Change to color : White

I have a test video:

http://cassandra-rune.com/medias/test_lumiere.mp4

On after the 2017 effect, I try to change the color of the object in white. I want to replace the white by a gray or black color, like a shadow.

Or the special effect "Change Color" does not work on white.

Do you have an idea, a tips, or a plugin?

Thank you

Antoine