diff --git a/escpos/escpos.py b/escpos/escpos.py
index 6bcfa40..639de99 100644
--- a/escpos/escpos.py
+++ b/escpos/escpos.py
@@ -49,7 +49,7 @@ class Escpos(object):
         """
         pass
 
-    def image(self, img_source, high_density_vertical = True, high_density_horizontal = True, impl = "bitImageRaster"):
+    def image(self, img_source, high_density_vertical=True, high_density_horizontal=True, impl="bitImageRaster"):
         """ Print an image
 
         :param img_source: PIL image or filename to load: `jpg`, `gif`, `png` or `bmp`
@@ -78,12 +78,11 @@ class Escpos(object):
         if impl == "bitImageColumn":
             # ESC *, column format bit image
             density_byte = (1 if high_density_horizontal else 0) + (32 if high_density_vertical else 0)
-            header = ESC + b"*" + six.int2byte(density_byte) + self._int_low_high( im.width, 2 )
-            outp = []
-            outp.append(ESC + b"3" + six.int2byte(16)) # Adjust line-feed size
+            header = ESC + b"*" + six.int2byte(density_byte) + self._int_low_high(im.width, 2)
+            outp = [ESC + b"3" + six.int2byte(16)]  # Adjust line-feed size
             for blob in im.to_column_format(high_density_vertical):
                 outp.append(header + blob + b"\n")
-            outp.append(ESC + b"2"); # Reset line-feed size
+            outp.append(ESC + b"2")  # Reset line-feed size
             self._raw(b''.join(outp))
 
     def _image_send_graphics_data(self, m, fn, data):
@@ -136,7 +135,7 @@ class Escpos(object):
             self.image(im)
             return
         # Native 2D code printing
-        cn = b'1' # Code type for QR code
+        cn = b'1'  # Code type for QR code
         # Select model: 1, 2 or micro.
         self._send_2d_code_data(six.int2byte(65), cn, six.int2byte(48 + model) + six.int2byte(0))
         # Set dot size.
diff --git a/escpos/image.py b/escpos/image.py
index 8dd46d4..1180614 100644
--- a/escpos/image.py
+++ b/escpos/image.py
@@ -10,6 +10,7 @@ This module contains the image format handler :py:class:`EscposImage`.
 
 from PIL import Image, ImageOps
 
+
 class EscposImage(object):
     """
     Load images in, and output ESC/POS formats.
@@ -64,7 +65,7 @@ class EscposImage(object):
         _, height_pixels = self._im.size
         return height_pixels
 
-    def to_column_format(self, high_density_vertical = True):
+    def to_column_format(self, high_density_vertical=True):
         """
         Extract slices of an image as equal-sized blobs of column-format data.
 
diff --git a/test/test_function_image.py b/test/test_function_image.py
index 17844a0..f60aa76 100644
--- a/test/test_function_image.py
+++ b/test/test_function_image.py
@@ -7,9 +7,15 @@
 :license: GNU GPL v3
 """
 
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
 import escpos.printer as printer
 from PIL import Image
 
+
 # Raster format print
 def test_bit_image_black():
     """
@@ -24,6 +30,7 @@ def test_bit_image_black():
     instance.image(im, impl="bitImageRaster")
     assert(instance.output == b'\x1dv0\x00\x01\x00\x01\x00\x80')
 
+
 def test_bit_image_white():
     """
     Test printing solid white bit image (raster)
@@ -32,6 +39,7 @@ def test_bit_image_white():
     instance.image('test/resources/canvas_white.png', impl="bitImageRaster")
     assert(instance.output == b'\x1dv0\x00\x01\x00\x01\x00\x00')
 
+
 def test_bit_image_both():
     """
     Test printing black/white bit image (raster)
@@ -40,6 +48,7 @@ def test_bit_image_both():
     instance.image('test/resources/black_white.png', impl="bitImageRaster")
     assert(instance.output == b'\x1dv0\x00\x01\x00\x02\x00\xc0\x00')
 
