leaden vs unsharp

leaden

adj
  • Dull; darkened with overcast. 

  • Pertaining to or resembling lead; grey, heavy, sluggish. 

verb
  • To make or become dull or overcast. 

unsharp

adj
  • dulled or intentionally blunt. 

  • out of focus; blurry. 

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

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