Fix ImagingAccess for I;16N on big-endian

Tests/helper.py

@@ -29,6 +29,33 @@
     uploader = "github_actions"
 
 
+modes = (
+    "1",
+    "L",
+    "LA",
+    "La",
+    "P",
+    "PA",
+    "F",
+    "I",
+    "I;16",
+    "I;16L",
+    "I;16B",
+    "I;16N",
+    "RGB",
+    "RGBA",
+    "RGBa",
+    "RGBX",
+    "BGR;15",
+    "BGR;16",
+    "BGR;24",
+    "CMYK",
+    "YCbCr",
+    "HSV",
+    "LAB",
+)
+
+
 def upload(a: Image.Image, b: Image.Image) -> str | None:
     if uploader == "show":
         # local img.show for errors.

Tests/test_image.py

@@ -28,43 +28,16 @@
     assert_image_similar_tofile,
     assert_not_all_same,
     hopper,
+    is_big_endian,
     is_win32,
     mark_if_feature_version,
+    modes,
     skip_unless_feature,
 )
 
-# name, pixel size
-image_modes = (
-    ("1", 1),
-    ("L", 1),
-    ("LA", 4),
-    ("La", 4),
-    ("P", 1),
-    ("PA", 4),
-    ("F", 4),
-    ("I", 4),
-    ("I;16", 2),
-    ("I;16L", 2),
-    ("I;16B", 2),
-    ("I;16N", 2),
-    ("RGB", 4),
-    ("RGBA", 4),
-    ("RGBa", 4),
-    ("RGBX", 4),
-    ("BGR;15", 2),
-    ("BGR;16", 2),
-    ("BGR;24", 3),
-    ("CMYK", 4),
-    ("YCbCr", 4),
-    ("HSV", 4),
-    ("LAB", 4),
-)
-
-image_mode_names = [name for name, _ in image_modes]
-
 
 class TestImage:
-    @pytest.mark.parametrize("mode", image_mode_names)
+    @pytest.mark.parametrize("mode", modes)
     def test_image_modes_success(self, mode: str) -> None:
         Image.new(mode, (1, 1))
 
@@ -1045,15 +1018,15 @@ def test_close_graceful(self, caplog: pytest.LogCaptureFixture) -> None:
 
 
 class TestImageBytes:
-    @pytest.mark.parametrize("mode", image_mode_names)
+    @pytest.mark.parametrize("mode", modes)
     def test_roundtrip_bytes_constructor(self, mode: str) -> None:
         im = hopper(mode)
         source_bytes = im.tobytes()
 
         reloaded = Image.frombytes(mode, im.size, source_bytes)
         assert reloaded.tobytes() == source_bytes
 
-    @pytest.mark.parametrize("mode", image_mode_names)
+    @pytest.mark.parametrize("mode", modes)
     def test_roundtrip_bytes_method(self, mode: str) -> None:
         im = hopper(mode)
         source_bytes = im.tobytes()
@@ -1062,12 +1035,11 @@ def test_roundtrip_bytes_method(self, mode: str) -> None:
         reloaded.frombytes(source_bytes)
         assert reloaded.tobytes() == source_bytes
 
-    @pytest.mark.parametrize(("mode", "pixelsize"), image_modes)
-    def test_getdata_putdata(self, mode: str, pixelsize: int) -> None:
-        im = Image.new(mode, (2, 2))
-        source_bytes = bytes(range(im.width * im.height * pixelsize))
-        im.frombytes(source_bytes)
-
+    @pytest.mark.parametrize("mode", modes)
+    def test_getdata_putdata(self, mode: str) -> None:
+        if is_big_endian and mode == "BGR;15":
+            pytest.xfail("Known failure of BGR;15 on big-endian")
+        im = hopper(mode)
         reloaded = Image.new(mode, im.size)
         reloaded.putdata(im.getdata())
         assert_image_equal(im, reloaded)

Tests/test_image_access.py

@@ -10,7 +10,7 @@
 
 from PIL import Image
 
-from .helper import assert_image_equal, hopper, is_win32
+from .helper import assert_image_equal, hopper, is_win32, modes
 
