title_body: Convert epub to epub, to do more heuristic processing During format conversion, Calibre can perform some heuristic processing.
  For example detecting chapters and scenebreaks.
  
  I've notices that a few epubs (especially from Project Gutenberg),
  could really do with that kind of heuristic processing.
  For example their chapters may not all be separated.
  
  Is there a way I can execute the heuristic processing part of conversion without actually doing any conversion?
upvoted_answer: Use the command-line tool
  
  [Manual]
  
  If you use the command-line tool,
  you can do just this.
  Though you need to make sure the input filename and the output filename differ.
  
  for example
  
  ebook-convert myorig.epub mybetter.epub --heuristic-processing