Now everyone is talking about digitizing hype, so what is a digital workflow? One understanding is that digital workflow is the system and technology for integrated control and management of graphic information and production control information in the prepress, printing, and postpress processes on the basis of digital information.

The need for digital workflow

1. Customers are increasingly demanding print products

Today's customers' requirements for printing production are not limited to a single product quality. Customers are continuously reducing the printing cycle in order to obtain their own interests; the requirements for printing products are getting higher and higher, and they cannot be tolerated; It has jumped out of the packaging and promotion of a single circle. There has been a reduction in the number of printed products and an increase in variety. Moreover, customers now know more or less about printing. Therefore, in the process of product printing, they also hope to be able to understand the processing status of the product in time. This will not only supervise the work of printing factories, but also enable customers to Make corresponding adjustments to the plan if necessary.

2. Printing companies are increasingly demanding on technology

The emergence of CTP technology and equipment has caused a certain impact on the traditional printing methods, but it is also the emergence of CTP that makes digital workflow possible. Nowadays, more and more companies have realized the advantages of CTP, and the application of CTP has gradually increased. With the continuous growth of CTP applications, the application of digital proofing in the process has gradually been accepted by printing companies. Therefore, the popularity of color management has become a matter of course.

Today's commercial production increasingly focuses on many aspects such as quality, efficiency and efficiency. Of course, the printing industry is no exception. In order to gain a firm foothold or even win victory in fierce market competition, enterprises must make efforts in terms of quality, efficiency, and efficiency. In order to better meet the needs of these three areas, companies need to do comprehensive and integrated control rather than local control.

The digital workflow of printing includes graphic information and production control information. For a modern printing company, to realize a truly digital workflow, it is not enough to pay attention to photo-text information replication technology, but also to control production control information. Combining the two information streams organically is the solution to the digital workflow.

The background of digital workflow in the country

Although CIP3/PPF has been in development for nearly 10 years and is currently in the CIP4/JDF stage, its response in the printing industry and related manufacturing and supply industries in China is very slow and slow. There are still quite a lot of manual operations in the printing industry in China; printing companies have a large number of equipment brands and inconsistent levels of automation, which results in many devices being incompatible with each other; the professional knowledge of the printing industry is not deep enough, and the requirements for digitization are not deeply rooted in people's minds. And so on, these have hindered the development of digital workflow in the country.

Since the digital workflow consists of a print processing system that controls graphic information and a management information system that controls the production process information, we cannot isolate the two systems in the context of today’s digital era. Social requirements. Only a digital workflow that is tightly integrated with the two systems is what the printing industry really needs today.

The composition of the digital workflow

In the digital workflow, the file format of the graphic information is PS/PDF, and the file format of the production control information is PPF/JDF. These are two completely different file formats, and the content to be expressed is also completely different, so the two cannot Replace each other. Without the PS/PDF process, the content information cannot flow in the process; without the PPF/JDF process, the prepress, printing, and postpress information cannot be fully transmitted, and the printing production departments cannot coordinate well. control. Now many large companies have launched their own process solutions, such as Kodak's Prinergy, Agfa's Apex, Screen's Huizhi, Heidelberg's Prinect, Founder's smooth flow and so on. These processes are based on the work flow of PDF and JDF, that is to say, the major process suppliers have already thought of organically combining graphic information flow and production control information flow to give full play to their respective advantages.

PDF-based graphic information flow

PDF file is the common format of the current digital process, which brings great convenience to printing production with the advantages of small file size and predictability. When we talk about digital workflows, people's first reaction is PDF-based workflows. However, PDFs convey graphic information in print production and do not reflect a complete digital workflow.

From the point of view of the process solutions of major companies, PDF-based graphics and text information processing is a series of prepress work, namely PDF generation, pre-check, imposition, RIP, proofing, output, CIP3, etc. That is, after the layout is finished in the typesetting software and a PS or PDF file is generated, the file enters the process until the final output of the print file.

At present, the process software on the market is based on various processing modules. That is, each job has a special module to process. The user can choose the module to be processed, and then only need to set all the processing parameters. The process software can follow the command. Executed, and it works well.

PDF processing: It can solve PDF generation, file normalization, and other processing such as splitting, merging, and layout modification of PDF files. In fact, the pre-check function is also implemented in this module. In the process of normalizing the PDF file, error checking, error correction, and generation of normalized PDF files can be performed as needed.
Layout: It is known that most process software does not implement the function of imposition. It is after the large-scale model is established in other compatible imposition software, it is imported into the process software, and finally the single-page PDF is embedded. Output to large version mode. However, in Founder Changliu 4.0 and NetScreen's Huizhi 3, the imposition version is handled as a module of the software itself, which can achieve the functions of ordinary books such as folding, free-to-play, and even sun-imposing.

