diff --git a/src/pynwb/ophys.py b/src/pynwb/ophys.py
index 2240c8a05..1eeaad766 100644
--- a/src/pynwb/ophys.py
+++ b/src/pynwb/ophys.py
@@ -277,6 +277,35 @@ def add_roi(self, **kwargs):
             rkwargs['voxel_mask'] = voxel_mask
         return super(PlaneSegmentation, self).add_row(**rkwargs)
 
+    @staticmethod
+    def pixel_to_image(pixel_mask):
+        """
+        Converts a 2D pixel_mask of a ROI into an image_mask.
+        """
+        image_matrix = np.zeros(np.shape(pixel_mask))
+        npmask = np.asarray(pixel_mask)
+        x_coords = npmask[:, 0].astype(np.int)
+        y_coords = npmask[:, 1].astype(np.int)
+        weights = npmask[:, -1]
+        image_matrix[y_coords, x_coords] = weights
+        return image_matrix
+
+    @staticmethod
+    def image_to_pixel(image_mask):
+        """
+        Converts an image_mask of a ROI into a pixel_mask
+        """
+        pixel_mask = []
+        it = np.nditer(image_mask, flags=['multi_index'])
+        while not it.finished:
+            weight = it[0][()]
+            if weight > 0:
+                x = it.multi_index[0]
+                y = it.multi_index[1]
+                pixel_mask.append([x, y, weight])
+            it.iternext()
+        return pixel_mask
+
     @docval({'name': 'description', 'type': str, 'doc': 'a brief description of what the region is'},
             {'name': 'region', 'type': (slice, list, tuple), 'doc': 'the indices of the table', 'default': slice(None)},
             {'name': 'name', 'type': str, 'doc': 'the name of the ROITableRegion', 'default': 'rois'})
diff --git a/tests/unit/test_ophys.py b/tests/unit/test_ophys.py
index bd7632d80..4d1f6372b 100644
--- a/tests/unit/test_ophys.py
+++ b/tests/unit/test_ophys.py
@@ -157,6 +157,11 @@ def getBoilerPlateObjects(self):
                           300., 'indicator', 'location', (1, 2, 1, 2, 3), 4.0, 'unit', 'reference_frame')
         return iSS, ip
 
+    def create_basic_plane_segmentation(self):
+        """Creates a basic plane segmentation used for testing"""
+        iSS, ip = self.getBoilerPlateObjects()
+        return PlaneSegmentation('description', ip, 'test_name', iSS)
+
     def test_init(self):
         w, h = 5, 5
         img_mask = [[[1.0 for x in range(w)] for y in range(h)], [[2.0 for x in range(w)] for y in range(h)]]
@@ -220,15 +225,33 @@ def test_init_voxel_mask(self):
     def test_init_3d_image_mask(self):
         img_masks = np.random.randn(2, 20, 30, 4)
 
-        iSS, ip = self.getBoilerPlateObjects()
-
-        pS = PlaneSegmentation('description', ip, 'test_name', iSS)
+        pS = self.create_basic_plane_segmentation()
         pS.add_roi(image_mask=img_masks[0])
         pS.add_roi(image_mask=img_masks[1])
 
         self.assertTrue(np.allclose(pS['image_mask'][0], img_masks[0]))
         self.assertTrue(np.allclose(pS['image_mask'][1], img_masks[1]))
 
+    def test_conversion_of_2d_pixel_mask_to_image_mask(self):
+        pixel_mask = [[0, 0, 1.0], [1, 0, 2.0], [2, 0, 2.0]]
+
+        pS = self.create_basic_plane_segmentation()
+
+        img_mask = pS.pixel_to_image(pixel_mask)
+        np.testing.assert_allclose(img_mask, np.asarray([[1, 2, 2.0],
+                                                         [0, 0, 0.0],
+                                                         [0, 0, 0.0]]))
+
+    def test_conversion_of_2d_image_mask_to_pixel_mask(self):
+        image_mask = np.asarray([[1.0, 0.0, 0.0],
+                                 [0.0, 1.0, 0.0],
+                                 [0.0, 0.0, 1.0]])
+
+        pS = self.create_basic_plane_segmentation()
+
+        pixel_mask = pS.image_to_pixel(image_mask)
+        np.testing.assert_allclose(pixel_mask, np.asarray([[0, 0, 1.0], [1, 1, 1.0], [2, 2, 1.0]]))
+
     def test_init_image_mask(self):
         w, h = 5, 5
         img_mask = [[[1.0 for x in range(w)] for y in range(h)], [[2.0 for x in range(w)] for y in range(h)]]