Four-color printing is the most basic printing method in brochure printing, and its requirements are very high. For professional printers or businesses, understanding four-color printing is a very important basic skill. What are the rules for color matching in printing?
The color can be printed with one or two primary colors. The degree of color depends on the size of the primary ink. The higher the quantity, the higher the concentration, such as the light solid color series and the solid color series, and the 28 to 30 page double color series. colour.
The color of the two primary colors is printed depending on the relative proportions of the two primary colors, while the color of the printed color is biased towards a larger proportion, as shown by the colored rings on pages 10 and 13:
Adding a third primary color based on two main color printing monochromes can make the printing color density lower, the brightness is lower, and the printing color tone is basically unchanged, because the three primary colors are mixed to form an achromatic color, and the effect and the reduction are similar. The color ratio adds a certain amount of black ink prints, such as the light and dark series and the three color printed colors.
Increasing the amount of black ink on the basis of color does not change the color tone of the color mixture, reducing the color brightness and reducing the purity, such as the 31-33 two-color series and the 44-70 tri-color series and the four-color color; the color of the three-color primary colors is close to In the case of proportional printing, a low-purity color similar to I-color is produced, which is similar to black and has a certain color printing. In color printing, this feature is often used to reduce the amount of color ink, called background color removal (UCR) and gray component replacement (GCR).
In four-color printing, the color of the image is the most important issue in four-color printing technology, so we must pay attention to the color problem in four-color printing.
Hollow
There is a blue word in the yellow plate. In the yellow version of the film, the blue position must be empty. The same is true for the blue version. Otherwise, the blue thing will be printed directly on the yellow plate, the color will change, and the blue word will turn green.
2. Field overprinting
A red line is pressed on the red plate, and the black word is not hollowed out in the red film. For black, you can suppress any color. If the black content is hollow, especially for some small text, a slight error will result in white display, while black and white contrast is large and easy to see.
3. Four-color black
This is also a common problem. Before outputting, you must check the black text in the published document, especially the small words, not only on the blackboard, but also in the other three colors. If it does, the quality of the finished product will be greatly reduced, the RGB graphics will be converted to CMYK graphics, and the black text will definitely become a four-color black. Unless otherwise specified, it must be processed to output the film
4. The image is in RGB mode
When the RGB mode is output, the RIP system automatically converts it to a CMYK mode output. However, its color quality will be greatly reduced, the finished product is light in color, not bright, and the effect is very poor. In photoshop, images are best converted to CMYK mode. If it is scanned, it must be color corrected to be used.