diff --git a/changelog/135.feature.rst b/changelog/135.feature.rst
new file mode 100644
index 00000000..52b57e55
--- /dev/null
+++ b/changelog/135.feature.rst
@@ -0,0 +1,10 @@
+Several functions have been updated to accept either numpy array or sunpy map inputs.
+The following functions now accept either a numpy array or sunpy map, and return the same data type:
+
+- `sunkit_image.enhance.mgn`
+- `sunkit_image.trace.bandpass_filter`
+- `sunkit_image.trace.smooth`
+
+The following functions now accept either a numpy array or sunpy map, and their return type is unchanged:
+
+- `sunkit_image.trace.occult2`
diff --git a/sunkit_image/enhance.py b/sunkit_image/enhance.py
index ff243e48..e8fa9590 100644
--- a/sunkit_image/enhance.py
+++ b/sunkit_image/enhance.py
@@ -6,9 +6,12 @@
 import numpy as np
 import scipy.ndimage as ndimage
 
+from sunkit_image.utils.decorators import accept_array_or_map
+
 __all__ = ["mgn"]
 
 
+@accept_array_or_map(arg_name="data")
 def mgn(
     data,
     sigma=[1.25, 2.5, 5, 10, 20, 40],
@@ -41,7 +44,7 @@ def mgn(
 
     Parameters
     ----------
-    data : `numpy.ndarray`
+    data : `numpy.ndarray`, `sunpy.map.GenericMap`
         Image to be transformed.
     sigma : `list`, optional
         Range of Gaussian widths (i.e. the standard deviation of the Gaussian kernel) to transform over.
@@ -72,8 +75,9 @@ def mgn(
 
     Returns
     -------
-    `numpy.ndarray`
-        Normalized image.
+    `numpy.ndarray`, `sunpy.map.GenericMap`
+        Normalized image. If a map is input, a map is returned with new data
+        and the same metadata.
 
     References
     ----------
diff --git a/sunkit_image/tests/conftest.py b/sunkit_image/tests/conftest.py
index 794dc265..75bc61e4 100644
--- a/sunkit_image/tests/conftest.py
+++ b/sunkit_image/tests/conftest.py
@@ -8,6 +8,7 @@
 
 import astropy
 import astropy.config.paths
+import sunpy.data.sample
 import sunpy.map
 from astropy.utils.data import get_pkg_data_filename
 from sunpy.coordinates import Helioprojective, get_earth
@@ -155,3 +156,13 @@ def granule_minimap3():
     )
     map = sunpy.map.GenericMap(arr, header)
     return map
+
+
+@pytest.fixture(params=["array", "map"])
+@pytest.mark.remote_data
+def aia_171(request):
+    smap = sunpy.map.Map(sunpy.data.sample.AIA_171_IMAGE)
+    if request.param == "map":
+        return smap
+    elif request.param == "array":
+        return smap.data
diff --git a/sunkit_image/tests/figure_hashes_mpl_372_ft_261_sunkit_image_dev_sunpy_500.json b/sunkit_image/tests/figure_hashes_mpl_372_ft_261_sunkit_image_dev_sunpy_500.json
index 05e308a6..e69f4d65 100644
--- a/sunkit_image/tests/figure_hashes_mpl_372_ft_261_sunkit_image_dev_sunpy_500.json
+++ b/sunkit_image/tests/figure_hashes_mpl_372_ft_261_sunkit_image_dev_sunpy_500.json
@@ -1,6 +1,8 @@
 {
-    "sunkit_image.tests.test_enhance.test_mgn": "4ef8a14c6b3290280b6fc9bc0748c8aa170760b2d43a5bbd67bb4d46ffd5408e",
-    "sunkit_image.tests.test_radial.test_fig_nrgf": "52b448fa9d845841066d71a1fc6e7bfc471a658d726af1cf16403ddb858fcfc0",
-    "sunkit_image.tests.test_radial.test_fig_fnrgf": "62621426ff8c3ee03cb1de004f9e08f63c4869dbd8b55d440adc73c74bfc5bcc",
-    "sunkit_image.tests.test_trace.test_occult2_fig": "c5ff1416cb51dc51ad1705174e5b13f8cb02486dc3c58fd79dc1b80534f6caf5"
-  }
+  "sunkit_image.tests.test_enhance.test_mgn[array]": "67b17ac7c343a1d568d9dfa2bb12e0041e2fc53e8ca1c0e1c2c7693eda2bd0d8",
+  "sunkit_image.tests.test_enhance.test_mgn[map]": "4ef8a14c6b3290280b6fc9bc0748c8aa170760b2d43a5bbd67bb4d46ffd5408e",
+  "sunkit_image.tests.test_radial.test_fig_nrgf": "52b448fa9d845841066d71a1fc6e7bfc471a658d726af1cf16403ddb858fcfc0",
+  "sunkit_image.tests.test_radial.test_fig_fnrgf": "62621426ff8c3ee03cb1de004f9e08f63c4869dbd8b55d440adc73c74bfc5bcc",
+  "sunkit_image.tests.test_trace.test_occult2_fig[array]": "c5ff1416cb51dc51ad1705174e5b13f8cb02486dc3c58fd79dc1b80534f6caf5",
+  "sunkit_image.tests.test_trace.test_occult2_fig[map]": "c5ff1416cb51dc51ad1705174e5b13f8cb02486dc3c58fd79dc1b80534f6caf5"
+}
diff --git a/sunkit_image/tests/test_enhance.py b/sunkit_image/tests/test_enhance.py
index db58e1b7..a424b680 100644
--- a/sunkit_image/tests/test_enhance.py
+++ b/sunkit_image/tests/test_enhance.py
@@ -8,19 +8,13 @@
 from sunkit_image.tests.helpers import figure_test
 
