Although some domestic printing enterprises have introduced digital proofing and CTP and other related equipment to realize local digital production, through the superficial phenomenon of digital printing production, it is found that the utilization rate of CTP equipment in many printing enterprises is not high, which is caused by their own comprehensive management and improper selection of CTP system.
A complete CTP system not only includes digital proofing, CTP and other output devices, but also includes digital workflow. Digital workflow is the core of CTP system, which controls all output devices. Therefore, to evaluate the quality of a CTP system, we should not only examine the performance of each output device, but also consider the overall process efficiency generated by the matching of digital workflow with each output device. Therefore, when choosing CTP system, we can consider the following aspects.
1, CTP process flow is seamlessly connected with the original phototypesetting system.
At present, the use of imagesetter in printing enterprises is relatively large, and it is not allowed to give up the process based on imagesetter immediately in actual production. Therefore, CTP equipment and imagesetter will coexist for some time. The complete compatibility of CTP system with the original imagesetter system means that it can be compatible with imagesetters of different brands, and all equipment can continue to play a role in the CTP process.
2. The core technology conforms to international standards.
PDF file has become the technical core of digital workflow because of its good stability, strong compression performance and portability of different platforms. At present, its implementation standard is PDF 1.5. In actual production, the file types from customers may be varied, such as PDF, PS, DCS, TIFF, JPEG, 1 TIFF, etc. The CTP process must be able to convert various types of documents into PDF international standards.
3. Really realize "one rip, multiple outputs"
1 bit TlFF, also known as electronic film, is a rasterized file, which has become an international standard after RIP. The multi-output of electronic film is really "one RIP, multiple outputs". To judge whether the workflow conforms to this definition, we only need to see whether the file waiting for rasterization in the process is a single-page file or a large-scale file. If it is a large version of the document, it does not belong to this definition.
4. Meet CIP4 requirements and support JDF standards.
The most striking feature of CIP4 is that it defines the production status of printing jobs. Supporting JDF is the most basic requirement of CTP process, and it is also the premise of digital workflow and printing resource management system to transmit information.
5. Ensure the stable transmission of color.
Color management has always been a concern of printing enterprises. The color management links in workflow, such as digital proofing and related color lossless conversion process, provide a guarantee for the improvement of workflow efficiency.
The high-tech CTP technology with wisdom as the core has the advantages of strong flexibility and good elasticity, which can be seamlessly combined with the existing phototypesetting system of any printing enterprise and can fully meet the requirements. It can be described as a tailor-made CTP process. It can not only be used in conjunction with CTP, but also fully adapt to JDF and PDF 1.5. It can easily convert PDF or PS workflow into JDF-based environment, and realize smooth information transfer with prepress, printing and post-press operations. At the same time, it can be connected with advanced printing resource management system (ERP) to provide more timely and effective data guarantee for enterprises. Its excellent color management software BlackMagic and its workflow after RIP make efficient production full of fun.
In short, the high-tech commercial CTP process not only provides the core of color management, but also integrates the unique ColorGenius color conversion engine of Huizhi, which ensures the consistency of color transmission in CTP process and allows you to experience tailor-made surprises.
In the digital prepress workflow, the film no longer exists. Image files are saved as digital information until they are output for printing. This form of digital workflow is becoming more and more popular. This paper will introduce the outstanding characteristics of digital workflow and all aspects related to CTP workflow.
In the past few years, the development trend of printing industry has been developing towards completely digital workflow. With the breakthrough development of DTP system and CTP technology, the digital workflow from designing printed manuscript to completing final printed matter has become a reality. The digital transformation of printing industry has brought more and more intense pain, which is inevitable when any innovative technology is put into application. This transformation means that the design and completion of digital workflow will face a series of challenges.
Because the concept of complete digital workflow is relatively new, it is impossible to establish its industry standard at present, and all that can be determined at present is only the links that make digital workflow work successfully. In the design of printing workflow, the order of these links can be changed to meet the special requirements of some companies. In order to help us understand this digital transformation, we will introduce the advantages of CTP, common terms, important links in successful digital workflow and some factors that need to be considered in digital workflow design.
Advantages of digital workflow
CTP technology has obvious advantages, such as the improvement of image quality, because the image is obtained by first-hand digital data, avoiding the quality loss caused by intermediate conversion. Imaging directly on the printing plate reduces the problem of color registration that is easy to occur in multi-color printing, improves the quality of tone reproduction and better controls dot gain.
