PDF function and digital workflow

The full name of the PDF is the Portable document Format. Chinese means a portable file format. According to the development of the printing and publishing industry, it is not difficult to see that the digital workflow processing strategy of the printing industry will be based on a single page technology.

It seems that Adobe's PDF file format promises to be a key technology for the future prepress digital workflow. Since the introduction of PDF, it has attracted the attention of people in the industry. However, at present, PDF has not been widely recognized by the industry. To become a true industrial standard, PDF still has a long way to go!

PDF features

When we need to display a typeset electronic file on a computer screen, PDF allows the electronic file to retain its appearance and intrinsic properties; second, we can annotate the electronic page. The third function is applied in Web technology. Although with the Internet and a large number of electronic files using HTML, but the status of PDF in the Web can not be ignored; of course, PDF is also more controversial in the current Web. People involved in the development of PDF used to think that PDF has great potential in the printing and publishing industry. They believe that PDF is a powerful tool for remote writing. In addition, PDF has a wide range of applications in the publishing industry. In any case, PDF has provided us with a choice of digital workflow options.

Comparison of PDF and Postscript

Adobe’s original intention of introducing PDF was not to replace the Postscript page description language. The definition of job information in the Postscript language is placed in a header file, and the work must include the page that the job includes. Even if you only need to handle one of the pages in your work, you have to explain the entire job information. A significant feature of PDF, on the other hand, is page independence. In a large file with multiple pages, you can treat any one of them individually. This advantage makes it possible to design a single-plane RIP (Raster Image Processor) system. This RIP system separates individual pages through many separate processors. Unlike current RIP systems, the current RIP system works by letting the entire archive pass through RIP.

The PDF format is a stable file format, and Postscript is a programming language. Many different applications can edit Postscript files. Therefore, Postscript language is characterized by dynamic variability. Sometimes this situation causes RIP to work. Disordered state. In contrast, PDF is produced in a single way, with a small file size, fast processing speed, and smoother RIP.

The Postscript page format language used to occupy a monopoly on prepress, and it was the first solution to transfer various pages on the designer's desktop to the output. However, Postscript is not a file format but a freely interpretable programming language. Although Adobe's RIP strictly adheres to the functional requirements of Postscript, Harlequin and other interpreter developers are also able to provide compatibility with Postscript, but there is still an effective way to control the output of Postscript files, Postscript may be more standard, perhaps It's accurate, but it can cause confusion in the workflow and ultimately block the main path of the prepress workflow.

The reason why people favor PDF is that the PDF format can easily transfer files, browse, play and print, and it is much more reliable than Postscript. In addition, you can edit the PDF file for a limited amount of time. In contrast, Postscript can be converted to Postscript code. Can you edit it?

The advantages of PDF format

In PDF format, you can make changes before the final output of the film, you can remove the layout of the layout of the mark and replace the previous mark with a new version of the mark. In the development of PDF, in the face of increasing pressure, Adobe has expanded the functionality of PDF and ported some color processing and printing control functions in Leve12 Postscript to PDF. We can define spot colors and color space types. Extended features include background removal, black generation, mesh addition, and overprinting. These functions are output to the appropriate image output device in a device-dependent manner. Or on the digital press.

With the introduction of Acrobat 4.0 and related PDF1.3, the function of PDF, especially the function of supporting the printing work, has been perfected. Indeed, PDF1.3 now seems to include features missing from PDF 1.2. At the Seybold Symposium in March 1998, people in the industry also cited many of the shortcomings of PDF, and others commented that PDF is not suitable for many printing jobs. The recently introduced PDF 1.3 has been greatly improved. Each PDF file carries the page's font and page content information. PDF PDF1.3 supports the color information of ICC Profile. We don't have to wait until all files are "checked in". We can process and save files. The PDF supports CMYK colors, and PDF supports some of the print job's design work, such as bleeds and printed marks. PDF1.3 now supports a variety of color systems, including black-and-white printing and three-color printing. It also has 14 built-in Typel fonts, thus preventing the use of improper fonts.