 
-@pytest.fixture
-@pytest.mark.remote_data
-def smap():
-    return sunpy.map.Map(sunpy.data.sample.AIA_171_IMAGE)
-
-
 @figure_test
 @pytest.mark.remote_data
-def test_mgn(smap):
-    out = enhance.mgn(smap.data)
-    out = sunpy.map.Map(out, smap.meta)
-
-    out.plot()
+def test_mgn(aia_171):
+    out = enhance.mgn(aia_171)
+    assert type(out) == type(aia_171)
+    if isinstance(out, sunpy.map.GenericMap):
+        out.plot()
 
 
 @pytest.fixture
diff --git a/sunkit_image/tests/test_trace.py b/sunkit_image/tests/test_trace.py
index 34a02ad3..659c3a23 100644
--- a/sunkit_image/tests/test_trace.py
+++ b/sunkit_image/tests/test_trace.py
@@ -4,6 +4,7 @@
 import numpy as np
 import pytest
 
+import sunpy.map
 from astropy.io import fits
 
 import sunkit_image.data.test as data
@@ -19,13 +20,20 @@
 )
 
 
-@pytest.fixture
+@pytest.fixture(params=["array", "map"])
 @pytest.mark.remote_data
-def image_remote():
+def image_remote(request):
     with warnings.catch_warnings():
         warnings.simplefilter("ignore", category=fits.verify.VerifyWarning)
-        im = fits.getdata("http://data.sunpy.org/sunkit-image/trace_1998-05-19T22:21:43.000_171_1024.fits")
-        return im
+        data, header = fits.getdata(
+            "http://data.sunpy.org/sunkit-image/trace_1998-05-19T22:21:43.000_171_1024.fits", header=True
+        )
+        if request.param == "map":
+            return sunpy.map.Map((data, header))
+        elif request.param == "array":
+            return data
+        else:
+            raise ValueError(f"Invalid request parameter {request.param}")
 
 
 @pytest.fixture
@@ -161,16 +169,18 @@ def test_map():
 
 
 @pytest.fixture
-def image():
+def test_map_ones():
     return np.ones((4, 4), dtype=np.float32)
 
 
-def test_bandpass_filter(image, test_map):
+def test_bandpass_filter_ones(test_map_ones):
     expect = np.zeros((4, 4))
-    result = bandpass_filter(image)
+    result = bandpass_filter(test_map_ones)
 
     assert np.allclose(expect, result)
 
