The latest screening method to improve the quality

2022-10-03
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New addition method to improve the quality of newspaper photos

the internationally renowned industry expert lf recently introduced a new addition method that can improve the quality of newspaper photos sandyp addition technology. Sandyp is not FM plus technology, but a new am plus technology. It has been used by four newspapers in Germany, the United States, Ireland and Austria

origin

sandyp plus technology was launched by sandyscreen, a Swiss company, two years ago. Experiments show that sandyp addition technology solves most of the problems of traditional newspaper addition. As we all know, the typical problems of newspaper image reproduction are serious dot enlargement, visible rose spots and moire. In the past, these problems were often considered tolerable, but as newspaper printers are increasingly used to print other commercial prints, these problems are becoming more and more annoying. Advertisers expect their full-color newspaper advertisements to have the same image quality as their advertisements in magazines

the fundamental problem in newspaper printing is that in order to ensure the printing of newspapers at high speed, low extra stitches are often used in printing. If a finer line is used, the point will increase. If we use the method of reducing the gradient transfer curve to compensate for the increase of points, the photos will lose contrast and detail; At the same time, it also leads to the loss of dark details in darker areas. In three primary color printing, the point angle will cause inaccurate eye adjustment points to form rose spots

a further problem occurs where the points first touch each other, and discontinuous tone changes can be seen. In the normal diagonal point structure, this phenomenon usually occurs in the vicinity of 50% of the point value. This phenomenon can be weakened when using elliptic points, but it will still occur in about 40% and 60% of the places. Especially in the reproduction of human skin color, there will be discontinuous jumps, and sometimes turtle wrinkles

sandyp characteristics

sandyp solution has two characteristics in point structure: different from the oblique interrelationship of traditional points, sandyp elements are vertically and horizontally arranged; The outline of sandyp points does not have any straight edges, but presents a spiral arrangement. This arrangement and point shape means that the points start to contact each other only when the point value is more than 90%. The characteristic point structure and point shape are the source of sandyp's advantages. It is said that spiral points will not produce rose spots, which can minimize moire, increase points and spread more evenly. Through experiments, the following four points are found

① the jump of hue value only occurs in deep dark areas (the point value is more than 90%), and in these places, the jump of hue value is difficult to be noticed

② for different inks, different point angles are still used, but there is no rose spot

③ the dots do not touch in the hue range, which means that the dot increase can be more evenly distributed, and itself allows the application of a more refined number of lines. The number of extra lines of 40 lines/cm can replace 36 lines/cm, or 48 lines/cm can replace 40 lines without drinking/cm

④ using spiral points instead of square points with straight edges means that practically all moire lines in the photos can be avoided. In clothing advertisements, even photos of the finest fibers can be reproduced in newspapers

in short, it can be said that sandyp has improved the quality of newspaper photos in almost every aspect

implement

when deciding to implement the sandyp solution, the first step should be to analyze the existing preliminary statistical conditions in the prepress and printing departments. There are key standards to equip each customer with an ideal transfer curve for ink and paper. The previous research is relatively insufficient

the second step involves the realization and optimization of process parameters in rip. The point increase of the printer should be considered when setting the transfer curve. The point increase of modern rotary printing machines generally varies from 18% to 22%, and the range of changes caused by different types of printing plates is wide, which must be considered

the third step is to train prepress employees to optimize their application of image management software according to the characteristics of sandyp

the fourth step is to provide a long-term quality management program to periodically check the best replication

reprinted from: digital printing

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