diff --git a/convert_dhr.py b/convert_dhr.py
index 9ba7801..4e95eb8 100644
--- a/convert_dhr.py
+++ b/convert_dhr.py
@@ -10,15 +10,15 @@ import screen as screen_py
 import image as image_py
 
 
-def  _output(out_image: Image, args):
-   if args.show_output:
+def _output(out_image: Image, args):
+    if args.show_output:
         out_image.show()
 
-   if args.save_preview:
-       # Save Double hi-res image
-       outfile = os.path.join(
-           os.path.splitext(args.output)[0] + "-preview.png")
-       out_image.save(outfile, "PNG")
+    if args.save_preview:
+        # Save Double hi-res image
+        outfile = os.path.join(
+            os.path.splitext(args.output)[0] + "-preview.png")
+        out_image.save(outfile, "PNG")
 
 
 def _write(screen: screen_py.DHGRScreen, bitmap: np.ndarray, args):
@@ -57,6 +57,7 @@ def convert(screen: screen_py.DHGRNTSCScreen, image: Image, args):
     _output(out_image, args)
     _write(screen, bitmap, args)
 
+
 def convert_mono(screen: screen_py.DHGRScreen, image: Image, args):
     image = image.convert("1")
 
diff --git a/image.py b/image.py
index 622b61b..40a8bc3 100644
--- a/image.py
+++ b/image.py
@@ -46,5 +46,6 @@ def resize(
     else:
         return res
 
+
 def resize_mono(image: Image, x_res, y_res) -> Image:
     return image.resize((x_res, y_res), Image.LANCZOS)
diff --git a/screen.py b/screen.py
index 681bbcc..32108ca 100644
--- a/screen.py
+++ b/screen.py
@@ -1,6 +1,5 @@
 """Representation of Apple II screen memory."""
 
-import math
 import numpy as np
 import palette as palette_py
 
@@ -111,6 +110,7 @@ class DHGRScreen:
             self.main[addr:addr + 40] = main_col[y, :]
         return
 
+
 class DHGRNTSCScreen(DHGRScreen):
     def __init__(self, palette: palette_py.Palette):
         self.palette = palette