diff --git a/src/calibre/customize/profiles.py b/src/calibre/customize/profiles.py
index 8434773515..b57e15733d 100644
--- a/src/calibre/customize/profiles.py
+++ b/src/calibre/customize/profiles.py
@@ -244,7 +244,7 @@ class KindleDXOutput(OutputProfile):
     # Screen size is a best guess
     screen_size               = (824, 1200)
     dpi                       = 150.0
-    comic_screen_size         = (775, 1128)
+    comic_screen_size         = (741, 1080)
 
     @classmethod
     def tags_to_string(cls, tags):
diff --git a/src/calibre/ebooks/oeb/iterator.py b/src/calibre/ebooks/oeb/iterator.py
index af8dd84162..2b68b6cf57 100644
--- a/src/calibre/ebooks/oeb/iterator.py
+++ b/src/calibre/ebooks/oeb/iterator.py
@@ -135,7 +135,7 @@ class EbookIterator(object):
                 plumber.opts, plumber.input_fmt, self.log,
                 {}, self.base)
 
-        if plumber.input_fmt.lower() == 'pdf':
+        if plumber.input_fmt.lower() in ('pdf', 'rb'):
             self.pathtoopf = create_oebbook(self.log, self.pathtoopf, plumber.opts,
                     plumber.input_plugin)
         if hasattr(self.pathtoopf, 'manifest'):