How to do a good job in print quality control in t

How to do a good job in print quality control in the digital environment (Part 1)

print quality refers to the comprehensive effect of various appearance characteristics of print. From the perspective of reproduction technology, the printing quality should be based on the faithful reproduction of the original. Whether in the traditional printing process or in the digital process, the printed matter should be faithful to the reproduction of the original

printing quality control elements

there are four control elements for printing: color, level, sharpness and consistency

1. Color

color is the basis of product quality, which directly determines the quality of products. Color control or management has always been a key link in the research and analysis of printing professionals

2. Level

refers to the gradient, which refers to the change of the recognizable color gradient of the image. It is the basis of accurate color reproduction

3. Sharpness

sharpness refers to the sharpness of image details, including three aspects: the sharpness of image fine levels, the sharpness of image contour edges and the sharpness of image details

4. Consistency

consistency is uniformity, which includes two aspects, such as aluminum alloy and HTC one s called "micro arc oxidation technology". On the one hand, it refers to the consistency of ink volume in different parts of the same batch of printed matter, that is, different ink areas. Generally, it is measured by the consistency of vertical and horizontal field density of printed matter. It reflects that the lower limit of printing printed at the same time will not be the stability of different parts of the zero. On the other hand, it refers to the consistency of the density of different batches of prints in the same part, which reflects the stability of the printing press

for printed matter, as long as these four aspects are well controlled, that is, the color, level, clarity and consistency of printed matter can be well controlled, high-quality printed matter can be obtained

printing quality control method

one of the methods of printing quality control is to use conventional signal strips, test strips, control strips, ladders, together with testing instruments and charts, to scientifically and quantitatively control the printing quality (including the quality of printing materials and the quality of printing engineering). At present, there are many kinds of signal strips and test strips used in various countries, such as GATF system in the United States, Bruner system in Switzerland, freguer system in Germany, and gelinda system. China mostly adopts the signals and test strips of GATF and Bruner, Switzerland

commonly used detection tools for printing include signal strip, test strip, control strip and ladder. The signal bar is mainly used for visual evaluation. Its function is relatively simple, and it can only express the appearance quality information of printed matter. Such as exposure ladder, GATF code signal strip, color signal strip, etc. The test strip is a multi-functional marking element based on densitometer detection and evaluation, which combines visual identification with densitometer testing, and carries out numerical calculation with the help of charts and curves. The control strip is the visual evaluation and measurement quality inspection of the signal strip and test strip; Metallurgical steel; Machinery manufacturing; Colleges and universities; Institute of scientific research and experiment; Commodity inspection, arbitration and technical supervision departments; A multifunctional control tool combined with other industry evaluations. Such as Bruner's third generation control strip. A ladder with equal differential density or points, which is used to control the printing quality

the printing process mentioned above needs to use signal strips and control strips to record data in the operation of its main links, so as to lay a foundation for standardized production. Quality inspection and control usually find problems through proofing. In the traditional printing process, traditional proofing is used, that is, proofing by round flattening. In the digital process, digital proofing has gradually replaced the traditional proofing. The digital documents to be printed can be directly output to the proofing machine, so as to see whether there are problems with words, specifications, images, etc. Since film and even printing plates are no longer used in the digital process, the quality evaluation and control largely depend on the successful development of a new type of nanocomposite digital proofing by the scientific researchers of the Academy. Then, in today's digital and networking environment, what factors restrict the printing quality in the digital process

what are the difficulties and advantages of quality inspection and control

methods of printing quality detection and control in digital environment

1 The transmission of data flow in the digital process

the digital production process makes the data flow and control flow in the actual production less intuitive than the traditional process. What we see is only the input layout elements, the layout information displayed by the display device, and the final output color digital proofing and CTP printing plate. Its operation information exists in the form of data. Any small error or small error will cause the failure of data transmission or abnormal output results, and will exceed the control ability of the operator. It is difficult or impossible to check the problem at all. Therefore, these variables have become uncontrollable factors in the prepress operation. In order to ensure the correct and smooth flow of data, we must find a set of practical data flow control methods

in the production of printing industry, there are two kinds of information flows in printing parts, namely, graphic information flow and production control information flow. Graphic information flow solves the problem of what to do; The control of information flow solves the problem of how to do and what to do. In the digitalization process, these two kinds of information are digitalized, which can be stored, recorded, processed and transmitted by computers. The control nodes of data flow in the digital process are document pre inspection, print output, PDF standardized digital collage, and rip post output

2. Color management under open system

color reproduction is an important measure of image reproduction quality. The color control in the traditional process is based on the theory of the definition and description of color attributes with density control as the core, and carries out color recognition and correction through a closed-loop system. The specific control methods include gray balance, color correction, optimal printing density control, point transfer and its control, etc

digital printing process is an open system. Input, processing and output equipment may come from different manufacturers. All kinds of devices have different ways of describing and expressing colors, and the same device will also suffer loss with the increase of use times, and the expressiveness of colors will also vary, which increases the difficulty of color reproduction. And because of the emergence of networks and the need of information exchange, the designed color images or color image files are no longer limited to local publishing and printing; Often need to watch or copy in different places. The color information of color image not only needs to be transmitted in different devices, such as computer monitors (even the same device, the ability of color display of devices produced by different manufacturers is also different), but also needs to be transmitted between different media

this requires a system whose function is to make the transmission results of colors between all media basically consistent without aliasing. That is, what you see is what you get. This system is called color management system. The international color organization ICC has developed a standard iccprofile to describe the color performance of devices. Using iccprofile feature files can realize cross platform color communication, so that when other computers add color management functions, these files can be converted at will. Color management is carried out through property files. Color management system is an application system, including computer hardware, computer software and color measuring equipment. Its goal is to form an environment so that various devices and materials supporting this environment can match each other in color information transmission and realize undistorted transmission

the new color control method with color space transformation as the core color management makes the technical process in the field of printing and communication enter a new digital production stage, and solves many problems of color benchmark and conversion in the production of printing media. New technologies and equipment such as digital proofing, CTP, digital printing and digital production process continue to appear, and move towards the goal of what you see is what you get

3. Data transmission and management

with the deepening of digitization, the amount of data increases exponentially