changing the color of material

i can make a list of all the object in a scene and i would like some help to write a little script to check the color of each faces in each object and if the color is inside a certain range then change it for a specific color

this has to be done for more than 100 object s

is there a script that already exist to do that or may be try to make a little script to do that
anybody can help for this task
this would be a nice little script for color normalisation in a scene