Deprecate IM image format

Tests/test_file_im.py

@@ -15,24 +15,28 @@
 
 
 def test_sanity() -> None:
-    with Image.open(TEST_IM) as im:
-        im.load()
-        assert im.mode == "RGB"
-        assert im.size == (128, 128)
-        assert im.format == "IM"
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        im = Image.open(TEST_IM)
+    im.load()
+    assert im.mode == "RGB"
+    assert im.size == (128, 128)
+    assert im.format == "IM"
+    im.close()
 
 
 def test_name_limit(tmp_path: Path) -> None:
     out = tmp_path / ("name_limit_test" * 7 + ".im")
-    with Image.open(TEST_IM) as im:
-        im.save(out)
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        with Image.open(TEST_IM) as im:
+            im.save(out)
     assert filecmp.cmp(out, "Tests/images/hopper_long_name.im")
 
 
 @pytest.mark.skipif(is_pypy(), reason="Requires CPython")
 def test_unclosed_file() -> None:
     def open_test_image() -> None:
-        im = Image.open(TEST_IM)
+        with pytest.warns(DeprecationWarning, match="IM image format"):
+            im = Image.open(TEST_IM)
         im.load()
 
     with pytest.warns(ResourceWarning):
@@ -41,54 +45,63 @@ def open_test_image() -> None:
 
 def test_closed_file() -> None:
     with warnings.catch_warnings(action="error"):
-        im = Image.open(TEST_IM)
+        with pytest.warns(DeprecationWarning, match="IM image format"):
+            im = Image.open(TEST_IM)
         im.load()
         im.close()
 
 
 def test_context_manager() -> None:
     with warnings.catch_warnings(action="error"):
-        with Image.open(TEST_IM) as im:
-            im.load()
+        with pytest.warns(DeprecationWarning, match="IM image format"):
+            with Image.open(TEST_IM) as im:
+                im.load()
 
 
 def test_tell() -> None:
     # Arrange
-    with Image.open(TEST_IM) as im:
-        # Act
-        frame = im.tell()
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        with Image.open(TEST_IM) as im:
+            # Act
+            frame = im.tell()
 
     # Assert
     assert frame == 0
 
 
 def test_n_frames() -> None:
-    with Image.open(TEST_IM) as im:
-        assert isinstance(im, ImImagePlugin.ImImageFile)
-        assert im.n_frames == 1
-        assert not im.is_animated
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        im = Image.open(TEST_IM)
+    assert isinstance(im, ImImagePlugin.ImImageFile)
+    assert im.n_frames == 1
+    assert not im.is_animated
+    im.close()
 
 
 def test_eoferror() -> None:
-    with Image.open(TEST_IM) as im:
-        assert isinstance(im, ImImagePlugin.ImImageFile)
-        n_frames = im.n_frames
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        im = Image.open(TEST_IM)
+    assert isinstance(im, ImImagePlugin.ImImageFile)
+    n_frames = im.n_frames
 
-        # Test seeking past the last frame
-        with pytest.raises(EOFError):
-            im.seek(n_frames)
-        assert im.tell() < n_frames
+    # Test seeking past the last frame
+    with pytest.raises(EOFError):
+        im.seek(n_frames)
+    assert im.tell() < n_frames
 
-        # Test that seeking to the last frame does not raise an error
-        im.seek(n_frames - 1)
+    # Test that seeking to the last frame does not raise an error
+    im.seek(n_frames - 1)
+    im.close()
 
 
 @pytest.mark.parametrize("mode", ("RGB", "P", "PA"))
 def test_roundtrip(mode: str, tmp_path: Path) -> None:
     out = tmp_path / "temp.im"
     im = hopper(mode)
-    im.save(out)
-    assert_image_equal_tofile(im, out)
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        im.save(out)
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        assert_image_equal_tofile(im, out)
 
 
 def test_small_palette(tmp_path: Path) -> None:
@@ -97,17 +110,21 @@ def test_small_palette(tmp_path: Path) -> None:
     im.putpalette(colors)
 
     out = tmp_path / "temp.im"
-    im.save(out)
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        im.save(out)
 
