Research On 2D Bar Code Quality Detection Technology Based On Machine Vision

Two-dimensional bar codes are graphic symbols distributed on a plane with specific geometric figures to record data information.They can realize automatic processing of information through reading equipment,and are widely used in production and distribution,logistics tracking,e-commerce,network security and other fields.With the rapid development of information technology and the increasing popularity of intelligent terminal devices,the application of two-dimensional barcodes is becoming more and more extensive and in-depth.The quality of two-dimensional barcodes is crucial for the reading and application of two-dimensional barcodes.Our country has promulgated the inspection standard for the quality of two-dimensional barcode symbols(GB/T 23704-2009),and has formulated relevant specifications and standards for the quality inspection of two-dimensional barcodes.At present,there are few general-purpose instruments that can be used for quality inspection of two-dimensional barcodes.Only a few foreign-made inspection instruments can detect some quality parameters of two-dimensional barcodes.Domestic research and application of two-dimensional bar code quality testing is still in its infancy.This article takes QR code as the research object,adopts machine vision detection technology,and implements the quality inspection of the two-dimensional bar code based on the inspection standards and specifications of the printing quality of the two-dimensional bar code symbol.The main work of this article includes the following aspects:First,the collection of QR code images.Use the barcode image acquisition device to collect the QR code image to be tested and transfer the barcode image to the computer for subsequent processing.In order to use the computer to control the bar code image acquisition device,this paper has carried out programming design such as data interface and camera control.Second,the positioning and division of the QR code area.The collected barcode image includes the QR code barcode area and other backgrounds,and the quality inspection is directed to the QR code area,so the barcode area must be segmented from the entire image in order to find and segment the barcode area for the QR code.This article preprocesses the barcode image,including image graying,image binarization,etc.;using three position detection patterns to locate the barcode area,the barcode area is initially segmented according to the block characteristics,and then combined with morphological processing to obtain The part of the barcode is connected to the domain,and the QR code area is accurately segmented again;according to the coordinates of the center point of the position detection graphic,the tilt angle can be obtained,and the correct barcode image can be obtained by using rotation correction.Third,the analysis and calculation of the QR code area image.For the barcode area image,according to the position detection pattern,correction pattern and module width,a sampling grid point is established,and according to the shade of the grid,a new bitmap is established,and finally a matrix representing QR code symbols is formed.Analyze and calculate the sign contrast,modulation ratio,axial inconsistency,grid inconsistency and inherent graphic contamination detection parameters.Decode the QR code to extract data information.According to national standards,the quality judgment parameters are graded to form a conclusion.In this paper,50 QR code samples were collected and tested.All of them were able to complete the quality inspection and measured all the test data.The same sample was placed in different positions and angles for multiple inspections,and the inspection data was highly consistent.The experiment proves that the method in this paper is simple in operation,fast in detection speed,and has high accuracy and stability.