In addition, the use of a PDF work programme will relieve the printer engine of a key technical problem, and the features of PDF seem to be an understanding of the solution to this problem. The biggest stumbling block of this new technology in the transition phase of the printing industry toward computer to direct platemaking is the lack of reliable means to transfer advertising design and prepress color data information to the platesetter, and PDF is expected to play an important role in the transmission of prepress files. Character.

PDF is a problem to be solved

The current PDF technology is not perfect, and PDF files generated by different methods still have some differences. PDF files generated in Illustrator 8.0 are different from those generated in Distiller, and therefore result in the same files, resulting in different file size results. In most cases, the PDF file is small via its corresponding Postscript file, but at the same time, some basic printing elements are missing from the PDF file. PDF is best suited for soft proofing, which means that there is no guarantee that the trapping information generated in the application will not be lost. Trapping is a RIP internal process, so the trapping information generated in the QuarkXPress application software may be lost. The worse thing is that the trapping settings depend on the paper and the press. Especially in the packaging design, trapping must be considered when designing, but the trapping information in the PDF file may be lost.

There are already a number of publishing companies in the world adopting PDF digital workflows, but these companies have no intention of completely turning to PDF workflows. Because PDF was not yet a portable tool for high-resolution color files. At the same time, PDF faces the severe challenge of the TIFF-IT file format. TIFF-IT is a familiar file format for Mac users and other color systems. TIFF-IT is a partially interpreted bitmap file that is of great use in the prepress design field because it is a printing client and a locked file format that cannot be changed. TIFF-IT can help the printing company clarify the facts when the color is not copied correctly, so that the printing company can't stand up. The second advantage of TIFF-IT is that the files are easy to determine and can complete the processing of the files within a certain period of time, but the disadvantage is that it takes a long time to transfer the files.

Looking at PDF and TIFF-IT, TIFF-IT is favored by users of high-resolution color images, and PDF has a place in the field of low resolution requirements.

PDF of some application software tools

Cascade's Adxchange PDF operating tool targets news and press workflows, and the input files are filtered and pre-prepared, making the files compact, clean, and adaptable for subsequent processing.

There are also some software developers who have developed PDF-enabled applications. This is where Adobe hopes to use PDF as a standard format for print production. Applications from Adobe still lack the functionality and editorial climate. Other companies are already filling this gap quickly. Companies such as American 5D, OneVision from Europe, and EnFocus can provide many software products that produce PDF files and edit PDF files.

5D's NikNak puts PDF production on the server, so users don't have to repurchase Acrobat version software. Otherwise, in order to ensure the consistency of Distiller settings, users must purchase multiple Acrobat software.

The current leading PDF software is EnFocus Pitstop 4.0, which is compatible with Acrobat 4.0. In Pitstop 4.0, the operator can edit a PFD file, or modify the settings through macro definition settings. Pistop can actually be used as a routine check tool.

The future of PDF

The biggest stumbling block for the lack of widespread use of PDF is that QuarkXPress cannot generate PDF files. Although some Xtensions support PDF files, Quark does not yet fully support the PDF format. This is the current status quo. As Adobe developed InDesign, which uses PDF as a natural format imposition software, Quark may seriously consider this issue. After all, competition for market share has already been placed in front of Quark. As long as Quark takes this step, it will greatly promote the popularity and promotion of PDF workflows, and many printing companies will also benefit from it. In other words, there is pressure to change!

to sum up:

The 21st century has come and now that PDF can be solved, all the technical issues of the digital workflow in the printing industry are still too early. PDF has to be improved in order to become an industry standard format advocated by Adobe and its supporters. It does ensure that the file is accurately rasterized and that the file code is compact and concise. Experts believe that PDF may not yet provide a full-color management workflow, but the first step toward an automated workflow must be PDF.