I recommend you to use
this converter instead, it converts files from CBR and CBZ (i.e. image files packed into a Rar or Zip file respectively) to ePub, and not only does it a conversion, but it pre-treats them so that they're better readable. The only drawback is that folders are not supported: that is, you'll have to make one CBR or CBZ file for each chapter or volume, and said file can't contain folders within. However, once you adjust your CBR and CBZ to that requirement, the program functions like a charm. Another thing is that the screen size allows you much fun...