PS determines a value in the picture. How to correct the hue and color of the whole picture?

The drawings given by the landlord have mixed colors, so you can't directly use brushes instead of tools. The following methods can be accurate to pixels.

First, create a color range and select ALT+S; C tolerance is 16%, then select expand twice, and then review the selection. If there is any surplus, use other selection tools to narrow the selection, and finally set the cmyc color data directly, and draw the selection directly with a brush. This is the simplest, roughest and most accurate color replacement method.