1.3.3 Electronic prepress

Costly and material, time, labor consuming photoengraving was completely replaced by the electronic reproduction in electro-mechanical engravers and scanners after the fifties of last century. Tone value of an each original copy element have got in such devices (Figure 1.7) the supplementary intermediate, not inherent in previous photo stage, presentation in form of analogue and later on digital electric signal. Its value is directly defined by some optical parameter, for example, the reflectance factor of an element captured on original as well as of a simultaneously recorded one on the color separated transparency.

Figure 1.7. Analogue color scanner Chromograph DC 300 ER of Hell completed by the unit (on the background) with a six digit storage of one stroke signal for image scaling and digital halftoning (1972 ).

It has formally complicated the workflow as far as the following steps were supposing the certain return to image materialized presentation on a substrate of a transparency, plate, color proof or print. Moreover, the first scanners imperfection forced to once again use of a camera for image screening and sizing.

In spite of all that, the facility of flexible image parameters and, first of all, its color control by such a signal manipulation happened to be determining and urgently demanded. It had greatly saved the efforts of etchers, photographers, retouchers, as well as the expense of time and consumables along with uprising the most of print quality parameters.

Some scanners, such as of PDI Time-Life Inc., provided simultaneous output of four CMYK transparencies by the use of four recording heads. The premises of prepress conjunction with the other media using electric channels had also appeared.

1.3.3.1 Remote publication and reproduction

There was earlier used to deliver the printing plates (stereotypes) of daily newspapers to per ferial locations by the railway or plane to safe the news actuality.

As of 60ies of the last century the apparatuses for newspaper pages facsimile transmission were developed to remotely record the photo plates [1.2]. That has significantly increased the speed of newspapers output in spite of the need of repeating plate making at a local print house. Central newspapers were printed in all, for example, USSR regions with the use of facsimile equipment designed according to in-dram recorder concept being later on widely accepted in prepress imagesetters design.

The facilities of electronic reproduction were in possible way used at different stages of development also for the other technical and page design purposes looking ordinary on the background of modern computer aided prepress. It was, for example, related to the remote reproduction where a certain part of technology steps is performed at one location, for example, of publisher or correspondent, the other – in prepress shop or design studio and the final one – in print house.

One of such attempts was undertaken in the synchronous operation of two electronic Hell electronic engravers Vario Klishograph at the Olympic Games of 1966. Color slide taken in Tokyo was scanned by the image capturing section of such machine. Its signal was transmitted by telephone line to control the heads engraving cliché in similar machine in Osaka.

Later on, at Olympic Games of 1978, the CMYK halftone transparences were remotely, by satellite communication channel, output at Time in New York from slides taken in Los Angeles with the similar use of digital Magnascans of Crosfield.

Special photo facsimile equipment was for the same purposes developed with its transmitter implementing the functions of a color scanner while its receiver - a CMYK imagesetter [1.3; 1.4].

There were also the other kinds of supplementary functions used in extent of electronic reproduction equipment developments. They were in particular related to pasting up the pictures on a page or to creating the simplest decorative elements. For such a purpose the analogue Combi Chromograph scanner had, for example, an additional scan unit generating the auxiliary “masking” signal to be combined with that of reproduced image to withdraw the background, produce frames, etc. Later on the each further step in microelectronics developments was tried to be usefully exploited in prepress technology applications.

Such supplementary functions were significantly expanded when it became possible to digitize and to store in a buffer memory of about ten kilobytes the image signal of at least one scan line. With digital control of scanning and recording heads in axial position it allowed for varying location of an exposed area in circumference direction. Scanner operator had input the control data according to the scheme of color separated transparencies placement on single sheet of recorded film as is shown in figure 1.8.

Figure 1.8. Recordation of CMYK color separations set on the same film sheet in scanner 1970ties owing to the facility of intermediate storage of one stroke image signal in a buffer memory.

For lack of computer page layout in 70ies, such means allowed for the significant accelerating of preparation of such a high volume illustrative editions as, for example, the sales booklet with ten color pictures of different items on each of its 500 pages and, hence, with the five thousand slides to be processed. The control system MultRun of Hell has saved from manual mounting the transparencies on a final photo plate by recording each of ten images precisely in target location on the same sheet of exposed film. Such positioning was provided by the program controlling the scan head search of desired slide among multiple fixed on a transparent input drum of a scanner as well as the start of a scan line signal output from the buffer memory to precisely place a recorded image on a film in circumferential direction.