Merge pull request python-pillow#6042 from radarhere/tiff_bits

Clarify code and comments

Tests/test_file_tiff.py

@@ -91,17 +91,17 @@ def test_mac_tiff(self):
             assert_image_similar_tofile(im, "Tests/images/pil136.png", 1)
 
     @pytest.mark.parametrize(
-        "file_name,mode,w,h,offset",
+        "file_name,mode,size,offset",
         [
-            ("tiff_wrong_bits_per_sample.tiff", "RGBA", 52, 53, 160),
-            ("tiff_wrong_bits_per_sample_2.tiff", "RGB", 16, 16, 8),
+            ("tiff_wrong_bits_per_sample.tiff", "RGBA", (52, 53), 160),
+            ("tiff_wrong_bits_per_sample_2.tiff", "RGB", (16, 16), 8),
         ],
     )
-    def test_wrong_bits_per_sample(self, file_name, mode, w, h, offset):
+    def test_wrong_bits_per_sample(self, file_name, mode, size, offset):
         with Image.open("Tests/images/" + file_name) as im:
             assert im.mode == mode
-            assert im.size == (w, h)
-            assert im.tile == [("raw", (0, 0, w, h), offset, (mode, 0, 1))]
+            assert im.size == size
+            assert im.tile == [("raw", (0, 0) + size, offset, (mode, 0, 1))]
             im.load()
 
     def test_set_legacy_api(self):

src/PIL/TiffImagePlugin.py

@@ -1332,13 +1332,14 @@ def _setup(self):
         else:
             bps_count = 1
         bps_count += len(extra_tuple)
-        # Some files have only one value in bps_tuple,
-        # while should have more. Or have more values
-        # than expected. Fix it
         bps_actual_count = len(bps_tuple)
         if bps_count < bps_actual_count:
+            # If a file has more values in bps_tuple than expected,
+            # remove the excess.
             bps_tuple = bps_tuple[:bps_count]
         elif bps_count > bps_actual_count and bps_actual_count == 1:
+            # If a file has only one value in bps_tuple, when it should have more,
+            # presume it is the same number of bits for all of the samples.
             bps_tuple = bps_tuple * bps_count
 
         samplesPerPixel = self.tag_v2.get(