Detailed Prepress Operation - Separation Operation Eight

Eight, Pisces version of the color separation operations

The two-color version separation is a method for printing two color-coded color separation images using black and white originals or color originals with different replication parameters for the purpose of pursuit of a particular artistic effect and copying, printing with one or two inks. The craft is extremely widely used in advertising, posters and posters.

1. Two-color process using two color inks

This two-color version process refers to the decomposition of the main and sub-versions from the same manuscript according to different levels of curves. The main version has a deeper level, the sub-edition level has been increased, and the contrast has increased. This is shown in Figure 6.22. When the cyan layer is set, since the four-color reproducing portion adopts two-color printing, the difference in the amount of sense is large, and if the level of the conventional color separation is used, the screen becomes thin and the amount sense is insufficient. Therefore, the tone of the midtone portion of the color separation should be about 10% deeper than that of the conventional color separation. When the main layer level is increased, that is, the ink amount of the intermediate tone is increased, the level of the dark tone portion is difficult to reproduce, in order to prevent this phenomenon. , then the sub-color separation should focus on increasing the shadow contrast, and at the same time to avoid the production of skeleton black version of the tone, the opposite effect, the color correction, the principle of two-color version of the color is more basic than the conventional color Separation, the opposite color is less than the conventional separation.

Two-color printing ink selection and color matching during printing are also very important. In the two-color printing of furniture and food, the main printing plate is usually printed with brown ink, and the sub-version is printed with inks of blue, dark green, and black. In the two-color printing of mechanical products, the blue printing master edition and the black printing subsidiary edition are commonly used. When the color separation is adopted, the hierarchical curve of lowering the main version level and increasing the sub-version level as shown in Figure 6.23 should be adopted.

2. Two-color printing process using an ink printing

The two-color printing process using an ink printing refers to printing two times using the same ink for the purpose of expanding the reproduction image reproduction density range, that is, gradation details of the image can be reproduced in the maximum possible range of highlights to darkness. .

In this process, the copied images are mostly black-and-white originals, and for the purpose of making high-grade prints such as samples, art books, and calligraphic works, the electronic highlight operations should be performed as shown in Fig. 6.24. The part level is opened (changed), the dark part should be slightly higher than the regular positive value is 90-92%, the secondary version is in the positive version 30-35% of the positive version begins to produce high light spots, using close to the contour black The level of the layout and the setting of dark spots should be higher than conventional separations.

(to be continued)

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