As one of the main ways to store, spread, exchange information and spread culture, the quality of printing is an important link in the production and management of publishing and printing enterprises. There are many factors that affect the evaluation results of text printing quality, such as ink density, clear contrast, and whether the pen is broken or not. All the time, the evaluation of these indicators is carried out by human vision. Such detection method has been unable to meet people's requirements for efficiency and quality, technology update to be solved.

Under this situation, to achieve the rapid detection of the printing quality and the improvement of the objective evaluation index for testing and evaluation of the human eye to text printing quality limitation, industry and introducing the technology of machine vision, image processing, pattern recognition, testing and evaluation of text printing quality, great solved this problem.

Because the machine vision technology has great superiority, can quickly get a lot of information, and easy to automatic processing, also easy to design information and process control information integration, therefore, in modern automated production process, people will be widely used in machine vision system condition monitoring, inspection and quality control, etc. The online quality inspection system of text printing based on machine vision system greatly improves the quality and efficiency of book printing, and reduces the production cost.

Machine vision industrial inspection system can be divided into quantitative and qualitative inspection in terms of its inspection nature and application scope. Machine vision is widely used in various application fields of industrial online inspection. For EXAMPLE, VISUAL inspection OF printed circuit BOARDS, AUTOMATIC flaw detection of steel plates, PARALLELism and VERTICality measurement of large workpieces, container volume or impurity detection, automatic identification and classification of mechanical parts and geometric size measurement, etc. In addition, in many cases where other methods are difficult to detect, machine vision system can be effectively implemented. The application of machine vision is increasingly replacing people to complete a lot of work, which undoubtedly improves the level of production automation and detection system intelligence to a great extent.

Based on the machine vision system, it can also identify and detect the spray coded text. Firstly, the features such as font contour, grid and projection are extracted, and then, according to the statistical features, the local features of the inner edge are extracted for the second judgment. This method has achieved good results in industrial application. Such based on machine vision technology, there are many applications in text printing, character detection, spray coding text defect detection, fully reflects the advantages of machine vision technology.