obtund vs unsharp

obtund

verb
  • To reduce the edge or effects of; to mitigate; to dull. 

unsharp

verb
  • To sharpen (an image) by creating a blurred ("unsharp") negative as a mask, and then combining that mask with the original. 

adj
  • out of focus; blurry. 

  • dulled or intentionally blunt. 

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