Improved image lifecycle documentation

docs/reference/open_files.rst

@@ -47,6 +47,10 @@ Image Lifecycle
   memory. The image can now be used independently of the underlying
   image file.
 
+  Any Pillow method that creates a new image instance based on another will
+  internally call ``load()`` on the original image and then read the data.
+  The new image instance will not be associated with the original image file.
+
   If a filename or a ``Path`` object was passed to ``Image.open()``, then the
   file object was opened by Pillow and is considered to be used exclusively by
   Pillow. So if the image is a single-frame image, the file will be closed in
@@ -55,10 +59,14 @@ Image Lifecycle
   ``Image.Image.seek()`` can load the appropriate frame.
 
 * ``Image.Image.close()`` Closes the file and destroys the core image object.
-  This is used in the Pillow context manager support. e.g.::
+
+  The Pillow context manager will also close the file, but will not destroy
+  the core image object. e.g.::
 
       with Image.open('test.jpg') as img:
-         ...  # image operations here.
+         img.load()
+      assert img.fp is None
+      img.save('test.png')
 
 
 The lifecycle of a single-frame image is relatively simple. The file must