Fix: Support 'jpg' format in keras.utils.save_img() (#21683)

* Fix save_img(): support 'jpg' format and handle RGBA

* Fix save_img: support 'jpg' format (normalize to JPEG) and add tests

* Fix save_img: normalize jpg→jpeg, handle RGBA→RGB, and improve tests

* Regenerate API directory

* Add save_img to image_utils.py and integration tests for JPG/RGBA handling

* style: fix formatting with format.sh

* Simplify save_img: remove _format, normalize jpg→jpeg, add RGBA→RGB handling and tests

* Simplify save_img: remove _format, normalize jpg→jpeg, add RGBA→RGB handling and tests

* Simplify save_img: remove _format, normalize jpg→jpeg, add RGBA→RGB handling and tests

* fix: use save_format variable to avoid modifying file_format parameter

* fix: handle .jpg format without renaming file, improve tests

* Move save_img tests to unit tests and convert to Keras TestCase

* Move save_img tests to unit tests and convert to Keras TestCase

* Move save_img tests to unit tests and convert to Keras TestCase

* Move save_img tests to unit tests and convert to Keras TestCase

* fix: simplify file format handling and add inferred format test

* fix: simplify file format handling and add inferred format test

* fix: simplify file format handling and add inferred format test

Author: utsab345

keras/src/utils/image_utils.py

@@ -175,12 +175,24 @@ def save_img(path, x, data_format=None, file_format=None, scale=True, **kwargs):
         **kwargs: Additional keyword arguments passed to `PIL.Image.save()`.
     """
     data_format = backend.standardize_data_format(data_format)
+
+    # Infer format from path if not explicitly provided
+    if file_format is None and isinstance(path, (str, pathlib.Path)):
+        file_format = pathlib.Path(path).suffix[1:].lower()
+
+    # Normalize jpg → jpeg for Pillow compatibility
+    if file_format and file_format.lower() == "jpg":
+        file_format = "jpeg"
+
     img = array_to_img(x, data_format=data_format, scale=scale)
-    if img.mode == "RGBA" and (file_format == "jpg" or file_format == "jpeg"):
+
+    # Handle RGBA → RGB conversion for JPEG
+    if img.mode == "RGBA" and file_format == "jpeg":
         warnings.warn(
-            "The JPG format does not support RGBA images, converting to RGB."
+            "The JPEG format does not support RGBA images, converting to RGB."
         )
         img = img.convert("RGB")
+
     img.save(path, format=file_format, **kwargs)
 
 

keras/src/utils/image_utils_test.py

@@ -0,0 +1,36 @@
+import os
+
+import numpy as np
+from absl.testing import parameterized
+
+from keras.src import testing
+from keras.src.utils import img_to_array
+from keras.src.utils import load_img
+from keras.src.utils import save_img
+
+
+class SaveImgTest(testing.TestCase, parameterized.TestCase):
+    @parameterized.named_parameters(
+        ("rgb_explicit_format", (50, 50, 3), "rgb.jpg", "jpg", True),
+        ("rgba_explicit_format", (50, 50, 4), "rgba.jpg", "jpg", True),
+        ("rgb_inferred_format", (50, 50, 3), "rgb_inferred.jpg", None, False),
+        ("rgba_inferred_format", (50, 50, 4), "rgba_inferred.jpg", None, False),
+    )
+    def test_save_jpg(self, shape, name, file_format, use_explicit_format):
+        tmp_dir = self.get_temp_dir()
+        path = os.path.join(tmp_dir, name)
+
+        img = np.random.randint(0, 256, size=shape, dtype=np.uint8)
+
+        # Test the actual inferred case - don't pass file_format at all
+        if use_explicit_format:
+            save_img(path, img, file_format=file_format)
+        else:
+            save_img(path, img)  # Let it infer from path
+
+        self.assertTrue(os.path.exists(path))
+
+        # Verify saved image is correctly converted to RGB if needed
+        loaded_img = load_img(path)
+        loaded_array = img_to_array(loaded_img)
+        self.assertEqual(loaded_array.shape, (50, 50, 3))