What is the meaning of color in China traditional opera facial makeup?

The colors of China traditional opera masks respectively represent the following meanings:

Red: It represents loyal and heroic figures, such as Huang and Guan Yu.

Blue: It represents a strong, brave and calculating character, such as Dou Erdun.

Black: a character image representing integrity, selflessness and integrity, such as Bao Gong.

White: It represents insidious, suspicious, flying and shy people. Such as Cao Cao.

Green: stands for tenacious and irritable character. Such as: Wu Tianqi

Yellow: It represents Xiao Yong and fierce people, such as Yuwen Chengdou.

Purple: stands for honest, steady and calm people.

Gold and silver: representing all kinds of supernatural images.