Principle of four-color printing machine

Screen printing is the most commonly used printing technique nowadays, especially the four-night overprinting. If you open an image in CMYK mode, you will see four separate channels, which represent the cyan, magenta, yellow and black colors used in printing. These channels can be used to create four different films, which can then be stacked together to produce the final print. The idea is to create separate films based on the way the colors are distributed in the original image.

To create the silk screen plate, a process called sun exposure is typically followed. The plate is used to print one color at a time, with each layer allowed to dry before the next one is added. Sometimes, multiple colors are stacked together to create a new color such as orange, which can be achieved by printing red and yellow in overlapping layers.

While it is possible to use only the three primary colors of red, yellow and blue, it's not very practical because mixing them together tends to dull the colors. Therefore, an additional color layer is added on top of these three. In PS, all four colors are mixed together to achieve the desired shade, but during printing, only black and blue are used to print black.

It's also important to keep in mind that printing cannot produce very bright colors, so the color range in RGB mode is much broader than in CMYK mode. While selecting colors in PS, you may notice a warning triangle next to some colors. This means that those colors cannot be printed properly, and you'll need to adjust them accordingly.

in printing.