+
+def test_bandpass_filter(test_map):
     expect = np.array(
         [
             [0.0, 0.0, 0.0, 0.0],
@@ -181,22 +191,30 @@ def test_bandpass_filter(image, test_map):
     )
 
     result = bandpass_filter(test_map)
-
     assert np.allclose(expect, result)
 
-    with pytest.raises(ValueError) as record:
-        _ = bandpass_filter(image, 5, 1)
 
-    assert str(record.value) == "nsm1 should be less than nsm2"
+@pytest.mark.remote_data
+def test_bandpass_filter_output(aia_171):
+    # Check that bandpass filter works with both arrays and maps
+    result = bandpass_filter(aia_171)
+    assert type(result) == type(aia_171)
+
+
+def test_bandpass_filter_error(test_map_ones):
+    with pytest.raises(ValueError, match="nsm1 should be less than nsm2"):
+        bandpass_filter(test_map_ones, 5, 1)
+
 
+def test_smooth_ones(test_map_ones):
+    filtered = smooth(test_map_ones, 1)
+    assert np.allclose(filtered, test_map_ones)
 
-def test_smooth(image, test_map):
-    filtered = smooth(image, 1)
-    assert np.allclose(filtered, image)
+    filtered = smooth(test_map_ones, 4)
+    assert np.allclose(filtered, test_map_ones)
 
-    filtered = smooth(image, 4)
-    assert np.allclose(filtered, image)
 
+def test_smooth(test_map):
     filtered = smooth(test_map, 1)
     assert np.allclose(filtered, test_map)
 
@@ -213,7 +231,14 @@ def test_smooth(image, test_map):
     assert np.allclose(filtered, expect)
 
 
-def test_erase_loop_in_image(image, test_map):
+@pytest.mark.remote_data
+def test_smooth_output(aia_171):
+    # Check that smooth works with both arrays and maps
+    result = smooth(aia_171, 1)
+    assert type(result) == type(aia_171)
+
+
+def test_erase_loop_in_image(test_map_ones, test_map):
     # The starting point of a dummy loop
     istart = 0
     jstart = 1
@@ -223,7 +248,7 @@ def test_erase_loop_in_image(image, test_map):
     xloop = [1, 2, 3]
     yloop = [1, 1, 1]
 
-    result = _erase_loop_in_image(image, istart, jstart, width, xloop, yloop)
+    result = _erase_loop_in_image(test_map_ones, istart, jstart, width, xloop, yloop)
 
     expect = np.array([[0.0, 0.0, 0.0, 1.0], [0.0, 0.0, 0.0, 1.0], [0.0, 0.0, 0.0, 1.0], [0.0, 0.0, 0.0, 1.0]])
 
diff --git a/sunkit_image/trace.py b/sunkit_image/trace.py
index 6db196c1..1e157a7a 100644
--- a/sunkit_image/trace.py
+++ b/sunkit_image/trace.py
@@ -6,6 +6,8 @@
 import numpy as np
 from scipy import interpolate
 
+from sunkit_image.utils.decorators import accept_array_or_map
+
 __all__ = [
     "occult2",
     "bandpass_filter",
@@ -13,6 +15,7 @@
 ]
 
 
+@accept_array_or_map(arg_name="image", output_to_map=False)
 def occult2(image, nsm1, rmin, lmin, nstruc, ngap, qthresh1, qthresh2):
     """
     Implements the Oriented Coronal CUrved Loop Tracing (OCCULT-2) algorithm
@@ -20,7 +23,7 @@ def occult2(image, nsm1, rmin, lmin, nstruc, ngap, qthresh1, qthresh2):
 
     Parameters
     ----------
-    image : `numpy.ndarray`
+    image : `numpy.ndarray`, `sunpy.map.GenericMap`
         Image in which loops are to be detected.
     nsm1 : `int`
         Low pass filter boxcar smoothing constant.
@@ -44,7 +47,7 @@ def occult2(image, nsm1, rmin, lmin, nstruc, ngap, qthresh1, qthresh2):
     -------
     `list`
         A list of all loop where each element is itself a list of points containing
-        ``x`` and ``y`` coordinates for each point.
+        ``x`` and ``y`` pixel coordinates for each point.
 
