Added _repr_jpeg_() for IPython display_jpeg

Tests/test_file_jpeg.py

@@ -922,6 +922,19 @@ def closure(mode, *args):
             im.load()
             ImageFile.LOAD_TRUNCATED_IMAGES = False
 
+    def test_repr_jpeg(self):
+        im = hopper()
+
+        with Image.open(BytesIO(im._repr_jpeg_())) as repr_jpeg:
+            assert repr_jpeg.format == "JPEG"
+            assert_image_similar(im, repr_jpeg, 17)
+
+    def test_repr_jpeg_error(self):
+        im = hopper("F")
+
+        with pytest.raises(ValueError):
+            im._repr_jpeg_()
+
 
 @pytest.mark.skipif(not is_win32(), reason="Windows only")
 @skip_unless_feature("jpg")

docs/releasenotes/10.0.0.rst

@@ -160,6 +160,18 @@ TODO
 Other Changes
 =============
 
+Support display_jpeg() in IPython
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In addition to ``display()`` and ``display_png``, ``display_jpeg()`` can now
+also be used to display images in IPython::
+
+    from PIL import Image
+    from IPython.display import display_jpeg
+
+    im = Image.new("RGB", (100, 100), (255, 0, 0))
+    display_jpeg(im)
+
 Support reading signed 8-bit TIFF images
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

src/PIL/Image.py

@@ -633,19 +633,34 @@ def _repr_pretty_(self, p, cycle):
             )
         )
 
-    def _repr_png_(self):
-        """iPython display hook support
+    def _repr_image(self, image_format):
+        """Helper function for iPython display hook.
 
-        :returns: png version of the image as bytes
+        :param image_format: Image format.
+        :returns: image as bytes, saved into the given format.
         """
         b = io.BytesIO()
         try:
-            self.save(b, "PNG")
+            self.save(b, image_format)
         except Exception as e:
-            msg = "Could not save to PNG for display"
+            msg = f"Could not save to {image_format} for display"
             raise ValueError(msg) from e
         return b.getvalue()
 
+    def _repr_png_(self):
+        """iPython display hook support for PNG format.
+
+        :returns: PNG version of the image as bytes
+        """
+        return self._repr_image("PNG")
+
+    def _repr_jpeg_(self):
+        """iPython display hook support for JPEG format.
+
+        :returns: JPEG version of the image as bytes
+        """
+        return self._repr_image("JPEG")
+
     @property
     def __array_interface__(self):
         # numpy array interface support
@@ -1108,7 +1123,6 @@ def quantize(
            Available methods are :data:`Dither.NONE` or :data:`Dither.FLOYDSTEINBERG`
            (default).
         :returns: A new image
-
         """
 
         self.load()