Traditional print inspection technology

Traditional print inspection techniques include subjective visual inspection, density inspection, and colorimetric detection.
Subjective visual inspection refers to the human comparison of prints and standard prints, either directly or with the aid of a magnifying glass, to subjectively assess the quality of prints. Although this method is simple and flexible, it is susceptible to the operator's experience and psychological, physiological and other factors, and the accuracy and stability are poor.
The density detection method and the colorimetric detection method use the instrument to measure the density and the color of the printed product, and use the relevant theory to analyze and process the data, and then evaluate the quality of the printed product.
Both of these methods can provide a theoretical basis for objectively evaluating the quality of printed products, overcome the instabilities of subjective visual inspection methods, and have a wide range of applications in the printing field. However, the instruments used for density and colorimetric detection can only detect areas around 10mm2. Therefore, it is necessary to add measurement and control strips to obtain the information we require from the print screen completely and directly. Moreover, related research shows that there are certain inaccuracies and limitations in the theory based on density and colorimetry.
The traditional printing inspection technology also has a common defect: they are all after the completion of the printing of the sample inspection, once the print quality problems, it is often several hundred, may even reach thousands, can not be found in the printing process Problems, resulting in waste of printed materials and working hours, increase production costs.
Due to many deficiencies of the traditional detection technology, on-line printing inspection technology came into being.