-    with Image.open(out) as reloaded:
-        assert reloaded.getpalette() == colors + [0] * 765
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        reloaded = Image.open(out)
+    assert reloaded.getpalette() == colors + [0] * 765
+    reloaded.close()
 
 
 def test_save_unsupported_mode(tmp_path: Path) -> None:
     out = tmp_path / "temp.im"
     im = hopper("HSV")
     with pytest.raises(ValueError):
-        im.save(out)
+        with pytest.warns(DeprecationWarning, match="IM image format"):
+            im.save(out)
 
 
 def test_invalid_file() -> None:
@@ -118,4 +135,5 @@ def test_invalid_file() -> None:
 
 
 def test_number() -> None:
-    assert ImImagePlugin.number("1.2") == 1.2
+    with pytest.warns(DeprecationWarning, match="IM image format"):
+        assert ImImagePlugin.number("1.2") == 1.2

Tests/test_imagefile.py

@@ -52,7 +52,8 @@ def roundtrip(format: str) -> tuple[Image.Image, Image.Image]:
         assert_image_equal(*roundtrip("BMP"))
         im1, im2 = roundtrip("GIF")
         assert_image_similar(im1.convert("P"), im2, 1)
-        assert_image_equal(*roundtrip("IM"))
+        with pytest.warns(DeprecationWarning, match="IM image format"):
+            assert_image_equal(*roundtrip("IM"))
         assert_image_equal(*roundtrip("MSP"))
         if features.check("zlib"):
             # force multiple blocks in PNG driver

Tests/test_mode_i16.py

@@ -44,7 +44,7 @@ def test_basic(tmp_path: Path, mode: str) -> None:
     im_out = im_in.transform((w, h), Image.Transform.EXTENT, (0, 0, w, h))
     verify(im_out)  # transform
 
-    filename = tmp_path / "temp.im"
+    filename = tmp_path / "temp.tiff"
     im_in.save(filename)
 
     with Image.open(filename) as im_out:

docs/deprecations.rst

@@ -21,7 +21,7 @@ ExifTags.IFD.Makernote
 ``ExifTags.IFD.MakerNote``.
 
 Image getdata()
-~~~~~~~~~~~~~~~
+^^^^^^^^^^^^^^^
 
 .. deprecated:: 12.1.0
 
@@ -30,6 +30,13 @@ Image getdata()
 identical, except that it returns a tuple of pixel values, instead of an internal
 Pillow data type.
 
+IM image format
+^^^^^^^^^^^^^^^
+
+.. deprecated:: 13.0.0
+
+The IM image format has been deprecated.
+
 Removed features
 ----------------
 

docs/handbook/image-file-formats.rst

@@ -473,6 +473,8 @@ The :py:meth:`~PIL.Image.Image.save` method can take the following keyword argum
 IM
 ^^
 
+.. deprecated:: 13.0.0
+
 IM is a format used by LabEye and other applications based on the IFUNC image
 processing library. The library reads and writes most uncompressed interchange
 versions of this format.

docs/releasenotes/13.0.0.rst

@@ -69,10 +69,13 @@ ImageCms.ImageCmsProfile.product_name and .product_info
 Deprecations
 ============
 
-TODO
-^^^^
+IM image format
+^^^^^^^^^^^^^^^
 
-TODO
+.. deprecated:: 13.0.0
+
+The IM image format has been deprecated. If you are using this format and would like
+to continue doing so, please provide a report about what other software uses it.
 
 API changes
 ===========

src/PIL/ImImagePlugin.py

@@ -31,6 +31,7 @@
 from typing import IO, Any
 
 from . import Image, ImageFile, ImagePalette
+from ._deprecate import deprecate
 from ._util import DeferredError
 
 # --------------------------------------------------------------------
@@ -106,6 +107,7 @@
 
 
 def number(s: Any) -> float:
+    deprecate("IM image format", 15)
     try:
         return int(s)
     except ValueError:
@@ -206,6 +208,8 @@ def _open(self) -> None:
             msg = "Not an IM file"
             raise SyntaxError(msg)
 
+        deprecate("IM image format", 15)
+
         # Basic attributes
         self._size = self.info[SIZE]
         self._mode = self.info[MODE]
@@ -341,6 +345,7 @@ def tell(self) -> int:
 
 
 def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
+    deprecate("IM image format", 15)
     try:
         image_type, rawmode = SAVE[im.mode]
     except KeyError as e:

src/PIL/_deprecate.py

@@ -48,6 +48,8 @@ def deprecate(
         raise RuntimeError(msg)
     elif when == 14:
         removed = "Pillow 14 (2027-10-15)"
+    elif when == 15:
+        removed = "Pillow 15 (2028-10-15)"
     else:
         msg = f"Unknown removal version: {when}. Update {__name__}?"
         raise ValueError(msg)