image vs knock off

image

verb
  • To create an image of. 

  • To create a complete backup copy of a file system or other entity. 

  • To represent by an image or symbol; to portray. 

  • To reflect, mirror. 

noun
  • A statue or idol. 

  • What a function maps to. 

  • A file that contains all information needed to produce a live working copy. (See disk image and image copy.) 

  • A form of interference: a weaker "copy" of a strong signal that occurs at a different frequency. 

  • The subset of a codomain comprising those elements that are images of something. 

  • A mental picture of something not real or not present. 

  • A characteristic of a person, group or company etc., style, manner of dress, how one is or wishes to be perceived by others. 

  • An optical or other representation of a real object; a graphic; a picture. 

knock off

verb
  • To make a copy of, as of a design. 

  • To rob. 

  • To defeat. 

  • To halt one's work or other activity. 

  • To have sex with. 

  • To remove, as a discount or estimate. 

  • To assign (an item) to a bidder at an auction, indicated by knocking on the counter. 

  • To remove by hitting (something, someone) 

  • To kill. 

  • To accomplish hastily. 

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