+
 def test_bit_image_transparent():
     """
     Test printing black/transparent bit image (raster)
@@ -48,6 +57,7 @@ def test_bit_image_transparent():
     instance.image('test/resources/black_transparent.png', impl="bitImageRaster")
     assert(instance.output == b'\x1dv0\x00\x01\x00\x02\x00\xc0\x00')
 
+
 # Column format print
 def test_bit_image_colfmt_black():
     """
@@ -57,6 +67,7 @@ def test_bit_image_colfmt_black():
     instance.image('test/resources/canvas_black.png', impl="bitImageColumn")
     assert(instance.output == b'\x1b3\x10\x1b*!\x01\x00\x80\x00\x00\x0a\x1b2')
 
+
 def test_bit_image_colfmt_white():
     """
     Test printing solid white bit image (column format)
@@ -65,6 +76,7 @@ def test_bit_image_colfmt_white():
     instance.image('test/resources/canvas_white.png', impl="bitImageColumn")
     assert(instance.output == b'\x1b3\x10\x1b*!\x01\x00\x00\x00\x00\x0a\x1b2')
 
+
 def test_bit_image_colfmt_both():
     """
     Test printing black/white bit image (column format)
@@ -73,6 +85,7 @@ def test_bit_image_colfmt_both():
     instance.image('test/resources/black_white.png', impl="bitImageColumn")
     assert(instance.output == b'\x1b3\x10\x1b*!\x02\x00\x80\x00\x00\x80\x00\x00\x0a\x1b2')
 
+
 def test_bit_image_colfmt_transparent():
     """
     Test printing black/transparent bit image (column format)
@@ -81,6 +94,7 @@ def test_bit_image_colfmt_transparent():
     instance.image('test/resources/black_transparent.png', impl="bitImageColumn")
     assert(instance.output == b'\x1b3\x10\x1b*!\x02\x00\x80\x00\x00\x80\x00\x00\x0a\x1b2')
 
+
 # Graphics print
 def test_graphics_black():
     """
@@ -90,6 +104,7 @@ def test_graphics_black():
     instance.image('test/resources/canvas_black.png', impl="graphics")
     assert(instance.output == b'\x1d(L\x0b\x000p0\x01\x011\x01\x00\x01\x00\x80\x1d(L\x02\x0002')
 
+
 def test_graphics_white():
     """
     Test printing solid white graphics
@@ -98,6 +113,7 @@ def test_graphics_white():
     instance.image('test/resources/canvas_white.png', impl="graphics")
     assert(instance.output == b'\x1d(L\x0b\x000p0\x01\x011\x01\x00\x01\x00\x00\x1d(L\x02\x0002')
 
+
 def test_graphics_both():
     """
     Test printing black/white graphics
@@ -106,6 +122,7 @@ def test_graphics_both():
     instance.image('test/resources/black_white.png', impl="graphics")
     assert(instance.output == b'\x1d(L\x0c\x000p0\x01\x011\x02\x00\x02\x00\xc0\x00\x1d(L\x02\x0002')
 
+
 def test_graphics_transparent():
     """
     Test printing black/transparent graphics
diff --git a/test/test_function_qr_native.py b/test/test_function_qr_native.py
index 7f24e42..a3355ca 100644
--- a/test/test_function_qr_native.py
+++ b/test/test_function_qr_native.py
@@ -16,6 +16,7 @@ from nose.tools import raises
 import escpos.printer as printer
 from escpos.constants import QR_ECLEVEL_H, QR_MODEL_1
 
+
 def test_defaults():
     """Test QR code with defaults"""
     instance = printer.Dummy()
@@ -24,12 +25,14 @@ def test_defaults():
         b'(k\x07\x001P01234\x1d(k\x03\x001Q0'
     assert(instance.output == expected)
 
