etching vs gravure

etching

noun
  • The art of producing an image from a metal plate into which an image or text has been etched with acid. 

  • The image created by this process. 

gravure

noun
  • A type of intaglio printing process, in which an image is engraved onto a rotating copper cylinder. 

  • A style of Japanese softcore; glamour photography. 

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