 # CFFI imports pycparser which doesn't support PYTHONOPTIMIZE=2
 # https://github.com/eliben/pycparser/pull/198#issuecomment-317001670
@@ -138,8 +138,8 @@ def color(mode: str) -> int | tuple[int, ...]:
         if bands == 1:
             return 1
         if mode in ("BGR;15", "BGR;16"):
-            # These modes have less than 8 bits per band
-            # So (1, 2, 3) cannot be roundtripped
+            # These modes have less than 8 bits per band,
+            # so (1, 2, 3) cannot be roundtripped.
             return (16, 32, 49)
         return tuple(range(1, bands + 1))
 
@@ -168,16 +168,15 @@ def check(self, mode: str, expected_color_int: int | None = None) -> None:
             f"expected {expected_color} got {actual_color}"
         )
 
-        # Check 0
+        # check 0x0 image with None initial color
         im = Image.new(mode, (0, 0), None)
         assert im.load() is not None
-
         error = ValueError if self._need_cffi_access else IndexError
         with pytest.raises(error):
             im.putpixel((0, 0), expected_color)
         with pytest.raises(error):
             im.getpixel((0, 0))
-        # Check 0 negative index
+        # check negative index
         with pytest.raises(error):
             im.putpixel((-1, -1), expected_color)
         with pytest.raises(error):
@@ -198,36 +197,15 @@ def check(self, mode: str, expected_color_int: int | None = None) -> None:
             f"expected {expected_color} got {actual_color}"
         )
 
-        # Check 0
+        # check 0x0 image with initial color
         im = Image.new(mode, (0, 0), expected_color)
         with pytest.raises(error):
             im.getpixel((0, 0))
-        # Check 0 negative index
+        # check negative index
         with pytest.raises(error):
             im.getpixel((-1, -1))
 
-    @pytest.mark.parametrize(
-        "mode",
-        (
-            "1",
-            "L",
-            "LA",
-            "I",
-            "I;16",
-            "I;16B",
-            "F",
-            "P",
-            "PA",
-            "BGR;15",
-            "BGR;16",
-            "BGR;24",
-            "RGB",
-            "RGBA",
-            "RGBX",
-            "CMYK",
-            "YCbCr",
-        ),
-    )
+    @pytest.mark.parametrize("mode", modes)
     def test_basic(self, mode: str) -> None:
         self.check(mode)
 

Tests/test_lib_pack.py

@@ -216,7 +216,10 @@ def test_I(self) -> None:
             )
 
     def test_I16(self) -> None:
-        self.assert_pack("I;16N", "I;16N", 2, 0x0201, 0x0403, 0x0605)
+        if sys.byteorder == "little":
+            self.assert_pack("I;16N", "I;16N", 2, 0x0201, 0x0403, 0x0605)
+        else:
+            self.assert_pack("I;16N", "I;16N", 2, 0x0102, 0x0304, 0x0506)
 
     def test_F_float(self) -> None:
         self.assert_pack("F", "F;32F", 4, 1.539989614439558e-36, 4.063216068939723e-34)

src/libImaging/Access.c

@@ -81,12 +81,6 @@ get_pixel_16B(Imaging im, int x, int y, void *color) {
 #endif
 }
 
-static void
-get_pixel_16(Imaging im, int x, int y, void *color) {
-    UINT8 *in = (UINT8 *)&im->image[y][x + x];
-    memcpy(color, in, sizeof(UINT16));
-}
-
 static void
 get_pixel_BGR15(Imaging im, int x, int y, void *color) {
     UINT8 *in = (UINT8 *)&im->image8[y][x * 2];
@@ -207,7 +201,11 @@ ImagingAccessInit() {
     ADD("I;16", get_pixel_16L, put_pixel_16L);
     ADD("I;16L", get_pixel_16L, put_pixel_16L);
     ADD("I;16B", get_pixel_16B, put_pixel_16B);
-    ADD("I;16N", get_pixel_16, put_pixel_16L);
+#ifdef WORDS_BIGENDIAN
+    ADD("I;16N", get_pixel_16B, put_pixel_16B);
+#else
+    ADD("I;16N", get_pixel_16L, put_pixel_16L);
+#endif
     ADD("I;32L", get_pixel_32L, put_pixel_32L);
     ADD("I;32B", get_pixel_32B, put_pixel_32B);
     ADD("F", get_pixel_32, put_pixel_32);