper Shift B 0 to 95 160 to 255 Binary Latch mode can encode 8-bit charset and ECI sequences from 1 to 5 symbols. It uses the following rules:
- The data is split into block of 5 symbols (byte or ECI mode identifier) or 6 codewords;
- 0 – 258 values are radix converted from five base 259 into six base 103 values;
- 0 – 255 values are byte values;
- 256, 257 or 258 values marks to encode ECI sequence in next 1, 2 or 3 bytes respectively;
- Any DotCode codewords in the encoded sequence above 102 (from 103 to 112) interrupt or change mode.
DotCode Binary mode non-data codewords Codeword Operation 103 Interrupt for 2x Shift C 104 Interrupt for 3x Shift C 105 Interrupt for 4x Shift C 106 Interrupt for 5x Shift C 107 Interrupt for 6x Shift C 108 Interrupt for 7x Shift C 109 Terminate with Latch to A 110 Terminate with Latch to B 111 Terminate with Latch to C 112 Terminate with Symbol Separation, Latch to C As we see in the following table, Binary Latch encodes data more effectively, starting from 3 bytes.
DotCode Binary mode efficiency Bytes count Codewords required Codewords with latch and return required Upper Shift codewords required 1 2 4 2 2 3 5 4 3 4 6 6 4 5 7 8 5 6 8 10 ECI encoding
editDotCode can encode ECI indicator int two ways:
- In Binary Latch mode (reviewed upper);
- With FNC2 character.
FNC2 in any position except at the end of data signals the insertion of an ECI sequence – "\nnnnnn", which represents values between 000000 and 811799. The values can be encoded in 1 or 3 codewords:
- In case of next codeword < 40 directly encodes ECI value 000000 to 000039;
- Otherwise, the next three codewords valued A, B, & C encode an ECI value of ND=(NW−3)−(NW−3)/3
In this way we need to pad data codewords in case with have free space. There are two rules:
- Binary mode must be terminated with Latch to Code Set A (codeword 109);
- In other modes codeword 106 (Latch to Code Set C / Latch to Code Set B) must be used.
See also
edit- Automated identification and data capture (AIDC)
- Barcode
- Code 128
- Extended Channel Interpretation
- GS1
- Hand Held Products
References
edit- ↑ "Bar Code Technology : Matrix 2D Symbologies". aimglobal.org. Archived from the original on 2011-11-05.
- ↑ "Chinese Patent CN113297872A by Fuzhou Symbol Information Technology Co ltd "Dotcode identification method and equipment"". patents.google.com. China National Intellectual Property Administration. 24 August 2021. CN113297872A.
- ↑ "Revised 2D barcode offers potential in beverage, distribution, ecommerce markets". www.packagingdigest.com.
- ↑ "Generate DotCode Barcodes in C#". www.aspose.com.
- ↑ Category
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