About Stacked & 2D Codes

Axicon European Reseller ConferenceMartin Morrison

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GS1 Barcodes

• GS1 have limited the number of barcode types that can be used to carry GS1 formatted data and for many years this meant that only EAN/UPC, ITF-14 or GS1-128 linear barcodes could be used

• 15 years ago a new family of linear barcodes was introduced that had been designed specifically to carry GS1 data

• Designed to be used on consumer unit items that would be scanned at retail point of sale, the GS1 DataBar codes are able to be scanned with omnidirectional laser scanners and are smaller than equivalent EAN/UPC or GS1-128 codes

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GS1 DataBar

• Despite the advantages that GS1 DataBar codes have, there has been little uptake in the retail industry so far

• They have been used extensively on pharmaceutical products in North America, although GS1 DataMatrix may displace them in this sector in the future

• The GS1 DataBar Expanded version has also been used on coupons in North America

• The Expanded version does have some potential for carrying additional data to the point of sale, but many retailers are still only able to process GTIN data through their point of sale systems

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GS1 DataBar Structure

• GS1 DataBar codes are structured with data segments or triplets which can be scanned independently

• The green and blue areas are finder patterns with data characters on each side of these patterns

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Ability to stack GS1 DataBar

• Triplets can be split and stacked, as shown below

• A separator pattern is then inserted – it contains no information but helps scanners determine when scan lines cross from one row to another

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GS1 DataBar Expanded

• The GS1 DataBar Expanded code has a variable length capability and is designed to carry elements strings that incorporate applications identifiers

• Unlike GS1-128 codes, which simply grow longer as more data is encoded, the Expanded code can be stacked with up to 11 rows making it more compact

• Encoding - (8110)106141410012342501106501013085093101231

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2D Matrix codes

• There are now two 2D Matrix codes that can be used within the GS1 system

• GS1 DataMatrix has been used for a number of years but there is also now the possibility to use GS1 QR codes for certain applications (not healthcare)

• With both of these codes it is necessary to identify that they are carrying GS1 formatted data

• In the case of GS1 DataMatrix a special function 1 codeword is encoded at the beginning of the data string just like with GS1-128 codes

• With GS1 QR codes the encodation mode signifies that it conforms to GS1 rules and data format

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Data Matrix finder patterns

• The finder patterns for Data Matrix consist of an ‘L’ pattern and clock tracks that surround the data encoding modules

• Larger symbols that contain more data can require extra alignment patterns

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QR code finder patterns

• QR codes have three finder patterns and additional alignment patterns depending on the amount of data

• Micro QR code

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Data is encoded in modules

• Codewords, consisting of 8 modules, encode data and error correcting capability

• These codewords do not correspond directly to numeric digits or alphabetic characters

• The codeword modules are not always in continuous adjacent blocks

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Comparing matrix codes

• The differences between QR and Data Matrix codes are fairly minor from the point of view of encoding data efficiently

• There are various applications of both code types across many different printing and scanning environments

• Healthcare applications around the world are now becoming dominated by the use of GS1 DataMatrix

• QR codes have become the most common way to encode web site links and there is considerable support for scanning QR codes on smart phones

• Retail manufacturers are beginning to use both

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Data Matrix options

• One possible benefit for certain product shapes with Data Matrix is its option to encode data in a rectangular format – QR codes are always square in shape

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Imaging matrix codes

• 2D Matrix codes cannot be decoded with conventional laser scanners

• Imaging camera scanners must be used and presently not many retail point of sale scanners use this technology

• Some slot scanner manufacturers have developed hybrid scanners that incorporate both scanning laser and imaging camera scanners, so as these become the standard at point of sale then matrix codes could start to replace existing linear barcodes

• Point of sale systems will still need to be upgraded in order to make use of additional encoded data

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Verification method for 2D codes

• The method of verifying 2D matrix codes is quite different to the method used for linear barcodes

• With linear barcodes we measure the dimensions between bar edges in order to calculate decodability

• With matrix codes we find the centres of modules by establishing a grid of lines that intersect where module centres should be

• Reflectance measurements are then made at grid intersections in order to grade modules

• Damaged codes are also graded by checking how much error correction is required in order to decode

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Verification method for 2D codes

• Codes that are made with circular modules can still get a good grade even though modules should be printed nominally square

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Verification method for 2D codes

• When some of the modules are covered up, it is still possible to decode using error correction but the grade is lower

• Grade 1 (D)• UEC 25%