grayscale vs monochrome

grayscale

adj
  • Black and white, representing color with shades of gray. 

verb
  • To convert to grayscale. 

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

  • The use of black and white, representing color with shades of gray. 

monochrome

adj
  • Representing colours with shades of gray. 

  • Having only one colour. 

noun
  • A ceramic glaze of a single colour; an object so glazed. 

  • A black and white image, especially such a photograph. 

How often have the words grayscale and monochrome occurred in a corpus of books? (source: Google Ngram Viewer )