Page History: Datamatrix (2D-Barcode)
Compare Page Revisions
Page Revision: 2010/06/26 21:55
Principle of Datamatrix Barcodes
Datamatrix (or Data Matrix) is a high density 2 dimensional barcode that can encode up to 3116 characters from the entire 256 byte ASCII character set. Compared with DF417 barcode symbology the datamatrix barcode belongs to newer family of 2 dimensional barcodes that makes better use of both dimensions and thus can achieve higher data capacity than the PDF417 symbology (~3kB vs ~2kB). The symbol is built on a square grid which have a finder pattern around the edges of the symbol to allow a scanner to identify the barcode. The finder pattern makes it possible to read the barcode regardless of the physical orientation of the code.
In the same way as with other 2 dimensional barcodes the datamatrix code includes error correction capability in order to be resilient towards physical damages of a code. Originally data matrix used an older convolutional error correction schema (ECC) but that has later been changed to use a Reed-Solomon type of error correction which is much more efficient. The older ECC version is known as ECC 000 to ECC 140 and should be considered obsolete and should not be used in new applications.
The newer error correction schema (with Reed-Solomon codes) is known as ECC 200 schema and is the current and recommended schema. By default the library will use the newer schema but support also exists for legacy applications to use the older ECC schema. (See ??)
The image shows an annotated Datamatrix where the finder and synchronization patterns have been highlighted.