diff --git a/csst_proto/flip_image.py b/csst_proto/flip_image.py
index d10254ccba585cea9a3feca6ad75d0a8a9c0b57b..818fc097805b2956f7e66eaa97f0944cc8729c7e 100644
--- a/csst_proto/flip_image.py
+++ b/csst_proto/flip_image.py
@@ -1,4 +1,6 @@
 import numpy as np
+import joblib
+import multiprocessing
 from . import PACKAGE_PATH
 
 
@@ -50,3 +52,17 @@ def read_test_image():
     fp_img = PACKAGE_PATH + "/data/test_image.txt"
     print("reading file {} ...".format(fp_img))
     return np.loadtxt(fp_img, dtype=int)
+
+
+def flip_multiple_images_mp(imgs: list, n_jobs: int) -> list:
+    """ parallel with multiprocessing """
+    with multiprocessing.Pool(n_jobs) as p:
+        results = p.map(flip_image, imgs)
+    return results
+
+
+def flip_multiple_images_jl(imgs: list, n_jobs: int) -> list:
+    """ parallel with joblib """
+    return joblib.Parallel(n_jobs=n_jobs)(
+        joblib.delayed(flip_image)(img) for img in imgs
+    )
diff --git a/csst_proto/scratch.py b/csst_proto/scratch.py
deleted file mode 100644
index 394e31fcfb38f8258810d6964319ec320891e875..0000000000000000000000000000000000000000
--- a/csst_proto/scratch.py
+++ /dev/null
@@ -1,33 +0,0 @@
-import numpy as np
-
-
-def print_some_numbers(start: int, stop=10):
-    """ this function prints some numbers
-
-    Parameters
-    ----------
-    start: int
-        start number
-    stop: int
-        stop number
-
-    Notes
-    -----
-    this algorithm ...
-    """
-    for i in np.arange(start, stop):
-        print(i)
-    return
-
-
-class AClass:
-    def __init__(self):
-        self.a = 1
-
-    def print_a(self):
-        if True:
-            print(self.a)
-
-
-if __name__ == "__main__":
-    print_some_numbers(start=1, stop=5)
diff --git a/tests/test_flip_image.py b/tests/test_flip_image.py
index a657430ac458b10f771fefd41c2c4f60ca7b7727..a76b4e0acafea10bc15bddf5c4d417fdc42c6d23 100644
--- a/tests/test_flip_image.py
+++ b/tests/test_flip_image.py
@@ -3,6 +3,7 @@ import unittest
 import numpy as np
 
 from csst_proto.top_level_interface import flip_image, read_test_image
+from csst_proto.flip_image import flip_multiple_images_jl, flip_multiple_images_mp
 
 
 class FlipImageTestCase(unittest.TestCase):
@@ -15,3 +16,23 @@ class FlipImageTestCase(unittest.TestCase):
         # the code fails for 1D array
         with self.assertRaises(AssertionError):
             flip_image(np.array([1, 2, 3, 4]))
+
+    def test_flip_multiple_images_mp(self):
+        """ test flip multiple images with multiprocessing """
+        n_jobs = 10
+        imgs = [read_test_image() for i_job in range(n_jobs)]
+        flipped_imgs = flip_multiple_images_mp(imgs, n_jobs)
+        for i_job in range(n_jobs):
+            self.assertTrue(
+                np.all(flipped_imgs[i_job] == np.array([[4, 3], [2, 1]]))
+            )
+
+    def test_flip_multiple_images_jl(self):
+        """ test flip multiple images with joblib """
+        n_jobs = 10
+        imgs = [read_test_image() for i_job in range(n_jobs)]
+        flipped_imgs = flip_multiple_images_jl(imgs, n_jobs)
+        for i_job in range(n_jobs):
+            self.assertTrue(
+                np.all(flipped_imgs[i_job] == np.array([[4, 3], [2, 1]]))
+            )