Bleeding (actually "preliminary cutting") refers to the convenient cutting part reserved for retaining the effective content of the picture when printing. Color bleeding is a common printing term. Bleeding in printing refers to increasing the pattern of the external size of the product, and adding some pattern extensions at the cutting position, which are specially used in each production process within its process tolerance range to avoid white edges or cut content in the cut finished product. When we do it, it is divided into design size and finished product size. The design size is always larger than the finished product size, and the big edges should be cut off after printing. This part to be printed and cut off is called bleeding or bleeding.