Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1995-10-23
1998-06-30
Coles, Sr., Edward L.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
395102, 395109, 395114, 358500, 358518, 358523, 382112, 382239, H04N 146, G03F 308, G03F 1500
Patent
active
057746354
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a procedure for controlling printing quality, as specified in the preamble to claim 1.
BACKGROUND OF THE INVENTION
It is conventional practice in printing technology to measure the darkness of the printing on a printed specimen, and the alignment with each other of different colours, and to use the results of measurement towards such adjustment of the printing machine that printed products of good quality will be achieved.
In currently applied quality measuring methods, test marks are printed in different colours on the side of the printing proper, their location or their darkness being measured in order to determine the quality. Such test marks are usually printed outside the actual printing area, and outside the area of the printed product, in the marginal area of the paper web or sheet, which is trimmed off later. The problem encountered in the use of such measuring marks is that they cannot always be positioned in marginal areas which are to be trimmed off later, and they are instead placed among the printing proper. This is usually the case e.g. in newspaper printing. In that case, however, the measuring marks will be visible in addition to the printing, whereby they impair the printing quality. Another problem is the extra work at the prepress stage caused by the use of separate measuring marks.
The quality-related problem just outlined can be reduced by using measuring and density marks smaller than before and by combining these, as has been described e.g. in the Patent FI-78025. It is to be noted, however, that even these measuring marks will be visible if they are placed among the printing proper.
SUMMARY OF THE INVENTION
The object of the invention is to eliminate the problems just mentioned. The object of the invention is, specifically, to provide a simple and advantageous printing quality measuring method which can be employed towards versatile quality monitoring in conjunction with any kind of printing machine, independent of the product which is being printed.
DESCRIPTION OF THE INVENTION
The procedure of the invention for controlling printing quality is characterized by that which has been stated in the claims following below.
The invention relates to a procedure for controlling printing quality in which the digital presentation of the page original is utilized. The digital presentation of the page original is obtained, for instance, from an electronic page-making system or by making an image of the page original, film or printing plate and digitizing the image.
The starting point of the printing control method of the invention is that prior to the printing process a number of measuring points are determined from the digital presentation of the page original, on the basis of given initial data. The initial data contain one or several definitions. With the aid of these definitions, one finds a point of measurement e.g. in a predefined area of the page to be printed presenting e.g. the desired level of darkness (e.g. screen pattern percentage). Furthermore, the desired sizes of the measuring points are given in the initial data. The measuring points are, most advantageously, rectangular areas. One may furthermore in the initial data set the desired number of measuring points and the allowable tolerances of the measuring points. On the basis of these initial data, suitable measuring points are sought in the digital presentation of the page original.
Two at least of the measuring points are locating points on the basis of which all other measuring points can be located on the printed page or in any corresponding area. Such locating points are characterized by having in different component colours such details which do not occur in the immediate adjacency of these points, and said details consisting, to greatest advantage, of sharpest possible darkness variations with heavy contrast (borders or equivalent) with a view to facilitating location both vertically and horizontally. The rest of the initial data are set in accordance with the kind of measurements o
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Kuusisto Matti
Launonen Raimo
Soderg.ANG.rd Caj
Coles Sr. Edward L.
Insinooritoimisto Data Oy
Wallerson Mark
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