Dot Shape Analysis (3)

6. Special shape outlets. From a technical point of view, changing and selecting different dot shapes is a need for printability. However, in order to meet the needs of art reproduction, advertising, and special interest, special shapes of outlets (or art reticles) are often used to increase the artistic atmosphere of the picture and obtain specific artistic effects. The commonly used art reticulates are concentric circles, horizontal wavy lines, vertical lines, crossed cross-woven gauze, gauze mesh and brick wall textures.

Different dot shapes have different effects on dot gain during printing. Through experiments, the conclusion is that the best dot shape should be a regular chain-like structure with circular dots in the highlight and dark tone, and elliptical dots in the middle tone.

The following figures are the effects of diamond screening, linear screening, and cross screening, respectively. (In order to observe the convenience of using 30 lines / inch production (all using Photoshop production), the actual printing effect is much better), we can easily find three images in the figure to express the different effects.

Through the introduction of different outlets above, we learned that when selecting outlets for different products, we must also consider the performance of the outlets for different products. For example, the level of square outlets is much stronger than that of chain outlets. In the selection of special shapes of dots, do not blindly choose. The first question that should be considered is what shapes of dots are more effective in expressing the theme of the printed material, and whether this choice is really necessary. For example, the chain-shaped dots themselves are characterized by softness in the middle tone, and then chain dots can be used in many intermediate-tone (especially characters) prints; water-wave dots have the unique dynamic of water waves, often It will be used in special situations such as water sports; similar performances include concentric circles for vortices, brick-shaped dots for buildings, broken-line dots for speeding cars, and single-line dots for bamboo.

The above mentioned choice of different shapes of dots has a very broad meaning for the production of lithographic printing.

The same is true for dot shape selection. It is not as rich in gravure printing (especially engraving and gravure printing). Due to the limitation of the engraving process (which is mainly limited by the engraving knife), the dot shape used in gravure printing is often very simple. Rectangles and diamonds. However, for gravure printing, the change in the shape of dots has had a new effect.

Unlike the peace version, the dot shapes of the various color groups on the gravure printing plate (plate cylinder) are often not the same. The general situation is that the yellow version and the black version use almost square dots, the cyan ones use longitudinally-stretched diamond dots, and the magenta ones use horizontally-stretched diamond dots (the above are relative to the respective screen angles). With this change of dot shape, gravure can be more effective to avoid the occurrence of moire fringes on the printed material due to the lack of dot dot angle (only three kinds of dot angles for engraving gravure: 45, 30, 60).

Similarly, unlike plain printing, gravure printing seldom considers dot gain in the printing process, but rather considers the problem of ink transfer rate (ink rate in the cell). During the test, people find that the The amount of ink transferred in the printing process is similar to that of a dot that is close to a circle. Based on this, in the development of gravure printing, hexagonal line dots and octagonal dot dots have continuously appeared (because of the limitation of the engraving knife). It is almost impossible to produce a circular dot on a gravure plate cylinder.

In the above article, some descriptions of the features and functions of the different shapes of the outlets were made, and it is hoped that they will help the readers in the future work.


Author: Xu Lina surgery Source: net win