diff --git a/sxccd/sxccd_image.py b/sxccd/sxccd_image.py
index 5f7fa33..28959a1 100644
--- a/sxccd/sxccd_image.py
+++ b/sxccd/sxccd_image.py
@@ -1,10 +1,12 @@
 import argparse
-import sxccd
-import h5py
 import time
+
+import h5py
+import sxccd
 import numpy as np
 
-def takeImage( exp_ms, delay=0, prefix="images", nExp = 1, singleImage=True, bin=1 ):
+
+def takeImage(exp_ms, delay=0, prefix="images", nExp=1, singleImage=True, bin=1):
 
     sx = sxccd.Camera()
     sx.model()
@@ -13,10 +15,10 @@ def takeImage( exp_ms, delay=0, prefix="images", nExp = 1, singleImage=True, bin
     params = sx.parameters()
     width = params["width"]
     height = params["height"]
-    w = int( width / bin )
-    h = int( height / bin )
+    w = int(width / bin)
+    h = int(height / bin)
 
-    filename = prefix + "_" + str(exp_ms).zfill(6) + ".h5"
+    filename = f"{prefix}_{exp_ms:06d}.h5"
     f = h5py.File(filename, 'w')
     avg_set = f.create_dataset("avg", (h, w), dtype=np.float32)
     if singleImage:
@@ -25,15 +27,13 @@ def takeImage( exp_ms, delay=0, prefix="images", nExp = 1, singleImage=True, bin
 
     img_avg = np.zeros( (h,w), dtype=np.uint32)
 
-    if delay>0:
-        print("=========== camera exposure starts in "
-                + str(delay) + " sec "
-                + "===========" )
+    if delay > 0:
+        print(f"=========== camera exposure starts in {delay} sec ===========" )
         time.sleep(delay)
 
     for t in range(nExp):
         t1 = time.time()
-        img = sx.readPixelsDelayed( exp_ms, width, height, x_bin=bin, y_bin=bin,
+        img = sx.readPixelsDelayed(exp_ms, width, height, x_bin=bin, y_bin=bin,
                                 x_offset=0, y_offset=0, verbose=False)
         img_avg += img
 
@@ -41,13 +41,11 @@ def takeImage( exp_ms, delay=0, prefix="images", nExp = 1, singleImage=True, bin
             img_set[:,:,t] = img
 
         t2 = time.time()
-        print("image " + str(t+1) + " done in " + str(t2-t1) + " sec \a")
+        print(f"image {t+1} done in {t2-t1} sec \a")
 
     img_avg = img_avg.astype(np.float32) / nExp
     avg_set[:] = img_avg
-
-    print("========== done " + str(nExp) + " images ========== \a\a\a")
-
+    print(f"========== done {nExp} images ========== \a\a\a")
     f.close()
 
 
@@ -74,5 +72,5 @@ def takeImage( exp_ms, delay=0, prefix="images", nExp = 1, singleImage=True, bin
 
     args = parser.parse_args()
     print(args)
-    takeImage( exp_ms=args.exp, delay=args.delay, prefix=args.prefix,
-                nExp = args.num, singleImage=args.single, bin=args.bin )
+    takeImage(exp_ms=args.exp, delay=args.delay, prefix=args.prefix,
+                nExp = args.num, singleImage=args.single, bin=args.bin)
diff --git a/sxccd/sxccd_utils.py b/sxccd/sxccd_utils.py
index ec0d865..5af336f 100644
--- a/sxccd/sxccd_utils.py
+++ b/sxccd/sxccd_utils.py
@@ -1,15 +1,18 @@
 import numpy as np
 
-def decLH( LH ):
+
+def decLH(LH):
     return LH[0] + 256*LH[1]
 
-def dec2bytes( num, lg=2 ):
+
+def dec2bytes(num, lg=2):
     return (num).to_bytes(lg, byteorder="little")
 
-def dec2image( data, h, w ):
+
+def dec2image(data, h, w):
     img_sz = int(len(data)/2)
-    img = np.zeros( (img_sz,1), dtype=np.uint32)
+    img = np.zeros((img_sz,1), dtype=np.uint32)
     for i in range(img_sz):
         img[i] = decLH( data[2*i:(2*i+2)])
-    img = np.reshape( img, (h, w) )
+    img = np.reshape(img, (h, w))
     return img