Four-color printing is the most basic printing method in brochure printing, and its requirements are very high. For professional Chinese printers or book printing companies, the mastery of printing colors is a very important basic skill, so what are the rules for color matching in printing?
One primary color or two primary colors can be used to print pure colors. The chroma depends on the number of primary color inks. The more the number, the higher the chroma.
The hue obtained by printing with two primary colors depends on the relative proportion of the two primary colors, and the hue of the printed color is biased toward the color with a large proportion.
Adding a third primary color on the basis of the pure color of the two primary colors makes the saturation of the printed color lower and the brightness correspondingly reduced, while the hue of the printed color is basically unchanged, because the mixing of the three primary colors will form achromatic colors. The effect is similar to the effect of printing with fewer colors of the same proportion and a certain amount of black ink, such as light and dark color series and dark and dark color series and three-color printing colors.
Increasing the amount of black ink on the basis of color will not change the hue of the mixed color, and will reduce the color brightness while also reducing the chroma. In color printing, this feature is often used to reduce the amount of color ink, which is called background color removal (UCR) and gray component replacement (GCR).
Generally speaking, in the technology of four-color printing, the color of the picture is the most important issue. Therefore, we must pay attention to the color problem in four-color printing.
There is a line of blue characters pressed on the yellow bottom plate, so on the yellow plate of the film, the position of the blue characters must be empty. The opposite is true for the blue version. Otherwise, the blue thing is directly printed on the yellow, the color will change, and the original blue character will become green.
There is a line of black characters pressed on a certain red plate, so on the red plate of the film, the position of the black characters should not be hollowed out. Because black can hold down any color, if the black content is hollowed out, especially some small text, a slight error in printing will lead to white edges, and the contrast between black and white is large and easy to see.
- Four-color black
This is also a more common problem. Before outputting, you must check whether the black text in the publication file, especially the small print, is only on the blackboard, and should not appear on the other three-color plates. If it does, the quality of the printed product will be discounted. When the RGB graphics are converted to CMYK graphics, the black text will definitely become four-color black. Unless otherwise specified, it must be processed before the film can be output.
- The picture is in RGB mode
When outputting pictures in RGB mode, the RIP system generally automatically converts them to CMYK mode for output. However, its color quality will be greatly reduced, and the printed product will have a light color, not bright, and the effect will be very poor. The picture is best converted to CMYK mode in photoshop. If it is a scanned manuscript, it must go through the process of color correction before the picture can be used.
Feel free to contact us to learn more about four-color printing knowledge, as a professional Chinese printer, we will do our best to serve you.