colour separation
noun [ U ] UK ( US color separation) uk/ˈkʌl.ə sep.ərˌeɪ.ʃən/ us/ˈkʌl.ɚ sep.əˌreɪ.ʃən/
分色（印刷）
a method used for printing, where a colour image is divided into four images of a single colour that, when put together, make the complete colour image