# Add cover support, if any.
         if cls.uses_cover:
             if options.image_cache:
-                transform_args['cover'] = lambda x: WLCover(x, image_cache = options.image_cache)
+                def cover_class(*args, **kwargs):
+                    return WLCover(image_cache=options.image_cache, *args, **kwargs)
+                transform_args['cover'] = cover_class
             elif not cls.cover_optional or options.with_cover:
                 transform_args['cover'] = WLCover
 
 
 #
 import re
 import Image, ImageFont, ImageDraw, ImageFilter
-from librarian import get_resource
+from StringIO import StringIO
+from librarian import get_resource, OutputFile
 
 
 class TextBox(object):
         'PNG': 'image/png',
         }
 
-    def __init__(self, book_info):
+    def __init__(self, book_info, format=None):
         self.author = ", ".join(auth.readable() for auth in book_info.authors)
         self.title = book_info.title
+        if format is not None:
+            self.format = format
 
     def pretty_author(self):
         """Allows for decorating author's name."""
     def save(self, *args, **kwargs):
         return self.image().save(format=self.format, *args, **kwargs)
 
+    def output_file(self, *args, **kwargs):
+        imgstr = StringIO()
+        self.save(imgstr, *args, **kwargs)
+        return OutputFile.from_string(imgstr.getvalue())
+
 
 class WLCover(Cover):
     """Default Wolne Lektury cover generator."""
         u'Współczesność': '#06393d',
     }
 
-    def __init__(self, book_info, image_cache=None):
-        super(WLCover, self).__init__(book_info)
+    def __init__(self, book_info, format=None, image_cache=None):
+        super(WLCover, self).__init__(book_info, format=format)
         self.kind = book_info.kind
         self.epoch = book_info.epoch
         if book_info.cover_url:
 
 #
 from librarian import ValidationError, NoDublinCore,  ParseError, NoProvider
 from librarian import RDFNS
+from librarian.cover import WLCover
 from librarian import dcparser
 
 from xml.parsers.expat import ExpatError
         from librarian import fb2
         return fb2.transform(self, *args, **kwargs)
 
+    def as_cover(self, cover_class=None, *args, **kwargs):
+        if cover_class is None:
+            cover_class = WLCover
+        return cover_class(self.book_info, *args, **kwargs).output_file()
+
     def save_output_file(self, output_file, output_path=None,
             output_dir_path=None, make_author_dir=False, ext=None):
         if output_dir_path: