Do not resize macOS retina screenshots by default

Tests/test_imagegrab.py

@@ -25,8 +25,15 @@ def test_grab(self) -> None:
         ImageGrab.grab(include_layered_windows=True)
         ImageGrab.grab(all_screens=True)
 
-        im = ImageGrab.grab(bbox=(10, 20, 50, 80))
-        assert im.size == (40, 60)
+        if sys.platform == "darwin":
+            im = ImageGrab.grab(bbox=(10, 20, 50, 80))
+            assert im.size in ((40, 60), (80, 120))
+
+            im = ImageGrab.grab(bbox=(10, 20, 50, 80), scale_down=True)
+            assert im.size == (40, 60)
+        else:
+            im = ImageGrab.grab(bbox=(10, 20, 50, 80))
+            assert im.size == (40, 60)
 
     @skip_unless_feature("xcb")
     def test_grab_x11(self) -> None:

docs/reference/ImageGrab.rst

@@ -9,11 +9,14 @@ or the clipboard to a PIL image memory.
 
 .. versionadded:: 1.1.3
 
-.. py:function:: grab(bbox=None, include_layered_windows=False, all_screens=False, xdisplay=None, window=None)
+.. py:function:: grab(bbox=None, include_layered_windows=False, all_screens=False, xdisplay=None, window=None, scale_down=False)
 
     Take a snapshot of the screen. The pixels inside the bounding box are returned as
-    an "RGBA" on macOS, or an "RGB" image otherwise. If the bounding box is omitted,
-    the entire screen is copied, and on macOS, it will be at 2x if on a Retina screen.
+    "RGBA" on macOS, or "RGB" image otherwise. If the bounding box is omitted,
+    the entire screen is copied.
+
+    On macOS, it will be at 2x if on a Retina screen. If this is not desired, pass
+    ``scale_down=True``.
 
     On Linux, if ``xdisplay`` is ``None`` and the default X11 display does not return
     a snapshot of the screen, ``gnome-screenshot``, ``grim`` or ``spectacle`` will be
@@ -25,8 +28,8 @@ or the clipboard to a PIL image memory.
     .. versionadded:: 7.1.0 Linux support
 
     :param bbox: What region to copy. Default is the entire screen.
-                 On macOS, this is not increased to 2x for Retina screens, so the full
-                 width of a Retina screen would be 1440, not 2880.
+                 On macOS, this is increased to 2x for Retina screens, so the full
+                 width of a Retina screen would be 2880, not 1440.
                  On Windows, the top-left point may be negative if ``all_screens=True``
                  is used.
     :param include_layered_windows: Includes layered windows. Windows OS only.
@@ -47,6 +50,11 @@ or the clipboard to a PIL image memory.
         HWND, to capture a single window. Windows only.
 
         .. versionadded:: 11.2.1
+
+    :param scale_down: On macOS, Retina screens will provide images at 2x size by default. This will prevent that, and scale down to 1x.
+                       Keyword-only argument.
+
+        .. versionadded:: 12.1.0
     :return: An image
 
 .. py:function:: grabclipboard()

src/PIL/ImageGrab.py

@@ -36,6 +36,8 @@ def grab(
     all_screens: bool = False,
     xdisplay: str | None = None,
     window: int | ImageWin.HWND | None = None,
+    *,
+    scale_down: bool = False,
 ) -> Image.Image:
     im: Image.Image
     if xdisplay is None:
@@ -50,7 +52,7 @@ def grab(
             im = Image.open(filepath)
             im.load()
             os.unlink(filepath)
-            if bbox:
+            if bbox and scale_down:
                 im_resized = im.resize((right - left, bottom - top))
                 im.close()
                 return im_resized