The maturity and development of CTP technology has changed the production, management, and even the business model of printing and related industries to a large extent, creating new business opportunities and markets, and bringing many production benefits to the manufacturers that use them. It has become a magic weapon for enterprises to win in fierce competition. However, in the face of new technologies and new processes, due to the operator's experience and the limitations of the peripheral equipment itself, there are often problems that need our attention in practical work. At the same time, because of these problems, the advantages of CTP cannot be fully reflected, but it has hindered the improvement of enterprise production efficiency. The poor use of individual users has also caused a negative impact on the expansion of the CTP market. Therefore, managers engaged in CTP work must be proficient in technology, use a variety of management knowledge, coordinate the overall situation in the complicated and pre-press work, master and control the work process, and make the work proceed in an orderly manner.
1. Linearization of CTP Publishing
The color management in the CTP process is the focus and difficulty of the CTP technology. The ICC characteristic curve that accurately reflects the characteristics of the device determines the effect of color management. Therefore, the generation and application of the ICC characteristic curve have become the top priority of color management.
First of all, we know that the current purple laser CTP due to its photosensitive characteristics and the characteristics of the plate processor determines linearization is an indispensable part. Some users always have a skeptical attitude towards the linearization curve when using it, and they are not very confident about the accuracy of the device's linearity. After a lot of practice, this kind of worry is completely unnecessary. Some monitoring methods in the use process can fully guarantee the accuracy of the outlet restoration.
1. Environmental temperature and humidity control. In a safe photosensitive environment, strict control of temperature and humidity is very beneficial to the reproduction of CTP network points. Generally, it is necessary to ensure that the ambient temperature is around 23 and the humidity is between 50-60.
2. Precise control of PH value. The developer of the processor is changed regularly as required. The developer in the developer tank of the processor is measured before publication every day to ensure that the PH value of the developer is within 12 ± 0.25 at 28 ° C. If not enough, add supplemental fluid separately.
3. Measurement by plate tester. In order to verify the accuracy of the value of the published outlets, a gray ladder ruler can be attached to the bending position on the plate. After the printing is completed, the actual outlet value is measured to check the difference from the required value, but pay attention when measuring The compared value is the value after adding the inverse compensation curve.
After ensuring that there are no problems with the above three points, the obtained dot value is completely no problem. They have become an advantageous weapon for the restoration of control outlets.
Of course, when the PH value reaches a relatively stable state, it also needs a period of monitoring and adjustment. Due to the difference in the size and environment of the user's plate material, the period before installation may be a process of exploring the PH value. During this period of time, the real-time monitoring of the publication will be done, and we can find a suitable amount of supplemental liquid. Within a certain period of time, if the PH value does not change significantly during the publication process, it indicates that the adjustment has met the standard. The user can follow the hardware engineer to learn the adjustment skills, and can make adjustments if necessary.
Second, CTP publishing and printing compensation
Sometimes, users often put forward some ideas on the plate making process curve according to the needs of their products (such as black and blue small dots on the skin of the character album, the shadow and small dots such as jewelry albums, etc.), and take it to the traditional film. Contrast printing. Because the acquisition of the CTP process curve is a time-consuming, labor-intensive and cost-intensive process, it is basically obtained by printing test files, collecting data and making accurate measurements. The traditional film printing is only through simple addition Minor adjustments are made to the time-reduced printing plate. After repeated on-board testing and verification, although it may not necessarily achieve completely accurate results, customers believe that the timeliness is more obvious than CTP. As a result, it gradually entered a misunderstanding that the traditional film than CTP is convenient and practical.
Then we return to the root of the problem. It is not difficult to find that in fact all the requirements are based on an uncertain factor: they are deliberately adjusting the existing plate-making process according to their subjective ideas. We believe that "the character's skin color must be soft and rosy, and the jewelry shadow needs to be complete and delicate". These are deliberately related processing on the plate making without actual standards. However, have we noticed that the value of CMYK on the source file is far from the actual value of the site in the version? At the same time, due to the adjustments made by these uncertain factors, if the process parameters cannot be recorded in detail, the same job will be printed on the same machine after the next printing, and different results will be printed.
So what we need to do is to establish a different standard for different needs. No matter it is a normal operation specification or an abnormal process standard that needs to be changed intentionally, as long as there is relevant reference data, different process curves can be established. The newly established process curve is closely integrated with the computer and process software, and there will be no inconsistency in the output at different times, which can completely guarantee the accuracy and consistency of the outlets. Of course, in actual operation, it is not desirable to have too many process curves. Too many process curves are ultimately inconvenient to manage, and making process curves is also unrealistic in production.
At present, we are based on the international standard of ISO12647-2, the domestic standard of GB17934-2 and the actual printing situation in China to develop the CTP process curve with user characteristics. In order to occupy the quality advantage in the fierce competition, printing companies should actively pay attention to the standard Application, and strive to be in line with international standards in product quality management. [next]
3. CTP digital proofing
After the process curve is determined, a standard printing characteristic file is printed according to the standard, and the remaining work is to make a digital proof. After a series of measurement and production, once the digital proofing is printed, users can't help but worry. "This digital proofing is so beautiful, can the printing keep up?" At present, most users may still prefer the traditional flat proofing, but After understanding the traditional drawbacks, their views also changed.
1. Analysis of advantages and disadvantages of traditional proofing
The advantages of traditional proofing mainly include the following:
(1) The production process of the proofing plate and the printing plate is relatively close, in theory, it can better simulate the actual printing;
(2) The same rasterized data is used for proofing and printing. Potential problems such as moire, layout and fonts can be found through proofing. At present, digital proofing can also be done after RIP;
(3) When proofing spot and metallic colors, it performs well on trapping and ink opacity.
