Detailed Prepress Operation - Separation Work Chapter 10 (Below)

5. Color separation of auto and machine type pattern manuscripts

The key to the color separation of auto and machine type manuscript manuscripts is to adopt the correct level setting method to control the overall height and height of the image, and to make the tone from the very high light lower segment into a soft tone, as shown in Figure 6.29. In the calibration, the white field is set as usual, and the black field may be selected in the area with high density or added to the ladder, and the level correction should be on the value set in the normal level to reduce the intermediate tone. The reduced value is about 10-12%. Due to the backward shift of the black field in the calibration, the reduced intermediate adjustment has been properly compensated. When color correction, various color correction functions should be used to comprehensively correct the color and ensure that each color is reproduced correctly.

6. The relationship between finished size and tone

In electronic color separation operations, many people believe that it is possible to resolve all the different color separation planes with the same level setting regardless of the image magnification. However, in the actual color separation operations, the results are very different. That is, different magnifications are used, and the method of setting the levels is also different. In short, when the same level is used to set the color separation, the larger the magnification, the shallower and flatter the divided images, and the less contrast-enriched images with high and low levels.

The main reason for this phenomenon is that when the magnification is small, the largest dot and the smallest dot can be completely discarded or removed. Conversely, when the magnification is large, the highlights and shadows of the image cannot be completely lost. This results in an overall flat visual experience on the color separation image. Therefore, there are two methods for ensuring the visual effect of an image at a high magnification. One is to use a regular color separation to deepen the level curve. The second is to move the black field density region to the high light position 1 to 2 levels (density value 0.2 to 0.40).