shade in

shade in

v.
1. To represent degrees of shade or shadow in some drawing or picture, so as to give the illusion of depth: The artist shaded in the contours of the model's face in the portrait.
2. To darken some bounded area that is drawn or printed on a surface: The teacher shaded in the area where the circles overlapped with yellow chalk. I'm going to shade in the left side of this drawing with crosshatches to make it darker.
See also: shade