1.3 Stages of prepress development

1.3.1 Evolution of plate making

Several generations of pre-press technologies have replaced the former ones during last decades introducing novel imaging techniques and equipment. Each time that required, in its turn, the serious replacement of production means and training content in relation to operating skills, image processing, color management, etc. Important, instead of completely putting aside, to substitute the previous stage related knowledge by detailed analysis of essentially negative features of former technique which forced to move to its next generation. Not out of place either to mark some useful features inherent in previous stage but not available at the beginning of the next one. Some examples of such analysis and accents are given below.

In Middle Ages the prepress comprised a page print forme making with both letters and pictures engraved by a single person. Following the invention of typesetting such job was for over three centuries divided into two parallel text and image processing routines each of them using the essentially different qualifications, tools and, during its latest period, rather sophisticated electronic equipment. About three decades ago, as schematically shown in figure 1.3, it once again converged into an entity due to the computer desktop facilities used by the single operator.

Reasons of these processes initial separation and their recent convergence are in the principal difference of two kinds of input graphic data. Even if relatively conditional, the image comprises, the most part, the replica of visually perceived world. Text is, to the contrary, the initially ciphered data with its letters or hieroglyphs comprising the graphic codes of sounds or ideas. Such distinction of the processed matter has required, in turn, the different artistic skills of engraver and composer. Nowadays, it becomes possible to bring such distinctive data to the unified form of an eight digits combination appreciated by Mac or PC. In a text file, one of the 256 meanings of a byte can indicate a target font, while in an image file it points out a pixel tone value (halftone dot area, ink coverage).

Figure 1.3 From manual plate engraving of middle ages to digital layout of today.

Layout systems have appeared shortly after such unified presentation became available for the volume of digital data for a whole page. First of all they were required in gravure printing to replace manual pasting up the original for magazine pages and, as well, to delete cumbersome scan unit (shown at the left in figure 1.4) providing the control signals for cylinder engraving heads. The first color system of that kind - Helio Data Processing – HDP (Figure 1.5) was created in the late 70s by Dr. Ing. R. Hell firm [1.1].

Figure 1.4. Without computer aided layout it was used to scan the manually pasted up magazine pages to get the signals for control the cylinder engraving heads.

Figure 1.5. Electronic engraving of gravure cylinder in the first computer layout system Helio Data Processing of Hell (1978).

The latest radical changes of prepress picture processing methods and means have put the printing industry beside the other so called “high technologies”. A certain academic problem of an “old” and “new” knowledge relationship has periodically aroused with the progressive implementation and partial or sometimes complete mutual displacement of engraving, photochemistry, electronics, laser, computer and networking techniques. In this respect the following stages of data processing for printing can be distinguished after the times of manual engraving to reveal the dialectic of technology evolution:

• photomechanical processes starting from 1880ies;

• electronic reproduction

analogue signals as of 1950;

digital signals as of 1970;

• computer processing systems

closed (CEPS) as of 1980;

open (PostScript based) as of 1990.

Each time, over more than the last hundred years, these changes had a serious effect on the training content. At coming to each following stage it was required to “trim” the “old” knowledge with providing the optimal conformity of the rest of it with the “new” one within the course credits limits. In this respect, it is valuable the retrospective analysis of the basic reasons for move to a novel technology along with disclosing the usually inherent in trade off as far as at each of such transitions the cost and quality indices had shifted the ascents in social and economic infrastructure of the industry. Discussion of the basic features and principle changes is useful for adequate evaluation of the current state of technology and for revealing the trend of its development. So, it’s not out of place to give some examples of such issues for the above listed stages.

With their comparatively short history the electronic means of media (radio, TV, internet…) were created on the “precise knowledge” basis in times of technical revolution. Printing, as an integral part of mass media, does, to the contrary, exist over a centuries. Some of techniques formerly found due to individual skills, intuition, craftsmen experience and being still used or already canceled hadn’t got the adequate explanation of therein involved physical, chemical and information processes in the light of modern science.

Effective implementation of electronic, television and computer techniques was also restrained by the traditions inherent in printing. Replacing of camera based photomechanical reproduction by the electronic one goes back, for example, just to 60ies of the last century, i.e. to the time when the TV pictures were received from space for the other side of Moon.