     References
     ----------
@@ -217,13 +220,14 @@ def occult2(image, nsm1, rmin, lmin, nstruc, ngap, qthresh1, qthresh2):
 
 
 # The functions below this are subroutines for the OCCULT 2.
+@accept_array_or_map(arg_name="image")
 def bandpass_filter(image, nsm1=1, nsm2=3):
     """
     Applies a band pass filter to the image.
 
     Parameters
     ----------
-    image : `numpy.ndarray`
+    image : `numpy.ndarray`, `sunpy.map.GenericMap`
         Image to be filtered.
     nsm1 : `int`
         Low pass filter boxcar smoothing constant.
@@ -236,7 +240,8 @@ def bandpass_filter(image, nsm1=1, nsm2=3):
     Returns
     -------
     `numpy.ndarray`
-        Bandpass filtered image.
+        Bandpass filtered image. If a map is input, a map is returned with new data
+        and the same metadata.
     """
     if nsm1 >= nsm2:
         raise ValueError("nsm1 should be less than nsm2")
@@ -248,13 +253,14 @@ def bandpass_filter(image, nsm1=1, nsm2=3):
         return smooth(image, nsm1, "replace") - smooth(image, nsm2, "replace")
 
 
+@accept_array_or_map(arg_name="image")
 def smooth(image, width, nanopt="replace"):
     """
     Python implementation of the IDL's ``smooth``.
 
     Parameters
     ----------
-    image : `numpy.ndarray`
+    image : `numpy.ndarray`, `sunpy.map.GenericMap`
         Image to be filtered.
     width : `int`
         Width of the boxcar window. The `width` should always be odd but if even value is given then
@@ -264,8 +270,9 @@ def smooth(image, width, nanopt="replace"):
 
     Returns
     -------
-    `numpy.ndarray`
-        Smoothed image.
+    `numpy.ndarray`, `sunpy.map.GenericMap`
+        Smoothed image. If a map is input, a map is returned with new data
+        and the same metadata.
 
     References
     ----------
diff --git a/sunkit_image/utils/decorators.py b/sunkit_image/utils/decorators.py
new file mode 100644
index 00000000..48b8e910
--- /dev/null
+++ b/sunkit_image/utils/decorators.py
@@ -0,0 +1,56 @@
+import inspect
+from typing import Union, Callable
+
+import numpy as np
+
+from sunpy.map import GenericMap, Map
+
+
+def accept_array_or_map(*, arg_name: str, output_to_map=True) -> Callable[[Callable], Callable]:
+    """
+    Decorator that allows a function to accept an array or a
+    `sunpy.map.GenericMap` as an argument.
+
+    This can be applied to functions that:
+
+    - Take a single array or map as input
+    - Return a single array that has the same pixel coordinates
+      as the input array.
+
+    Parameters
+    ----------
+    arg_name : `str`
+        Name of data/map argument in function signature.
+    output_to_map : `bool`
+        If `True` (the default), convert the function return to a map if a map
+        is given as input. For this to work the decorated function must return
+        an array where pixels have the same coordinates as the input map data.
+    """
+
+    def decorate(f: Callable) -> Callable:
+        sig = inspect.signature(f)
+        if arg_name not in sig.parameters:
+            raise RuntimeError(f"Could not find '{arg_name}' in function signature")
+
+        def inner(*args, **kwargs) -> Union[np.ndarray, GenericMap]:
+            sig_bound = sig.bind(*args, **kwargs)
+            map_arg = sig_bound.arguments[arg_name]
+            if isinstance(map_arg, GenericMap):
+                map_in = True
+                sig_bound.arguments[arg_name] = map_arg.data
+            elif isinstance(map_arg, np.ndarray):
+                map_in = False
+            else:
+                raise ValueError(f"'{arg_name}' argument must be a sunpy map or numpy array (got type {type(map_arg)})")
+
+            # Run decorated function
+            array_out = f(*sig_bound.args, **sig_bound.kwargs)
+
+            if map_in and output_to_map:
+                return Map(array_out, map_arg.meta)
+            else:
+                return array_out
+
+        return inner
+
+    return decorate