title_body: how to NOT have calibre reduce pictures' resolution when converting from epub (or anything I guess) to MOBI
upvoted_answer: If you go to:
  
  Preferences->Preferences->Common Options->Page Setup
  
  you can set the Output Profile to Tablet. The Profile description reads:
  
  
    Intended for generic tablet devices, does no resizing of images [Screen size: unlimited]