+
 def test_empty():
     """Test QR printing blank code"""
     instance = printer.Dummy()
     instance.qr("", native=True)
     assert(instance.output == b'')
 
+
 def test_ec():
     """Test QR error correction setting"""
     instance = printer.Dummy()
@@ -38,6 +41,7 @@ def test_ec():
         b'(k\x07\x001P01234\x1d(k\x03\x001Q0'
     assert(instance.output == expected)
 
+
 def test_size():
     """Test QR box size"""
     instance = printer.Dummy()
@@ -46,6 +50,7 @@ def test_size():
         b'(k\x07\x001P01234\x1d(k\x03\x001Q0'
     assert(instance.output == expected)
 
+
 def test_model():
     """Test QR model"""
     instance = printer.Dummy()
@@ -54,24 +59,28 @@ def test_model():
         b'(k\x07\x001P01234\x1d(k\x03\x001Q0'
     assert(instance.output == expected)
 
+
 @raises(ValueError)
 def test_invalid_ec():
     """Test invalid QR error correction"""
     instance = printer.Dummy()
     instance.qr("1234", native=True, ec=-1)
 
+
 @raises(ValueError)
 def test_invalid_size():
     """Test invalid QR size"""
     instance = printer.Dummy()
     instance.qr("1234", native=True, size=0)
 
+
 @raises(ValueError)
 def test_invalid_model():
     """Test invalid QR model"""
     instance = printer.Dummy()
     instance.qr("1234", native=True, model="Hello")
 
+
 def test_image():
     """Test QR as image"""
     instance = printer.Dummy()
@@ -82,6 +91,7 @@ def test_image():
         b'i(\x7f<\xa8A \xd8]\'\xc4]y\xf8]E\x80Ar\x94\x7fR@\x00\x00\x00'
     assert(instance.output == expected)
 
+
 @raises(ValueError)
 def test_image_invalid_model():
     """Test unsupported QR model as image"""
diff --git a/test/test_image.py b/test/test_image.py
index 6612703..fd49797 100644
--- a/test/test_image.py
+++ b/test/test_image.py
@@ -10,6 +10,7 @@ converted to ESC/POS column & raster formats.
 
 from escpos.image import EscposImage
 
+
 def test_image_black():
     """
     Test rendering solid black image
@@ -17,6 +18,7 @@ def test_image_black():
     for img_format in ['png', 'jpg', 'gif']:
         _load_and_check_img('canvas_black.' + img_format, 1, 1, b'\x80', [b'\x80'])
 
+
 def test_image_black_transparent():
     """
     Test rendering black/transparent image
@@ -24,6 +26,7 @@ def test_image_black_transparent():
     for img_format in ['png', 'gif']:
         _load_and_check_img('black_transparent.' + img_format, 2, 2, b'\xc0\x00', [b'\x80\x80'])
 
+
 def test_image_black_white():
     """
     Test rendering black/white image
@@ -31,6 +34,7 @@ def test_image_black_white():
     for img_format in ['png', 'jpg', 'gif']:
         _load_and_check_img('black_white.' + img_format, 2, 2, b'\xc0\x00', [b'\x80\x80'])
 
+
 def test_image_white():
     """
     Test rendering solid white image
@@ -38,11 +42,12 @@ def test_image_white():
     for img_format in ['png', 'jpg', 'gif']:
         _load_and_check_img('canvas_white.' + img_format, 1, 1, b'\x00', [b'\x00'])
 
+
 def _load_and_check_img(filename, width_expected, height_expected, raster_format_expected, column_format_expected):
     """
     Load an image, and test whether raster & column formatted output, sizes, etc match expectations.
     """
-    im = EscposImage('test/resources/' +  filename)
+    im = EscposImage('test/resources/' + filename)
     assert(im.width == width_expected)
     assert(im.height == height_expected)
     assert(im.to_raster_format() == raster_format_expected)