diff --git a/brother_ql/brother_ql_create.py b/brother_ql/brother_ql_create.py
index d5c1516..631fd96 100755
--- a/brother_ql/brother_ql_create.py
+++ b/brother_ql/brother_ql_create.py
@@ -35,7 +35,7 @@ def main():
     parser.add_argument('--model', '-m', default='QL-500', help='The printer model to use. Check available ones with `brother_ql_info list-models`.')
     parser.add_argument('--label-size', '-s', default='62', help='The label size (and kind) to use. Check available ones with `brother_ql_info list-label-sizes`.')
     parser.add_argument('--rotate', '-r', choices=('0', '90', '180', '270'), default='auto', help='Rotate the image (counterclock-wise) by this amount of degrees.')
-    parser.add_argument('--threshold', '-t', type=float, default=30.0, help='The threshold value (in percent) to discriminate between black and white pixels.')
+    parser.add_argument('--threshold', '-t', type=float, default=70.0, help='The threshold value (in percent) to discriminate between black and white pixels.')
     parser.add_argument('--no-cut', dest='cut', action='store_false', help="Don't cut the tape after printing the label.")
     parser.add_argument('--loglevel', type=lambda x: getattr(logging, x), default=logging.WARNING, help='Set to DEBUG for verbose debugging output to stderr.')
     parser.add_argument('--cores', '-c', type=int, default=defaultCores, help='The number of cores to use on creating the bin file.')
@@ -65,7 +65,7 @@ def main():
 
     args.outfile.write(qlr.data)
 
-def create_label(qlr, image, label_size, cores, threshold=30, cut=True, **kwargs):
+def create_label(qlr, image, label_size, cores, threshold=70, cut=True, **kwargs):
 
     label_specs = label_type_specs[label_size]
     dots_printable = label_specs['dots_printable']
@@ -111,6 +111,8 @@ def create_label(qlr, image, label_size, cores, threshold=30, cut=True, **kwargs
         im = new_im
 
     im = PIL.ImageOps.invert(im)
+
+    threshold = 100.0 - threshold
     threshold = min(255, max(0, int(threshold/100.0 * 255))) # from percent to pixel val
     im = im.point(lambda x: 0 if x < threshold else 255, mode="1")
 
diff --git a/brother_ql/raster.py b/brother_ql/raster.py
index 86a1820..da85f07 100644
--- a/brother_ql/raster.py
+++ b/brother_ql/raster.py
@@ -20,11 +20,11 @@ from .devicedependent import models, \
 
 from . import BrotherQLError, BrotherQLUnsupportedCmd, BrotherQLUnknownModel, BrotherQLRasterError
 
-import multiprocessing, ctypes
+import multiprocessing
 
-from multiprocessing import Process, Manager, Array
+from multiprocessing import Process, Manager
 
-from cStringIO import StringIO
+from io import BytesIO
 
 logger = logging.getLogger(__name__)
 
@@ -175,7 +175,7 @@ class BrotherQLRaster(object):
             nbpr = number_bytes_per_row['default']
         return nbpr*8
 
-    def add_raster_data(self, image, cores):
+    def add_raster_data(self, image, cores=1):
         """ image: Pillow Image() """
         logger.info("raster_image_size: {0}x{1}".format(*image.size))
         image = image.transpose(Image.FLIP_LEFT_RIGHT)
@@ -189,9 +189,7 @@ class BrotherQLRaster(object):
         row_len = image.size[0]//8
         start = 0
 
-        file_str = StringIO()
-
-        logger.debug("Frame " + str(frame_len) + " Row " + str(row_len))
+        file_str = BytesIO()
          
         if cores > 1:
 
@@ -242,12 +240,9 @@ class BrotherQLRaster(object):
             while start + row_len <= frame_len:
                 row = frame[start:start+row_len]
                 start += row_len
-                #self.data += b'\x67\x00' # g 0x00
                 file_str.write(b'\x67\x00')
                 if self._compression:
                     row = packbits.encode(row)
-                #self.data += bytes([len(row)])
-                #self.data += row
                 file_str.write(bytes([len(row)]))
                 file_str.write(row)
 
@@ -262,7 +257,7 @@ class BrotherQLRaster(object):
 
     def processFrame(self, start, row_len, frame_len, frame, index, g_data):
 
-        file_str = StringIO()
+        file_str = BytesIO()
         while start + row_len <= frame_len:
             row = frame[start:start+row_len]
             start += row_len