Its second advantage is to save money by completely canceling it. In addition, the disposal and waste of contaminated materials are greatly reduced. Due to the reduction of labor cost and conversion procedures, it will inevitably bring less waste and improve printing income. But also eliminates the printing film processing equipment and saves the production space. In a word, digital workflow is more convenient than traditional methods in image finishing.
But any technology has its limitations, and CTP system is no exception. At present, the main obstacle of CTP technology application is the investment cost of CTP system equipment and consumables. Secondly, the digital workflow should be carefully designed to make the printing process fast and accurate. At the same time, digital proofing method is also necessary for a perfect CTP system. Although on the surface, CTP system has nothing to do with employee training, in fact, whether CTP system can be widely popularized is closely related to operator training, because training skilled workers in digital data processing also requires high investment cost.
CTP digital workflow
So far, the industry standard of CTP system digital workflow has not been officially promulgated. In workflow design, the main problem is how customers and printers negotiate with each other to confirm the equipment they agree on and the type of printing work they will engage in. Although there is no uniform standard, any CTP workflow design needs some clear links and steps, so that the formulated workflow can meet the guidance of specific printing work.
These steps are mainly:
(1) customer file input
(2) Image preparation (if necessary)
(3) Preview
(4) imposition and color matching
(5) page language conversion and output
(6) plate making and quality control
(7) printing
Figure 1 shows a typical digital workflow design. Next, we will introduce each step of digital workflow and the matters needing attention in design in detail.
Figure 1 Typical Digital Workflow Design
Information exchange between printers and customers is the main factor for the success of digital chemical process design. Customers need to know what file formats printers can accept and the capabilities of printing enterprises. All input files should be standardized in a well-arranged format for plate-making equipment to identify and use, and can be transmitted in the media format required by the printer (such as software, network transmission or LAN transmission). When the file is loaded into the workflow, the software in the system should make it objectively displayed. At this time, you can sample the document in the printing factory (send the sample back to the customer for approval), or you can send it back to the customer electronically for proofing (use traditional proofing or soft proofing).
● Preview
Once the printer receives the document, the first step is to pre-check the document, that is, check whether the document is correct when it is sent to RIP for imaging output, check the required characters and images in the document, and check and identify the damaged parts of the document and any other possible problems.
Although it is still a controversial issue in the printing industry whether to pre-check documents in the workflow, many printers have pre-checked documents in the prepress part. Ideally, the customer service representative should preview the printed document when it arrives at the printer and provide feedback to the customer quickly. At present, there is a special software for pre-inspection (not confirmation) of documents, so customers can also complete the pre-inspection of documents themselves, saving the possible expenses incurred by printers in providing services.
Even so, the importance of document preview should not be exaggerated, that is to say, designers should not rely on document preview to find all errors, but should correct them from the beginning to ensure that they pass the whole process smoothly. The purpose of proofing and document pre-inspection in workflow is to find problems as soon as possible, and to confirm problems as soon as possible when making documents, not after plate making is completed. Only in this way can it be considered economic.
● Digital proofing
In CTP workflow, the reliability of digital proofing is considered to be the weakest. CTP technology can adopt several types of proofing methods: color proofing, imposition proofing (also known as blue line proofing) and comprehensive proofing of the two. Because CTP technology does not use film, it is impossible to adopt film proofing methods (such as Matchprint or Chromalins), so it is an inevitable choice to adopt digital proofing methods. Use high-end inkjet, dye diffusion and laser color printers instead of traditional proofing equipment.
Due to the characteristics of different printing methods, digital proofing methods have been difficult to achieve the effect of frequent proofing. One of the main reasons is that digital proofing method adopts continuous tone processing technology, which can not produce semi-continuous tone dot structure proofs. Digital proofing proofs are gradually accepted by customers and printers, and become the quality commitment or final proofs to customers. However, if halftone dot proofing is not used, it will be difficult to detect the potential moire fringe fault in screen printing, so printing operators must learn to use tone matching method to check the printing quality in the printing process, instead of using the traditional dot structure matching method. If non-traditional screening methods are adopted, such as frequency modulation screening method, it is very beneficial to adopt continuous modulation proofing method. One way to solve the above problems is to use digital proofing machine, which can simulate semi-continuous screening proofing, but the cost is high. Therefore, printers often have various types of proofing equipment to meet the special requirements of production (for example, large-format inkjet printers are used for imposition proofing and Kodak is approved for color confirmation proofing).
