Comprehensive Understanding of Digital Proofing (I)

Proofing is used as a link between prepress and printing. It is not only checking the quality of the work of plate-making and proofreaders. And provide the basis for the printing process and standards, but also an important means of quality management in the production process. As a post-process of plate making. It is the reproduction process of image synthesis. It is the inspection 2 of the plate making effect as a pre-printing process. It is a trial production of analog printing, seeking the best conditions for formal printing and providing ink standards.

A qualified proof can be used for analog output with a color separation film in the traditional way, and can also be output on a digital proofing device. That is to say; proofing can be divided into two kinds of analog proofing and digital proofing output. The fundamental difference between these two proofing methods is whether there is a traditional film output. With the development of pre-press digitalization and network technology, the digital process flow of pre-press “Yuan film” has begun to enter the pre-press field as a living force, and the proofing technology is undergoing a new digital revolution.

First, the characteristics of digital proofing

The so-called digital proofing is a new type of proofing technology that directly outputs electronic manuscripts after digital processing. It adopts a digital method to directly output the proof with a large-scale printer, which is used to replace the lengthy technological processes such as film in simulation proofing and printing.

In the wave of digital rushing to face. The printing industry has high hopes for digital proofing. Industry experts believe that rapid and stable have become the two major advantages of digital proofing. Mainly reflected in: First, good reducibility, color stability. As the artificial proofing is mainly used for manual ink pressure and adjustment pressure; so the effect can not remain stable, no digital proofing is the use of all-digital process flow, thus avoiding the uncertainty of the human factor in the traditional proofing. Second; proofing speed; save time. Suitable for short-run printing. Print a high-quality facing sample proof and digital proofing is completed within 20 minutes. Analog proofing takes 30-40 minutes. Thirdly, there are few intermediate links and the use of film is eliminated. On the one hand, it reduces the printing and printing processes in the traditional proofing process. On the other hand, it also caters to the development trend of green printing and is conducive to environmental protection. Fourth, since all the entire process flow is digitalized, it is easy to use and easy to operate. Fifth, remote digital proofing can be achieved. Due to the use and development of network technology, digital files are delivered to remote sites, and proofing equipment is used for digital proofing so as to provide users with digital proofs. This remote digital proofing breaks the limitations of time and space. Simple and practical.

Of course, digital proofing is in full time to show its elegant style; its shortcomings have also been revealed. Its shortcomings are mainly reflected in: First, although the development of digital proofing technology is becoming more and more mature. However, the digital proofing process is not yet very mature; in particular, digital proofing equipment lacks uniform standards; it is difficult for operators and customers to adapt. Secondly, because some digital proofing uses FM outlets, the operating technology of this outlet is more complicated than before. This is difficult for industry insiders who are used to AM sites to adapt. Third, the application scope of digital proofing is not universal, and it cannot meet the requirements for special color proofing such as hot stamping and hot stamping. Traditional proofing can easily be resolved at this point. Fourth, consumables problems are more prominent. Because digital proofing requires the use of special paper, the first is the increase in printing costs, and the second is the impact on the credibility of proofs. Fifth, the matching of management software for digital proofing with matching equipment such as printers, photo-setters, etc. is still not compatible with the situation. Therefore, as far as the current status of digital proofing is concerned, the general popularity of digital proofing is slow, and the original cost of consumables, etc., requires a traditional analog proof if the requirements for the live source cycle are not tight.

Looking at the development of the printing industry, from the perspective of foreign countries, the advanced countries have started to popularize and popularize digital proofing. Some developing countries have only just begun to use; from the domestic situation, digital proofing technology has been widely used in gravure printing, but The development of offset printing is still in its infancy. At present, the popularization of digital proofing technology in Guangzhou, Shenzhen and other places is at the leading level in China.

In today's digital proofing and analog sampling coexistence, although the characteristics of digital proofing has become clear, there are still some areas that need improvement in development and application. Therefore, comprehensive promotion still needs a process. From the point of view of technological development, digital proofing technology eliminates the interference of human factors and other external factors, greatly improves the reliability and stability of proofing output, and shortens the technological process as much as possible. With digital proofing, samples can be modified at any time. Theoretically, taxes can reduce costs. With the popularization and promotion of digital proofing technology, it can completely solve many problems in the long proof production period, unstable proof quality, and high cost of analog proofing, thus triggering another digital revolution in the printing field. It can be foreseen that digital proofing is a general trend to replace analog proofing.

Second, digital proofing technology

Digital proofing technology is becoming an integral part of the digital printing pipeline. Digital proofing technology is mainly divided into four types: digital semi-continuous dot network technology; continuous tone inkjet technology; dye sublimation technology (Dye-Sublimation) and revamped inkjet technology (dro-On-Demand referred to as DODL). In addition, other digital proofing technologies such as variable point transfer laser technology and hot wax technology have also been applied in digital proofing systems. However, the specific application is not extensive. The following briefly describes four common digital proofing techniques.

1. Digital semi-continuous modulation technology

This technique is based on the action of a thermal laser, using CMYK four dyes to form images on sub-sheets and then superimposing each sub-sheet to form a proofing sample. This technique simulates dot gain patterns and dot angles in printing as well as other printing characteristics; inks are provided for WOP colors (sometimes GRACol and Eurocolor) by using special sub-sheets.

The use of laser imaging digital half-tone dot proofers can not only compete with similar proofs in quality, but also surpass it. However, because the color values ​​such as hue, saturation, and aperture degree on the sub-sheet are relatively fixed, it is difficult to transmit the color point using the equipment of the car continuous adjustment technology, which is a fatal disadvantage of the application of the technology. Manufacturers using this technology are currently working hard to develop a sub-laminate production line for ordinary mercury color, but the use of the effect is not satisfactory. And Kodak Company is looking for a breakthrough in the other direction. The "color spectrum" created by the company's Approval can be copied and output by using the CMYK on-screen color episodic points.

(to be continued)