From 7a0b54881390e0d14d4f6abe5fbb531bee1fd6ad Mon Sep 17 00:00:00 2001
From: kavyalavti <kavyalavti@iitgn.ac.in>
Date: Sat, 14 Nov 2026 19:32:28 +0530
Subject: [PATCH] Fix image_to_url crash on non-ndarray array-like images

image_to_url only passed numpy.ndarray instances to write_png. Other
array-like inputs, such as nested lists, fell through to the JSON branch
and crashed with AttributeError. Send every non-string image to
write_png, which already accepts list-like data.

Fixes #2343

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 folium/utilities.py     |  2 +-
 tests/test_utilities.py | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/folium/utilities.py b/folium/utilities.py
index e9807ad91d..29454de49c 100644
--- a/folium/utilities.py
+++ b/folium/utilities.py
@@ -195,7 +195,7 @@ def image_to_url(
             img = f.read()
         b64encoded = base64.b64encode(img).decode("utf-8")
         url = f"data:image/{fileformat};base64,{b64encoded}"
-    elif "ndarray" in image.__class__.__name__:
+    elif not isinstance(image, str):
         img = write_png(image, origin=origin, colormap=colormap)
         b64encoded = base64.b64encode(img).decode("utf-8")
         url = f"data:image/png;base64,{b64encoded}"
diff --git a/tests/test_utilities.py b/tests/test_utilities.py
index 26d346ca39..21b99adc40 100644
--- a/tests/test_utilities.py
+++ b/tests/test_utilities.py
@@ -11,6 +11,7 @@
     escape_double_quotes,
     get_obj_in_upper_tree,
     if_pandas_df_convert_to_numpy,
+    image_to_url,
     javascript_identifier_path_to_array_notation,
     normalize_bounds_type,
     parse_font_size,
@@ -234,6 +235,25 @@ def test_is_url(url):
     assert _is_url(url) is True
 
 
+@pytest.mark.parametrize(
+    "image",
+    [
+        [[0.0, 1.0], [1.0, 0.0]],
+        [[[255, 0, 0], [0, 255, 0]], [[0, 0, 255], [255, 255, 255]]],
+        ((0.0, 1.0), (1.0, 0.0)),
+    ],
+)
+def test_image_to_url_array_like(image):
+    url = image_to_url(image)
+    assert url == image_to_url(np.array(image))
+    assert url.startswith("data:image/png;base64,")
+
+
+def test_image_to_url_url():
+    url = "https://example.com/img.png"
+    assert image_to_url(url) == url
+
+
 @pytest.mark.parametrize(
     "text,result",
     [