remove null values from saved preporcessor file for fast image processor

Author: yonigozlan

src/transformers/image_processing_utils_fast.py

@@ -936,6 +936,10 @@ def _preprocess(
 
     def to_dict(self):
         encoder_dict = super().to_dict()
+
+        # Remove attributes with None values (potentially inherited from the base class but not used)
+        encoder_dict = {k: v for k, v in encoder_dict.items() if v is not None}
+
         encoder_dict.pop("_valid_processor_keys", None)
         encoder_dict.pop("_valid_kwargs_names", None)
         return encoder_dict

tests/test_image_processing_common.py

@@ -341,9 +341,10 @@ def test_save_load_fast_slow(self):
         }
         dict_fast_0 = {key: dict_fast_0[key] for key in set(dict_fast_0) & set(dict_fast_1)}
         dict_fast_1 = {key: dict_fast_1[key] for key in set(dict_fast_0) & set(dict_fast_1)}
-        # check that all additional keys are None, except for `default_to_square` and `data_format` which are only set in fast processors
+        # Fast processors filter None values from to_dict(), so differences should only be special keys
         self.assertTrue(
-            all(value is None for key, value in difference.items() if key not in ["default_to_square", "data_format"])
+            all(key in ["default_to_square", "data_format"] for key in difference.keys()),
+            f"Fast processors should only differ in special keys, found: {list(difference.keys())}",
         )
         # check that the remaining keys are the same
         self.assertEqual(dict_fast_0, dict_fast_1)
@@ -391,9 +392,10 @@ def test_save_load_fast_slow_auto(self):
         }
         dict_fast_0 = {key: dict_fast_0[key] for key in set(dict_fast_0) & set(dict_fast_1)}
         dict_fast_1 = {key: dict_fast_1[key] for key in set(dict_fast_0) & set(dict_fast_1)}
-        # check that all additional keys are None, except for `default_to_square` and `data_format` which are only set in fast processors
+        # Fast processors filter None values from to_dict(), so differences should only be special keys
         self.assertTrue(
-            all(value is None for key, value in difference.items() if key not in ["default_to_square", "data_format"])
+            all(key in ["default_to_square", "data_format"] for key in difference.keys()),
+            f"Fast processors should only differ in special keys, found: {list(difference.keys())}",
         )
         # check that the remaining keys are the same
         self.assertEqual(dict_fast_0, dict_fast_1)
@@ -693,6 +695,17 @@ def _is_old_model_by_commit_date(model_type, date_cutoff=(2025, 9, 1)):
             f"a fast image processor implementation. Please implement the corresponding fast processor.",
         )
 
+    def test_fast_image_processor_to_dict_no_none_values(self):
+        """Test that fast image processors don't include None values in to_dict() output."""
+        if self.fast_image_processing_class is None:
+            self.skipTest("Skipping test as fast image processor is not defined")
+
+        image_processor = self.fast_image_processing_class(**self.image_processor_dict)
+        processor_dict = image_processor.to_dict()
+
+        none_values = [k for k, v in processor_dict.items() if v is None]
+        self.assertEqual(len(none_values), 0, f"Found None values in to_dict(): {none_values}")
+
 
 class AnnotationFormatTestMixin:
     # this mixin adds a test to assert that usages of the