duotone
/ˈduəˌtoʊn/
noun
- A picture or design that uses two colors or two shades of the same color.
- The artist created a striking duotone of the city skyline using black and gold.
- For the vintage poster, they chose a duotone with deep blue and pale yellow.
- The photographer printed the portrait as a duotone to give it a classic, moody feel.