Digital Workflow and Printing Production Integration (II)

Second, the digitization of information

The emergence and development of electronic and computer technologies have established binary digital representations of information. The digitization of information refers to binary 0/1 digital representation information that is easily identified and processed by a computer.
The aforementioned two kinds of information flow contain a variety of information. The information has different characteristics and its digital characteristics are also different.

1. Digitization of text information

Non-digitized textual information exists in the form of "graphical symbols." People observe the appearance (image) of text characters, and make their “original appearance” into photographic paper, film and printing plates through complex processes, and then print them on paper and other materials.

The digitization of textual information consists of two aspects: encoding and font description.

(1) The encoding of text, that is, a multi-bit binary digit for each character. For the Spanish language, the use of 8-bit binary digits (1 byte) to indicate that the word symbol is sufficient (28); but for Chinese characters with a large number of characters, it requires at least 16 bits (2 bytes) to Representation (216).
(2) Digitization of text glyphs, that is, the "pattern" of text is represented by a binary number. The simplest way to achieve this is to use the text strokes and spaces as 1 and 0, respectively, to form a "matrix font." The more commonly used font digitization method is to represent the outline of the text as binary data (contour glyphs), and to restore the outline to dot matrix information when the text “appearance” (display/recording) is required.

2. Digitization of image/graphic information

For digitization of an image, the first is its electronicity, that is, the conversion of an optical image into an analog electrical signal. The process of digitizing an image is to first divide the image into pixels and then convert the corresponding signals of the pixels into binary 0/1 digital information. The image signal is converted into a digital signal through a process of sampling, quantization, and encoding.
In general, digital images represented by different-bit image signals have different color conditions. Each pixel of the black-and-white binary image is represented by 1-bit binary; black-and-white images with light-dark gradations are represented in 8-bit or 16-bit binary; whereas true-color images are mostly expressed in 3 or 4 8-bit binary representations. Rich color changes.
The description of graphic information is to graphically describe the contour of the graph with nodes, lines, and curves, and to indicate the status of its filling. Its description parameters are stored and transmitted digitally.

3. Digitization of page description information

Most of the print information is organized in the form of "pages" and "pages." Digitized page descriptions are indispensable for prepress processing.

An open, device-independent computer page description language is one of the cornerstones of digital prepress. It can describe the features and interrelationships of various graphic elements in the page. The purpose is to transfer the page information composed of graphic and textual information to the full, and ultimately "imaging" the specific device (display, printer, laser imagesetter, CTP equipment, etc.). In fact, the role of the page description language is to integrate the graphic information for the first time.

Among various page description languages, PostSript relies on its advantages to become an internationally accepted page description language. It has made outstanding contributions to the digitalization of printed information for more than a decade. However, with the advent of multimedia and Internet publishing, it also revealed its disadvantages. The PDF format is based on the PostSript imaging description model. It can integrate text, graphics, images, audio, and video information. It can form different types of publications according to different needs. It is gradually becoming the main format for digitalized page descriptions, especially in integrated formats. Digital flow related systems are widely used.

4. Digitization of production control information

Digitization of the necessary control information for printing production is based on the realization of electronic means, that is, the realization of single electronic control of printing and postpress equipment, and then the control information is expressed in binary digits to realize the “CNC” of the equipment.

Further requirements for digitally controlled printing equipment and postpress equipment are: on-line or off-line exchange of digital control information, ie, production control information can be transmitted to related equipment via the network or other storage media (disks, etc.). After the device receives this information, it also translates this information into action instructions that the device can perform in order to properly implement production.

Since there are many kinds of prepress, printing, and postpress equipment, and their features are different, the control methods and instructions are also different. Therefore, there is a need for a device-independent file format. In this format, various kinds of production-related information involved in the prepress, printing, and postpress processes are described in a language for use by various devices. The PPF and JDF established by the CIP3\CIP4 organization are the file formats that meet the above requirements. $Page break $

Third, the implementation of digital workflow

It can be seen that the digitized workflow includes two major parts of the graphics and information flow mentioned above. Graphic information flow solves the problem of "doing"; and controlling information flow solves the problems of "how to do" and "what to do." The key point is: Both types of information are digital and can be stored, processed, and transmitted by computer storage.

We illustrate the difference between the non-integrated digital work and the complete digital flow through Figure 1.
As shown in Figure 1, the customer provides graphic manuscripts, layouts, and production requirements. After the printing unit receives these non-digitized information, it performs text input/layout, image scan input/processing, and prepress processing and production of graphics. According to the customer's requirements, the digitalized multi-page information will be formed into a full-page version. Then the printing function will be used to generate the PostSript or PDF information of the layout description. After the RIP processing, the whole page color separation graphic record will be output. Go to the film or plate. When the customer agreed to formally print, batch printing began.

When performing batch printing, the operator relies on experience to adjust the amount of ink to control the ink zones of the printer; if it is desired to obtain the basic data for adjustment of the ink zone of the printer before printing, the printing plate must be scanned with a special device before printing to obtain Ink statistics for each ink control area to get the correct ink volume control on the press. After the printing is completed, the printed product is obtained through steps such as folding, cutting, and binding.

In this non-integrated digital prepress process, although the graphic information is digital, and the ink control on the printer can also be digitized to a certain extent, the production control information is still fragmented and non-integrated. The prepress, printing, and postpress processes are not very tightly linked.

The same print job's operating status under the integrated digital flow is shown in Figure 2.
The client provides the original manuscript, layout, and production requirements. After receiving this task, the printing unit determines the appropriate copying route, distribution printing and post-press processing equipment according to the basic characteristics of the printed product and the customer's requirements.

The prepress processing stage was conducted in the same way as described above. After the imposition of the imposition, the information relating to hand-sheet folding, cutting, binding, and registration rules has been determined. After RIP processing, the record information for each plate was obtained. This information can be used for two purposes: First, it is used for film or plate recording, and secondly, this data can be used to count the ink control basic data of each ink area of ​​the printing machine. Thus obtaining the ink amount control data information eliminates the step of printing plate scanning.

After the printing plate is produced, during the printer adjustment stage before the printing is officially started, the multi-color overprint adjustment can be performed by using the registration position data already generated in the pre-printing stage; at the same time, the ink amount adjustment data that has been obtained can be used to print the printing machine. The ink volume of each ink zone is adjusted without having to repeat the test printing, so that the printing press can quickly enter the formal printing state, which saves material and shortens the time spent.
After the printing is completed, prior to the post-press processing such as cutting, folding, affixing, etc., the information such as folding, cutting, etc. already generated in the pre-printing stage can be recalled, and presetting of the folding machine, cutting machine, and binding machine can be performed. , To make various equipment quickly into working condition, carry out post-press processing and production, and finally get printed products.
From the above comparison, it can be seen that in the integrated digital workflow, various equipment control and pre-adjustment status information required for printing and printing have been obtained in the prepress stage. As long as the information is accurate and can be smoothly transmitted to printing and postpress equipment, these devices can quickly enter the normal working state of a product. This saves the overall adjustment time, reduces and avoids the operation of things, is conducive to improving the quality of printed products. It is these digital control information that link prepress, printing and postpress to form a complete production chain.