The structure of the heaven and earth cover
The heaven and earth cover box is divided into an upper cover and a lower cover. The upper cover is the earth and the earth is commonly known as the earth and earth cover. There are two kinds of...
What is four-color printing
What is the order of the four-color printing color sequence? The four-color printing process is based on the subtractive color mixing law, using the three primary colors of yellow, magenta, and cyan...