lettering vs rotogravure

lettering

noun
  • Written text, especially when printed. 

rotogravure

noun
  • A portion of a printed work produced by this method. 

  • A printing process by which the paper is rolled through intaglio cylinders. 

  • A print made by such a method. 

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