With vision difficulties, my grandpa can't read text whenever backgrounded  by dark color in the PDF in the screenshot beneath. Please download it from 
http://www.mediafire.com/file/1iil649lu ... 9.pdf/file, or see some of its pages at 
https://books.google.com/books?id=WM8oC ... &q&f=false.  It's too unproductive to remove each use of the dark background color one-by-one. Thus how can I, in one brisk stroke?
 
 I've Adobe Acrobat DC Pro, Foxit PhantomPDF, and Nitro Pro. They and SensusAccess converted the PDF to a Word file's that's too deformed. Acrobat states  no background to be removed.
