The current newspaper printing tends to attract readers and advertisers with color, and the single-sided color and double-sided color printing are widely used. How to print high-quality colors in newspapers? In addition to cracking paper, ink, and printer problems, digital processing of prepress graphics is crucial.
Newspaper printing is different from traditional commercial printing. Newspaper printing substrates are newsprint, and high-speed rotary printing presses are used. The expansion of outlets and the degree of expansion of paper are all fundamentally different from those of commercial printing. Therefore, in front-end image and typesetting of newspapers, To adjust to meet printing requirements.
1. Image adjustment color mode
In order to restore the true colors and rich levels 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 selecting CMYK mode. It is processed in RGB mode and converted to CMYK mode. When scanning with Photoshop, simply select the RGB setting option in the Color Settings option, and the color image input through the scanner is the RGB mode. Because the color gamut of the RGB mode is much larger than the color gamut of the CMYK mode, the color information can be fully expressed. Processing the image in the RGB mode will result in a wider color space and more variable processing effects.
2. Adjustment of sharpness
The printability of newsprint determines that the number of hanging lines in a color newspaper should not be too high, generally about 90 lines to 110 lines. Therefore, image sharpening is required to improve image sharpness. The degree of sharpening is related to the type and scaling factor of the original image. Usually, the sharpness of the human image is smaller, while the landscape draft may be larger; the larger the image, the greater the sharpness; the higher the magnification, the sharpening degree. The deeper it is.
3. Level adjustment
The purpose of level adjustment is to meet the printing requirements first. According to the characteristics of high rate of increase in newspaper printing outlets in the newspapers, the compensation for the increase of outlets will be compensated. The main level will be concentrated in the middle area, ie, 20% to 60% of the visually sensitive areas. The gradation of the original corresponds to the gradation that can be reproduced by the printing to make the image clear and real. Second, according to the manuscript content and level distribution, to ensure the accuracy of important parts of the tone, such as the face of the figure must be clear, adjust the value of extremely high light or dark tone, can not be a large area of ​​network.
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 crucial for obtaining a qualified printing color. The increase in the number of outlets is about 30%. The total amount of ink is 220% to 260%. With GCR, the black version is the medium adjustment, the black version starts at 30% or more, and the black version has the maximum amount of 85%.
5. Adjust the image size
In the process of group edition, do not arbitrarily enlarge or reduce the image in the version software. In doing so, you will lose a lot of image information, resulting in the printed image being imaginary or dark and adjusting. If you must change the image size, you should go back to the image processing software for editing. This maximizes the image information.
6. Small font processing
Newspaper printing speed, outlet expansion rate, there is no commercial printing so high overprint accuracy, if the use of multi-color small fonts in the layout is easy to produce fonts due to overprinting fonts fuzzy shadow ghost, the same reason should not be multi-color Use reversed white print on overprinted images.
7. Edition layout color
Tint should be dominated by bright shades.
Newsprint is uncoated and has a background color. Bright tones help give the layout a brighter feel. Color is saturated. The newsprint is rough, and the screen used for printing is thick, and saturated colors are more striking.
Now many newspapers have purchased a digital proofing system. This system generally uses the internationally accepted ICC method for color correction. The color conversion fully takes into account the color gamut of newspaper printing, and combines the characteristics of newspaper printing to ensure the color, level of detail, and light and darkness of printed color samples. The contrast is highly consistent with the final printed newspaper. After adjusting the image group edition, this detection method can be used to improve the quality of the entire newspaper's image and group edition, and in particular, the printing effect of the advertisement picture can be predicted.
Of course, plate making is also an important factor that affects the printing quality of newspapers. Now newspaper newspaper making is generally divided into two kinds of crafts. One type of photofinisher output film after sun PS version. Using this process, we must strictly control several important data. The density of the dichroic film should be more than 3.2. The fog of the substrate (including the multi-layered film stack) should be less than 0.15. The linearity error should be plus or minus 1%.
To ensure the quality of the output film, the RIP software must perform curve validation each time a new roll of film is replaced or the developer fixer is replaced to ensure that the data and output film are consistent. It is also important to regularly maintain the machine, especially the punching machine. Shaiban conditions can be added to the information bar, to enhance the stability of the printing section.
Another process is computer direct plate making. It breaks through the limitations of the traditional platemaking process through two process steps of laser photofinishing, output filming, manual imposition, and printing, and avoids flower marks, dot variation, dot inconsistency, and manual spelling caused by differences in the exposure time of printing plates in the printing process. Errors and errors caused by printing.
Color newspapers need higher overprint accuracy, faster plate making, shorter printing time, and longer newspaper news deadlines. As a result, the technology has rapidly become popular among newspapers. There are few uncertainties in this platemaking process, and data and standardization are truly realized in the platemaking process.
In the production process, we must pay attention to the output linearity of the plate-making machine, ensure the percentage of outlet dots, and correctly control the temperature and replenishment volume of the plate liquid. The direct plate making system is a digital operation plate making process composed of a digital workflow, a plate making machine, a digital proofing machine, and a fully automatic bending plate punching machine. The introduction of this process has promoted the quality standardization and data control of newspaper printing. .
In short, to ensure the quality of newspaper printing, it is necessary to grasp the quality of the original manuscript from the picture, and ensure the quality of plate making. Data processing and standardization shall be implemented from the front-end processing to the final printing.
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