countershade
/kaʊntəʊˈʃeɪd/Definitions
1. noun
A shade that is opposite in color to another shade, used in art to create contrast.
“The artist used countershade to make the dark areas of the painting stand out.”
2. noun
In photography, a counter-shade is an area of shadow that is opposite in brightness or tone to another area.
“The photographer adjusted the exposure to balance the light and dark areas, including a counter-shade in the image.”