Newspaper Printing Requires Editing Design and Prepress Technology

To improve the printing quality of color newspapers, and to better play its role in propaganda, education, entertainment, etc., the main issues to be solved are to improve the clarity of the images, the range of tone levels, the color saturation, and the evenness of the ink. Based on newspaper editorial design and pre-press plate making theory, this article combines color newspaper publishing and printing practices to talk about prepress process control for color newspaper production.

1 Edit design

There are certain limitations in the overlay printing accuracy, color brightness, gradation tone, and evenness of ink color in the printing of color newspapers. Editors and designers should make corresponding designs on the basis of understanding these technical characteristics, avoiding their technical limitations and maximizing To play its advantages.

1) The editor should choose images with strong contrast, high definition and rich levels when choosing images, and create a good condition for color separation and plate making.

2) Special care should be taken when editing electronic artwork. The resolution of the pictures on the Internet is often low, and the resolution of the pictures in the HangPipe plate-making system is 200dpi to 300dpi. Therefore, pictures downloaded from the Internet must have high accuracy; other electronic manuscripts should also pay attention to accuracy requirements.

3) Due to the characteristics of newsprint, it is determined that the highlights of the highlight area are easily lost. The dark tone adjustment points are easy to expand, and the level of brightness is also lower. Editors should use high-purity color or the color of high and middle tone areas as the dominant color in designing colors, and should expect that the set colors have the problem of bottom ash and color shift of newsprint during printing.

4) Since the overprinting accuracy of the rotary machine is limited, in the design of color characters or anti-white characters, the use of Song type and small-size characters should be avoided, and the superposition of small characters should not exceed two colors.

5) The uniformity of the ink layer printed on the newsprint on the newsprint is limited by the conditions. The flat screen with a large area should be reduced as much as possible, especially the multi-color overprinted screen is extremely difficult to print evenly.

6) The press of the rotary press is positioned by the pressure of the pressure roller, and it is easy to press the dirty part in the middle seam. In the choreography of newspapers, it should try to avoid arranging thick text and images in the newspaper.

2 Prepress production

The newsprint printing and printing equipment used in the printing of newspapers, etc. determine that the printing of color newspapers is different from ordinary color printing. It is necessary to stabilize and improve the printing quality of color newspapers. Prepress production process control is very important.

1) Image processing

1 scan settings

In order to adapt to the printing process characteristics of color newspapers, the setting of the scanning should focus on improving the clarity and gradation of the picture. The following aspects should be noted.

Set the scan resolution properly. In general, the input resolution is between 200dpi and 300dpi, which should not be too high.

In order to reduce the level of loss, the range of gradation should be set to the maximum range during scanning, and black and white fields and tone curves are pre-set according to the type of picture.

为 In order to improve the sharpness, sharpen the image, that is, adjust the sharpening value appropriately according to the specific situation of the image.

De-web processing of printed manuscripts.

Black and white field settings. Black and white fields are the starting point and the end point of the image tone. Correctly setting the black and white fields is the key to grasping the tone. Since the whiteness and ink density of newsprint are much lower than those of general color prints, the tone of printed newspapers is compressed to a smaller extent. In order to improve the printing effect of the image, the black and white fields must be appropriately set according to the characteristics of the image subject, and the tone that does not affect the subject image area is intentionally compressed so as to play a role in increasing the contrast.

For general color prints, in order to achieve color reproduction, the level of the high-profile area is preserved, and the white field is usually set to a high-light area where the range is relatively small. In the printing of newsprint, the small outlets in the high light area are easy to lose, and the paper itself has more than 5% of gray scale. Too much emphasis on the level of bright tuning will affect the overall tone range, making the picture dark. Therefore, the Whitefield area should be appropriately expanded, and sometimes it is necessary to sacrifice some bright-toned levels in order to highlight the main body. At the same time, it should also be noted that the area of ​​the Whitefield should not be too large to prevent a large area from being blocked.

Whether the picture level is rich or not is reflected in the dark tone. For general color prints, the darkest, smaller area is mostly selected as a black field in image processing. However, according to newsprint printing, the high expansion rate of outlets and the ease with which the outlets appear to be hierarchical, in order to take care of the overall effect of the image, it is also necessary to abandon some of the darker levels when necessary.

Level 2 correction

The correction of the level curve is to compensate for the gradation that is compressed by setting the black and white fields, to expand the dark tone, and to avoid the dark divisions, and to increase the contrast and adjust the ratio of high, medium, and low tone to ensure the main level. Correctly restore and increase the three-dimensional image. The correction of the image level should be analyzed and handled according to the type of the tone. It requires the operator not only to have experience, but also to have the ability to understand and process the image.

Color correction. Some images have color casts, which can sometimes cause changes in the hue of the image during black and white field setting and level compensation. In order to improve the color reproduction of the image and adapt it to the printing conditions of the newsprint, color correction must also be performed.

The color correction is done according to the gray balance processing, but also according to the characteristics of the newsprint itself with grayscale and color shift, the purity of the printing color is reduced, and the color purity is appropriately processed.

For a picture with a certain color as the basic color, the basic color may be appropriately exaggerated and given enough, and the amount of the opposite color may be appropriately reduced. For example, the red color is reduced by blue, the green color is reduced by (red), and the blue color is reduced by yellow to strengthen the color. purity.

3 printing ink settings

Total ink control. Due to the limitations of newsprint printing, this parameter cannot be too large. Otherwise, there will be a serious pile-up phenomenon. After the print test, it is recommended that the parameter be set to 240%, that is, the sum of the four inks should not exceed 240%.

GCR (ash component replacement) and UCR (background color removal). The GCR is the color of the gray area where the three inks of cyan, magenta, and yellow are synthesized, and the neutral gray of this part is replaced with the black ink; the UCR is the gray part of the dark tone synthesized by the three primary inks and the black ink is used. instead. Both of these methods are to reduce the total amount of ink during printing to reduce the pile-up phenomenon. Because UCR is sometimes difficult to control on the press, GCR is generally used. After the print test, it is recommended that this parameter be set to Medium, that is, the portion with a tone lower than 20% is not replaced with black.

Black ink control. This parameter controls the maximum amount of black ink after color separation. After printing tests, it is recommended that the black ink volume be controlled below 85%.

Ink color settings. This parameter records the characteristics of the ink used for printing. The setting that applies to newspaper printing is SWOP, the web offset specification (newspaper).

Dot expansion settings. This parameter records the dot gain in printing. The setting of this value will affect
The images in Photoshop are displayed so that they look similar to the printing effect. In addition, the dot enlargement of the four inks used in printing may be inconsistent. Therefore, dot gain values ​​for cyan, magenta, yellow, and black inks may be separately set.

2) Picture output

At present, most newspaper printing companies in China still follow the traditional process of splitting and printing with the separation film as the master. The quality of the separation film affects the printing quality and affects the print quality of the newspaper.
Output software RIP settings. RIP, full name raster image processor, hardware RIP and software RIP, is currently used software RIP. The role of RIP in a color desktop publishing system is very important. It relates to the quality and speed of output, and even to the operating environment of the entire system. It can be said to be the core of a color desktop publishing system. The main role of RIP is to interpret various images, graphics, and text in the layout of a computer into dot matrix information that can be recorded by a printer or an imagesetter, and then control the output device to record the image dot matrix information on the output media.