The disadvantages of traditional proofing are the following:
(1) High technical content, requiring professional technicians to obtain accurate proofs, and labor intensity;
(2) Higher investment is required, including the cost of film, printing plates, paper, and ink;
(3) There are many processes involved, the cost is high, and the processing cycle is also long.
2. Analysis of the advantages and disadvantages of digital proofing
The digital proofing technology is completely controlled by digitization, which has changed the previous complicated printing production process and reduced the cost at the same time. And the stability of plate making and printing quality has been greatly improved.
The advantages of digital proofing mainly include the following:
(1) No need to output film or make plate cylinder, which can reduce the cost while shortening the production cycle;
(2) Samples made based on inkjet technology are usually more stable in quality;
(3) Digital proofing is an important part of digital printing. Its unique stability can provide standards for the entire printing process and provide a strong guarantee for the improvement of printing quality.
The disadvantages of digital proofing are the following:
(1) Some digital proofing systems cannot ensure the integrity of document data, and proofing can be done after RIP;
(2) The digital proofing system with the function of processing mesh adjustment requires higher costs;
(3) Spot colors and metallic colors cannot be accurately reproduced, and a specific system must be used.
Of course, digital proofing is not completely close to the printed matter. The difference is mainly due to the difference in materials and imaging methods. In addition, although the digital samples converted based on the ICC principle match most of the colors, but due to part of the equipment, there may still be compression during the conversion of the super color gamut. The problem, but these cannot be avoided by any digital proofing software. Users also need to try to change the customer's concept and strive for cost savings and efficiency improvements.
3. Handling of color problems in digital proofing
Many times, because of the irregular processing of document pictures, the actual proofing color is different from the color that the customer feels. In this case, there must be a firm belief that digital proofing is no problem at all. Digital proofing is made with reference to the standard printing characteristics file. It can accurately reflect the color development of the actual printing. In addition, the stability of digital proofing equipment is also unmatched by other equipment. It is basically impossible to suddenly appear color inaccurate. of.
In fact, the problem appears in the image processing of the front-end design and the color reproduction of the display. These involve a complete color management solution. It is necessary to ensure the consistency of the image reflected on various devices and truly achieve "what you see and what you get" The perfect effect. Here, the adjustment of the front-end input device and display device will not be introduced. The principle is completely indistinguishable from the principle of digital proof matching printing, which is the essence of color management.
Needless to say, with the continuous development and improvement of color management technology, digital proofing will show greater advantages in the printing process and occupy a dominant position.
In production practice, the following points need to be summarized:
1. Try to keep the printing in a stable state. Enterprises should establish a set of effective printing standards, especially in terms of controlling printing density and dot gain, and require operators to resolutely implement in the printing process to control various indicators within the error range.
2. To ensure that the digital proofing equipment is in a normal state. The software is often used to detect and adjust the machine, so that the digital proofing equipment is always in a normal state to ensure consistent printing results.
3. Strictly control the printing characteristics of the test version. Whether the ICC characteristic curve of the CMYK printing source accurately reflects the characteristics of the printing equipment depends entirely on good printing control.
4. In theory, different printing conditions correspond to different ICC characteristic curves. However, for common prints and the general visual perception of the human eye, it is sufficient to set several ICC characteristic curves reflecting common printing characteristics for commonly used coated paper or matte powder paper.
4. CTP printing
The current CTP system is generally used by large and medium-sized printing companies. Most of them have several, dozens or even dozens of different types of printing machines, such as Heidelberg. Manroland, KBA, Mitsubishi, Beiren, etc., there are both single-sided printing machines and double-sided printing machines, as well as sheet-fed printing machines and rotary printing machines.
As we all know, on each lithographic printing machine, there are 125 variables that need to be controlled, so maintaining consistency in printing has become a difficult goal. In addition to the inherent and immutable characteristics of the equipment itself: on the one hand, the printing characteristics of different models of machines must be different, we cannot guarantee that different machines can print the same effect; on the other hand, even the same model Due to various factors such as the time of use and the wear and tear of the machine, the state they reflect is also different. In this way, the diversity of products will definitely conflict with the state of the printing machine, and users often encounter the situation that certain products can only be printed on one machine. Therefore, the consistency of the printing effect of the device has become the most troubled thing for CTP users today.
At the same time, if there is no perfect equipment management mechanism and good working environment, such as poor equipment maintenance environment, incorrect machine operating habits, etc., it will inevitably cause the depreciation of printing equipment, and the quality of the printed jobs produced There will be great value, and naturally it cannot adapt to the current fierce competition environment.
In order to solve these problems, first of all, we must adhere to best practices and control the work process to better manage the printing press, regularly perform maintenance and inspection of the equipment, and resolutely prevent the machine from getting sick. If there is a problem, the machine to be adjusted must be adjusted to the best condition. If necessary, the machine supplier can be asked to provide assistance.
Secondly, it is necessary to do the CTP process work in a standard state, establish printing compensation curves for different machines, and ensure the standardization and dataization of the entire set of process work in order to improve and solve the above problems.
Nowadays, the development of CTP technology is changing with each passing day. We need to analyze specific problems in the process of continuous learning and exploration, and there are no ready-made formulas and rules that can be copied. In addition, CTP technology also has many skills. Learning and applying these skills will greatly improve work efficiency.
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