Trapping process: Trapping is a relatively important task in prepress operations, so the trap module in each process software is also relatively important. Maybe the calculation method of trapping processing in each company's process software is different, but the effect of its processing can make the user satisfied. In general, the automatic trapping process can meet the needs of ordinary users, and some advanced trap editors are designed only for special users. After the automatic trapping process is completed, some advanced trapping edits are performed manually. After the trapping is completed, the proofing and outputting can be performed, and the previous PDF normalization process does not need to be performed again.

RIP: Rasterizes pages to generate record output data. In some printing operations, only the traditional AM network can no longer meet the high requirements of the printing quality. Therefore, the process solution must fully utilize the characteristics of various outlets so that it can simultaneously output various outlets on the same layout. . Some process software providers have also developed their own unique screening methods, such as Kodak's Staccato FM network.

Color Conversion/Color Management: Provides spot color processing, or retains spot colors or converts it to print four colors. Since the printing process includes a variety of color rendering equipment, materials, and sometimes a variety of printing processes, the process software includes color management modules. By embedding the ICC profile color profile of both devices, the process can Automatically convert colors to achieve color management.

Digital proofing: Because of the pursuit of quality, efficiency, and efficiency in digital workflows, digital proofing replaces traditional proofing to meet the requirements of printing companies. Digital proofing requires device correction, linearization, color conversion, and other processing, so it is tightly integrated with color management. Kodak's Prinergy can also provide screen proofing capabilities. Screen proofs composed of dots can enable users to clearly know the dots on the proofs and four-color separation information before digital proofing, improving accuracy. The soft proofing that other process software says is actually viewing the normalized PDF file. This can only check the content information of the proofs, and cannot check the printing outlets and color separation information.

Print output: After confirming that the digital proofs are correct, the 1-bit tiff file for printing can be output. The final output device can be a laser photosetter, a CTP, a digital printer, and the like. At the same time as the printout, PPF or JDF files should also be generated to control the operation of the equipment in production.

JDF-based production control information flow

The PDF-only work flow can only be a prepress digital workflow. Today, with the rapid development of information, the printing industry needs to be able to seamlessly link all operations from the time it is received to the entire distribution chain of the final release sales. The process system, which needs to rely on the JDF data format to achieve.

The role of JDF is to focus on the various steps in the entire digital production process, record the "input", "output" resources, and processing data at each step to control the production process, in which messages can be sent. , tracking, interruption and other interventions. To illustrate, JDF provides an "information service" that records the execution results of each step of a job in order to track the status of the job. Moreover, the information provided by JDF stipulates the structure, data format, syntax, and protocol of the information, which makes JDF a standard that facilitates the exchange of information between companies. The equipment can communicate and communicate with the production control system based on this information to achieve effective control.

JDF includes pre-press, print, post-press processing information. Although the PPF format has always included various kinds of printed information, it only conveys “how it should be done” and cannot monitor and inquire about “how to do it” and “whether or not there is a problem”. Therefore, PPF is the foundation of information exchange and interaction. It is insufficient, we need to upgrade it to the JDF format, so as to meet the intelligence and automatic control of information. JDF workflow can timely feed back error information to the production control system during the execution phase of each step; further, the equipment can respond to the query of the production control system and report the working status; more advanced, the production control system can send information to the equipment. Command, interrupt a job, re-execute or change the priority of a job. These are the places where JDF is better than PPF.

The information contained in the JDF includes: pre-press - imposition, folding, color management, RIP, plate making, etc.; printing - the amount of ink in the ink area of ​​the printing machine, the density/chrominance data of the printing control strip, cutting line and register The location of the line; Postpress - cutting, folding, collation, binding, book cover and other information.

The goal of the digital workflow is to link the entire process of prepress, printing, and postpress with digital graphic information and various production control information, so that the entire process of printing production can be handled more smoothly and efficiently, and the quality of products can be higher. To achieve this goal, the printing industry must have a deep understanding of the differences between the PDF process and the JDF process. Only by combining the two processes of PDF and JDF can we call it a comprehensive digital workflow.

In the process of applying digital workflows, users should gradually increase the efficiency, reduce operating costs, and improve product quality. They must gradually find key points that affect efficiency, cost, and quality, and deal with each module in a targeted manner to make full use of digitalization. The effectiveness of the workflow.

Errors may occur in the printing process: graphic quality, typesetting and layout, trapping, color management quality, matching of digital proofs and printing samples, and linearization of output devices. Grasp these error-prone nodes to minimize their error rate so that they meet both efficiency, cost, and quality requirements.

Development obstacles and trends

The purpose of promoting digital workflow is to integrate various control information in pre-press processing, printing, and post-press processing into computers, and to integrate the entire printing production process into a compact system using digital production control information flow. In order to eliminate the influence of many human factors, the