Merge pull request #4826 from kemaleren/seg_mask_off_by_one

fix off-by-one errors parsing stuff and thing instances

fiftyone/core/labels.py

@@ -1855,7 +1855,7 @@ def _parse_stuff_instance(mask, offset=None, frame_size=None):
     h = (ymax - ymin + 1) / height
 
     bbox = [x, y, w, h]
-    instance_mask = mask[ymin:ymax, xmin:xmax]
+    instance_mask = mask[ymin : (ymax + 1), xmin : (xmax + 1)]
 
     return bbox, instance_mask
 
@@ -1873,23 +1873,23 @@ def _parse_thing_instances(mask, offset=None, frame_size=None):
 
     labeled = skm.label(mask)
     objects = _find_slices(labeled)
-
     instances = []
-    for idx, (yslice, xslice) in objects.items():
+    for target, slc in objects.items():
+        yslice, xslice = slc
         xmin = xslice.start
-        xmax = xslice.stop
         ymin = yslice.start
-        ymax = yslice.stop
-
-        x = (xmin + x_offset) / width
-        y = (ymin + y_offset) / height
-        w = (xmax - xmin) / width
-        h = (ymax - ymin) / height
-
-        bbox = [x, y, w, h]
-        instance_mask = mask[ymin:ymax, xmin:xmax]
+        instance_offset = (
+            offset[0] + xmin,
+            offset[1] + ymin,
+        )
 
-        instances.append((bbox, instance_mask))
+        # use the labeled image mask so `_parse_stuff_instance()`
+        # can be re-used here
+        instance_mask = labeled[slc] == target
+        instance = _parse_stuff_instance(
+            instance_mask, instance_offset, frame_size
+        )
+        instances.append(instance)
 
     return instances
 

tests/unittests/label_tests.py

@@ -470,6 +470,38 @@ def poly_bounds(p):
                 decimal=1,
             )
 
+    @drop_datasets
+    def test_parse_stuff_instance(self):
+        mask = np.ones((3, 3), dtype=bool)
+        offset = (0, 0)
+        frame_size = (6, 6)
+        bbox, instance_mask = focl._parse_stuff_instance(
+            mask, offset, frame_size
+        )
+        self.assertEqual(bbox, [0.0, 0.0, 0.5, 0.5])
+        nptest.assert_array_equal(instance_mask, mask)
+
+    @drop_datasets
+    def test_parse_thing_instances(self):
+        # test on multiple disconnected objects with overlapping
+        # bounding boxes
+        mask = np.eye(5, dtype=bool)
+        mask[0, -1] = True
+        offset = (0, 0)
+        frame_size = (10, 10)
+        results = focl._parse_thing_instances(mask, offset, frame_size)
+        self.assertEqual(len(results), 2)
+
+        bbox, instance_mask = max(results, key=lambda x: x[1].size)
+        self.assertEqual(bbox, [0, 0, 0.5, 0.5])
+        expected_mask = np.eye(5, dtype=bool)
+        nptest.assert_array_equal(instance_mask, expected_mask)
+
+        bbox, instance_mask = min(results, key=lambda x: x[1].size)
+        self.assertEqual(bbox, [0.4, 0, 0.1, 0.1])
+        expected_mask = np.eye(1, dtype=bool)
+        nptest.assert_array_equal(instance_mask, expected_mask)
+
     @drop_datasets
     def test_transform_mask(self):
         # int to int