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.