Secondaries with the Pros - The Art and Technique of Digital Color Correction - page 240

Fig. 6.55 Field just talked through this secondary correction during the session. I reconstructed it later
using his instructions.
Fig. 6.56 Recreated secondary data.
“Then use a secondary to pick the narrowest range of the floor,
so it isn't affecting anything else and desaturate it and maybe swing
towards red a little bit to blend in with the shadows more. With the
secondary, look at the matte to see what part of the picture you're
affecting.”