Monochrome: printing with only one color ink; For example, we usually use black ink to print on white paper, which is monochrome printing. Of course, ink is not necessarily black, but red, yellow, green and so on; Paper is not necessarily white, but can be colored paper of various colors. As long as it is printed with one ink, it belongs to monochrome printing.

Two-color: As the name implies, it is printed with two colors of ink. (The conversion between paper and color is similar to monochrome)

Four colors: three primary colors (yellow, magenta and cyan) and black for printing. In four-color printing, four films are printed on each page, which can be stacked together to print color patterns. These four films are cyan, magenta, yellow and black. But don't think that the film marked "cyan" is cyan and the film marked "magenta" is magenta. These four kinds of films only use different gray levels to indicate the depth of a certain color when printing.

If you make pictures on the computer, it is best to choose CMYK value as the mode, because four-color printing is generally used for printing, so don't use RGB value, otherwise the printed effect will have color difference! !

I hope it helps you!