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<\/p>\nPDF-417 barcodes are a common type of 2-D barcode and are designed to store more data than a 1-D barcode with built in redundancy and error correction. A PDF-417 barcode actually consists of stacks of 1-D barcodes arranged in columns. Each of the 1-D barcodes is called a cluster and has a numeric value. The barcode shown below is a typical example – it has 4 columns and each column contains 12 clusters.<\/p>\n
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Some of the clusters contain information about the structure of the barcode or the row number, some are used for error correction and the rest hold the data. PDF-417 barcodes can be encoded with different levels of error correction – higher levels give better resillience against damage but also need more clusters and so can lead to larger, more complex barcodes.<\/p>\n
When a PDF-417 barcode is scanned at a low resolution it becomes harder for barcode scanning software to calculate the value for each cluster, which means that more error correction needs to be done. After a certain point it will not be possible to error correct and a barcode will fail to read. In a batch of PDF-417 barcodes scanned at a low resolution there will be some that read ok and others than will not.<\/p>\n
As a general rule it is best to ensure that each column of a PDF-417 barcode occupies at least 50 pixels in the scanned image and preferably around 70 pixels. \u00a0It’s also a good idea to avoid encoding any more data than is stricly necessary and to use the highest error correction level possible without impacting on the size of the barcode.<\/p>\n","protected":false},"excerpt":{"rendered":"
PDF-417 barcodes are a common type of 2-D barcode and are designed to store more data than a 1-D barcode with built in redundancy and error correction. A PDF-417 barcode actually consists of stacks of 1-D barcodes arranged in columns. Each of the 1-D barcodes is called a cluster and has a numeric value. The<\/p>\n