What is written on the head of Black Impermanence and White Impermanence?

On the head of White Impermanence, the official hat reads, "At the first sight of wealth": it means to thank and give good luck to those who respect the gods.

Black Impermanence's hat reads "Peace in the world": this means that there is no amnesty for those who disobey the law and commit crimes.

White Impermanence's name is Xie Bian, which is Yang.

The name of the Black Impermanence is Fan Wuxiu (or Wuxian or Wu Gui), which is Yin.

Extended Information:

Black and White Impermanence are the most famous ghosts in traditional Chinese culture.

The names Black and White Impermanence are not due to differences in skin color or clothing color. Black and White Impermanence is just a representation of yin and yang attributes, "black" and "white" represent one yin and one yang, that is to say, Black Impermanence represents the yin body and White Impermanence represents the yang body. This is also consistent with the contrasting colors of the yin and yang fish in the Tai Chi diagram (black for yin and white for yang).

The theory of "impermanence" is also inseparable from the Taiji diagram, and the theoretical basis of "impermanence" is the doctrine of yin and yang.

Reference:

Baidu Encyclopedia - Black and White Impermanence