From POS systems in supermarkets and convenience stores to production instruction systems in manufacturing, barcodes have been widely used across various industries worldwide. With the increasing prevalence of barcodes, the need for more functionality has arisen. These needs include allowing barcodes to have greater information capacity to store all relevant data, and the development of smaller barcodes for electronic components.
QR codes are specifically designed to meet these needs. A QR code can contain dozens of times more information than a barcode, while its size is only a fraction of that of a barcode. Because of these advantages, the application of QR codes is increasing in various fields.
1. Larger data storage capacity : Barcodes can only store information in one direction, while QR codes can use both vertical and horizontal directions to store information. This means that QR codes can store tens or even hundreds of times more data than barcodes.
2. High data density: With the same amount of data, the size of a QR code can be much smaller than that of a barcode.
3. Strong error correction capability: The QR code has a built-in error correction function that can recover data damaged by dirt or breakage. Even if 10% to 30% of the barcode area is damaged, the data can still be read normally.
Two-dimensional barcodes also have many different encoding methods, or code systems. In terms of their encoding principles, these code systems can generally be divided into the following two types:
1. Row-based 2D barcodes : Row-based 2D barcodes (also known as stacked 2D barcodes or layered 2D barcodes) are based on 1D barcodes, stacking them into two or more rows as needed. They inherit some characteristics of 1D barcodes in terms of encoding design, verification principles, and reading methods. Reading devices and barcode printing are compatible with 1D barcode technology. However, the decoding algorithms and software are not entirely the same as 1D barcodes. Representative row-based 2D barcodes include PDF417.
2. Matrix Two-Dimensional Barcodes : Matrix two-dimensional barcodes encode data using the different distributions of black and white pixels within a rectangular space. At corresponding element positions in the matrix, the presence of a dot (square, circle, or other shapes) represents a binary "1," while the absence of a dot represents a binary "0." The arrangement and combination of dots determine the meaning of the matrix two-dimensional barcode. Matrix two-dimensional barcodes are a new type of automatic graphic symbol recognition and processing code system based on computer image processing technology and combinatorial coding principles. Representative matrix two-dimensional barcodes include: Maxi Code, QR Code, and Data Matrix.
Among the various QR codes, Datamatrix codes and QR codes are currently the most popular in China, with QR codes being the most widely used due to their advantages such as fast reading speed, large information capacity, small space occupation, strong confidentiality, and high reliability. A QR code is square, uses only two colors, and has a small square pattern resembling the Chinese character "回" printed in three of the four corners. QR codes are an open standard; their specifications are public, and the inventor's patent rights are not enforceable.
Currently, QR code reading mainly adopts image-based reading. As an image processing technology, successful reading depends on two aspects:
Basic pixel requirements : Select the appropriate reader pixel size based on the size of the barcode, such as 360,000 pixels, 1.3 million pixels, or higher;
Image preprocessing techniques : Image preprocessing involves not only recognizing and identifying images, but also enhancing and weakening them.
During the QR code reading process, difficulties in reading are frequently encountered. This is mainly due to distortion and reflective factors of the printing medium, as well as partial damage to the QR code, as shown below:
To address these challenges in reading barcodes, Banner Engineering is about to launch two professional industrial barcode readers that, based on image processing technology, enable reliable reading of 1D or 2D barcodes:
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