photoengraving vs rotogravure

photoengraving

noun
  • A process of transferring a photographic image onto a plate which is then etched and printed. 

  • A plate or reproduction made using this process. 

rotogravure

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

  • A print made by such a method. 

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

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