Four-color printing, printing with subtractive primary colors (yellow, magenta, cyan) and black. If the yellow, magenta, cyan, and black inks are used for the printing process of copying the color of the original, other than four-color inks, they should not be called "four-color printing" but should be called "spot color printing" or "spot color. print".
A full-color reproduction lithography method using the principle of subtractive mixing with red, green and blue primary colors and black colorants (inks or dyes).
It also specifically refers to the use of black, medium blue, brown, green four inks, to achieve map copy lithography method, it is China's large-scale topographic map often used printing methods, and a unified color standard. The color of each element shall be defined as: ground features, figure outlines, and annotations shall be black; waterside lines, single-line rivers and their annotations shall be blue, and the dyeing part of the water department shall be 100 lines/inch 15% medium blue dot. Contour lines and special geomorphological symbols and their annotations, brown color for general road interiors, and 100 lines/inch green screens or outlets for forests.