grayscale

/G R EY1 S K EY0 L/
noun
  1. 1

    A printed strip of graduated tones used to check exposure and development times.

verb
  1. 1

    To convert to grayscale.

adjective
  1. 1

    (imaging) Black and white, representing color with shades of gray.

Source: https://en.wiktionary.org/wiki/grayscale