Another reason that restricts the application of digital proofing technology is the difference between proofing color and printing ink color. Therefore, it is necessary to apply color management methods to compensate the differences caused by different pigments. Whether a CTP system can succeed in the end is very important for deciding what kind of film-free proofing method to adopt to obtain samples acceptable to customers.
●PS processing
After the file pre-inspection step is completed, PS software (page description language) is usually needed for processing. The application of PS can make different marking equipment of various manufacturers play a role in the printing process. Therefore, the document gets a print label, which contains all kinds of production information, so as to process and identify the printed works reasonably. After that, producers and prepress operators can start to work and apply various software (such as color registration, imposition or color management software) to deal with this printing. Then, the processed printing job is sent to the plate maker/printer or stored in the database for storage.
Digital image files are very beneficial to repeated calls, which refer to images that are stored in digital form again when needed. Therefore, various printing activities can be conveniently stored in data files and called in the form of CD or through the network when necessary.
● Image raster processor RIP
The print data output device needs translators to understand the PS grid or the described print file. Print files are transmitted to digital output devices through RIP. RIP performs three tasks on files: language conversion, item list and image rasterization. RIP converts PS format file language, which is to convert the file into a language that can be read by marking equipment. The project list is not a document list, but a separate description of each project (text, illustrations, pictures, etc.). ) Number each page in the form of a list. The rasterization of the document is actually an operation guide, which tells the marking equipment when and where to mark the polar axis, what shape point to use, and other similar information. Once the file in PS format is sent to RIP, it is generally considered that the file has been confirmed, and the printed file (including errors) will be output in PS format.
There are two types of RIP: hardware RIP and software RIP. Hardware RIP is composed of computers and software provided by suppliers. When RIP software is upgraded, the supplier provides upgrade service. The disadvantage of this RIP is that the processing capacity and storage capacity of computers in the system are limited by hardware. Software RIP is the software that runs RIP. You also need to buy a computer. The advantage of this RIP is that you are no longer limited to a specific computer, and you can buy the faster and more powerful computer you need. General RIP usually has many vendors who can provide various types of RIP in any system configuration.
In CTP workflow design, another point worthy of attention is whether image processing adopts single RIP or multi-RIP output. It is best to use the same RIP output for plate making and proofing to avoid the difference caused by different RIP image outputs. But unfortunately, according to this work, when RIP is used for proofing, it is impossible to make plate. Therefore, whether to use a single RIP or multiple RIPs depends on the printer and the way they like to work.
● Imposition proofing
Also known as blue line proofing. This kind of proofing is mainly to check the final position of each part of the printed work in the layout and verify whether the positions of cutting marks, folding marks, registration marks and color marks are correct. This kind of proofing should be the last proofing before plate making, and its proofing size is the same as the printing size. For some customers, the color quality of imposition proofing can also be considered as the final color proofing.
● Plate making
In the process of plate making, it is very important to remember that the plate making process of printing plate is completely different from that of film. Since the printing operator has obtained the customer's approved sample, any mistakes in the document must be corrected before plate making. Once the plate-making is completed, it is necessary to carry out quality inspection, including smooth plate-making process, correct RIP output, exposure and resolution test, diagonal direction, minimum/maximum dot change and so on. Because no plate-making method is perfect, once the printing plate is installed on the machine and printing begins, it will cost a lot to repair the undetected errors. A well-designed digital workflow can avoid invalidation or any mistakes in redoing printing.
conclusion
The breakthrough technology of CTP/DTP system shows that a complete digital workflow has the potential for success. Improving image quality, better controlling dot gain, reducing registration problems and reducing quality loss caused by intermediate steps are only part of CTP's advantages. The main advantage of CTP system is to cancel the film, thus avoiding many problems in the production of color separation film and reducing the cost. CTP system is an ideal prepress solution, but the transition to digitalization has brought pain to any innovative technology application. Even if the upfront investment cost is put aside, how to balance investment and income, the most important factor is a perfect digital workflow. Understanding and mastering the key steps in digital workflow (communication, pre-inspection, proofing and imposition) will ensure the successful application of CTP system in any printing plant.