1.3.4 Computer aided prepress
Functional transforms of an image signal were performed in former electronic reproduction in real time. Each picture element was recorded on a film or plate simultaneous to the moment of a corresponding pixel capturing from original. There was no facility to modify this signal selectively for the given image area or for the so called sophisticated retouching. Text and pictures have to be manually layout on a page. Originals for electronic engraving cylinders of gravure printing were prepared by already mentioned (Figure 1. 4) pasting up pieces of text and image color separations both prepared electronically, and even digitally, in typesetters and scanners.
Principally new facilities have appeared in prepress technology when it became possible to present in computer memory the information for a whole page. They were first of all comprised of electronically combining two principally different kinds of graphic data – text and illustration. Local, sophisticated retouching with the use of all means of computer graphics became also available. One of the first such technology implementations relates to the already mentioned Helio Data Processing (HDP) system of Hell (Figure 1.5).
Color Electronic Prepress Systems (CEPS) development has started yet by the end of 70ies. That’s why they have had to use the original, specific file formats, hard and software designed by their vendors and are characterized as the “closed” ones, i.e. having no facility for the graphic data exchange and communication within the print/publishing environment.
Following personal computer and networks appearance has caused the disruptive move in mass media, social life and, as well, in printing technology. Separate prepress operations had started to be in this or other volume performed by remote from each other participants with use of the standard page description language Postscript and later of PDF file format. Beside of the print house itself one could meet among them authors, publishers, advertizing agencies, design and repro studios... Due to its operational and socioeconomic advantages the “open” systems concept occurred to be so urgently demanded that, may be for the first time in prepress history, the great number of rather new CEPS with their costly input – output units became not any more needed.
However, similar to other mentioned above technology stage transitions there weren’t some principle shortcomings avoided. The remarkable quality deterioration of multicolor printing had place with coming to open systems as beginning of 90ies. Its basic reason was comprised of diverse color meaning interpretation by different image inputs and software applications in open prepress environment as schematically demonstrated in figure 1.12.
Figure 1.12 Various means of image capturing and its intermediate presentation differently interpret the color of an object thus creating the problem of the input signals non conformity.
These inputs use to generate unequal three RGB bytes for the same source color as if speaking different languages. Various kinds of output are as well requiring not equal control signal values to create the same target color on a print or a monitor screen (Figure 1.13).
Figure 1.14. Different kinds of output require non equal control signals to provide the same color.
That’s why the Color Management Systems (CMS) were rather urgently developed to solve this problem. Instead of previous predominantly used color densitometry they lean up on colorimetric measurements for color values conform in specification developed by the International Color Consortium (ICC) and received thereafter the status of ISO standard.
Direct, avoiding transparencies preparation, the print plates making, which was widely used over fifty years ago, was once again renewed in Computer-to-Plate (CtP) systems. According to the Direct Imaging (DI) concept some of such systems operate inside a press with automatic plate installation.
Appearance of digital printers, comparable by productivity to certain class of traditional ones, looks like completing the “electronic/digital” revolution in printing industry. Dialectically such printers take there the conceptually new role of a network peripheral unit rather than of a traditional press.
In a broader retrospective the evolution of illustration printing is presented by G.G. Field in his book “The color printing revolution” [1.13]
It isn’t out of place to remark at the end of this chapter that the transition to each further step of development has had essentially changed the structure and content of graphic technology education. Analysis of an “old” and “new” knowledge relationship in this area was given in [1.14].
Summary issues
Modern reproduction can be presented as comprised of two parallel chains with one of them used for the layout and processing the picture content while the other - for control these data workflow.
Stages of manual engraving, camera, electronic and of computer aided image processing have been replacing each other within the copy preparation technology developments. Camera process had to use manual and costly color retouching and page layout making to transfer to electronic and later on to computerized reproduction.
Even the small steps in TV, electronics and digital techniques development were tried to be explored for advancing the prepress technology.
Graphic data presentation in form of analogue and then encoded electric signals allowed for the greater flexible control of an image parameters as well as for the prepress conjugating with the outer media systems.
Unified presentation of principally different text and image data by the digital binary code is cornerstone for the current stage of prepress technology. Along with radical improvements the transition to next step was inherent in certain shortcomings and compromises to be further withdrawn.
Tests
The greatest share of the print product cost is related to expenditures on:
а) ink;
b) payment to author/designer;
c) printed substrate;
d) plate making and printing;
e) distribution.
1.2 Dividing the plate making onto parallel image reproduction and text processing routines was fundamentally caused by the:
а) appearance of manual typesetting;
b) photography invention;
c) image and text data diversity;
d) press invention.
1.3 Recent convergence of these routines has taken place due to the:
а) applying of “digital phototypesetting”;
b) unified encoding of a font and picture element;
c) facility of a computerized layout;
d) raster and vector computer graphics exploring.
1.4 Manual engraving replacement by the use of camera to process the continuous tone original became possible because of the:
а) photography invention;
b) photographic glass plate replacement by film;
c) projection screen use;
d) development of a reproduction photo camera.
1.5 Principal shortcomings of that replacement were in the:
а) tone rendition deterioration;
b) increase of consumables consumption;
c) time consuming;
d) fine detail distortion;
e) lack of manual retouch facility.
1.6 Basic reason of camera reproduction replacement by the electronic one was comprised in the:
а) need to conjugate prepress with the electric communication channels;
b) reduce of material and labor consumption;
c) unifying parameters of materials and equipment;
d) improving of print quality parameters.
1.7 Principle distinction of electronic reproduction from foregoing camera use is in the:
а) facility of sophisticated retouching;
b) image presentation by electric signal;
c) cheaper equipment to be used;
d) digital encoding of color values.
1.8 The most principal shortcoming of transition to electronic reproduction is related to:
а) equipment sophistication;
b) image sizing difficulties;
c) discrete structure of an image presentation;
d) halftone kind of an image generating;
e) increase of materials consumption.
1.9 Basic function of the softproof is in visualizing the result of:
а) original image capturing;
b) printing;
c) layout;
d) image corrections;
e) plate imposition.
1.10 Changing the size of a screened transparency mostly effects on:
а) its copying properties;
b) halftone frequency;
c) tonal content of an image.
1.11Basic advantage of transition from electronic to computer aided reproduction is in:
а) processing speed increase;
b) image signal digital presentation;
c) facility of text and pictorial data layout;
d) facility of the image output on a monitor.
1.12 Reproduction in the real time of scanning doesn’t facilite the:
а) spectral selective color correction;
b) layout and local retouch;
c) image sizing;
d) halftoning;
e) look-up table based color correction.
1.13 Main disadvantage of CEPS was the lack of facility to:
а) send a prepress data by electric channel;
b) exchange said data with others;
c) local retouching;
d) text and pictorial data layout.
1.14 Transition from the “closed” to “open” computerized prepress had committing the:
а) color data diverse interpretation;
b) lower speed of processing;
c) worse retouch quality;
d) greater cost of software;
e) complicated layout.