Current newspaper printing trends use color to attract readers and advertisers, and single-sided color and double-sided color printing are widely used. How to print high-quality colors on newspapers? In addition to solving the problems of paper, ink and printing presses, the digital processing of pre-press graphics is very important.
Newspaper printing is different from traditional commercial printing. Newspaper printing substrates are newsprint, and high-speed wheel transfer newspaper machines are used. The expansion of the network and the expansion of paper are fundamentally different from commercial printing. To adjust to meet the printing requirements.
1. Color mode for image adjustment
In order to restore the true color and rich layers of the image as much as possible, the image color must be adjusted in the RGB color mode. When using Photoshop to process images, the effect of selecting RGB mode is stronger than the effect of selecting CMYK mode. Processed in RGB mode, and then converted to CMYK mode. When scanning with Photoshop, just select the RGB setting option in the color setting options, and the color image input through the scanner is the RGB mode. Because the color gamut of the RGB mode is much larger than that of the CMYK mode, the color information can be fully reflected, and processing the image in the RGB mode will result in a wider color space and more variable processing effects.
2. Adjustment of sharpness
The printing suitability of newsprint determines that the number of net lines for pictures in color newspapers should not be too high, generally around 90 to 110 lines, so sharpening is required to improve image clarity when adjusting images. The degree of sharpening is related to the type of the original image and the zoom ratio. Generally, the sharpness of the person image is smaller, but the landscape draft can be larger; the larger the image, the greater the sharpness; the higher the magnification, the sharpness The deeper it is.
3. Level adjustment
The purpose of the level adjustment is to meet the printing requirements first, according to the characteristics of the newspaper printing dot increase rate, compensate for the increase of dots, and concentrate the main level in the middle area, that is, 20% to 60% of the visually sensitive area The tone of the original corresponds to the tone that can be reproduced to the maximum extent to make the image clear and true. Secondly, according to the content of the manuscript and the distribution of levels, ensure the gradation of important parts is accurate. For example, the faces of people, etc. must have clear levels, adjust the value of extremely high light or very dark tones, and do not block large areas.
4. Mode conversion
The image mode used for printing must be CMYK mode. Pay attention to the color separation setting options in the image processing software. Setting this parameter correctly is very important for obtaining qualified printing colors. The dot increase is about 30%, the total ink volume is 220% to 260%, using GCR, the black version is a middle adjustment, the black version starts at more than 30%, and the maximum limit of the black version is 85%.
5. Resize the image
In the process of group version, do not enlarge or reduce the image in the group version software at will. Doing so will lose a lot of image information, causing the printed image to be false or dark tones. If you must change the image size, you should go back to the image processing software for editing. This will keep the image information to the maximum.
6. Small font processing
Newspaper printing speed is fast, the dot expansion rate is large, and the overprint accuracy is not as high as commercial printing. If you use a multi-color small font in the layout design, the font is easy to produce. The font is blurred and ghosting due to inaccurate overprint. Use small highlights on overprinted images.
7. Group plate layout
The color tone should be based on bright tones.
Newsprint is uncoated, has a base color, and bright tones help to give the layout a bright feel. The color should be saturated. Newsprint is rough, the mesh used for printing is coarse, and the saturated tones are more eye-catching.
Now many newspapers have purchased a digital proofing system. This system generally uses the internationally accepted ICC method for color calibration. The color gamut of newspaper printing is fully considered in the color conversion. Combined with the characteristics of newspaper printing, the color, level of detail and brightness of printed color samples are guaranteed Contrast etc. are highly consistent with the final printed newspaper. After adjusting the image group version, this detection method can be used to improve the quality of the entire newspaper image and group version, especially to predict the printing effect of the advertising picture.
Of course, plate making is also an important factor affecting the printing quality of newspapers. Now the newspaper making is generally divided into two processes. One is the PS version after the film is output from the imagesetter. Using this process, we must strictly control several important data. The solid density value of the dichroic film should be above 3.2, and the haze of the film base (including the multi-layer film superimposed) should be less than 0.15. The linearity error should be plus or minus 1%.
To ensure the quality of the output film, every time a new roll of film is replaced or the developer fixer is replaced, the RIP software must perform a curve effect to ensure that the data and the output film are consistent. Regular maintenance of the machine, especially the film machine, is also very important. If you have conditions for printing, you can add an information bar to strengthen the stability of the printing process.
Another process is computer-to-plate. It breaks through the limitation of the traditional plate-making process through laser phototypesetting film and manual imposition and printing, which avoids the flower marks, dot variation, dot inconsistency and manual spelling caused by the difference in the exposure time of the printing plate during the printing , Errors and errors caused by printing.
The color newspaper needs higher precision of overprint, fast plate-making speed, shorten printing time, and extend newspaper news deadline. Therefore, this technology is rapidly popularized in various newspapers. There are few undeterminable factors in this plate-making process, and the digitalization and standardization are truly realized in the plate-making process.
In the production process, we should pay attention to the output linearity of the plate-making machine, ensure the output dot percentage, and correctly control the temperature and supplement of the processing liquid. The direct plate-making system is a fully digital operation plate-making process consisting of digital workflow, direct plate-making machine, digital proofing, and automatic bending plate punching machine. The introduction of this process has played a role in promoting the quality standardization and data control of newspaper printing. .
In short, to ensure the printing quality of newspapers, we must start with the quality of the picture manuscript, ensure the quality of plate making, and realize the dataization and standardization from the front-end processing to the final printing.
Weihai Tong Park Arts & Crafts Co.,Ltd , https://www.whtongpark.com