load_image - decode b64encode and encodebytes strings (#30192)

* Decode b64encode and encodebytes strings

* Remove conditional encode -- image is always a string

tests/utils/test_image_utils.py

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import codecs
 import os
 import tempfile
 import unittest
@@ -544,6 +545,23 @@ class LoadImageTester(unittest.TestCase):
 
         self.assertEqual(img_arr.shape, (64, 32, 3))
 
+    def test_load_img_base64_encoded_bytes(self):
+        try:
+            tmp_file = tempfile.mktemp()
+            with open(tmp_file, "wb") as f:
+                http_get(
+                    "https://huggingface.co/datasets/hf-internal-testing/dummy-base64-images/raw/main/image_2.txt", f
+                )
+
+            with codecs.open(tmp_file, encoding="unicode_escape") as b64:
+                img = load_image(b64.read())
+                img_arr = np.array(img)
+
+        finally:
+            os.remove(tmp_file)
+
+        self.assertEqual(img_arr.shape, (256, 256, 3))
+
     def test_load_img_rgba(self):
         # we use revision="refs/pr/1" until the PR is merged
         # https://hf.co/datasets/hf-internal-testing/fixtures_image_utils/discussions/1