scverse · timtreis · Aug 7, 2026 · Aug 6, 2026 · Aug 6, 2026 · Aug 6, 2026
diff --git a/src/spatialdata_plot/pl/render.py b/src/spatialdata_plot/pl/render.py
@@ -1067,6 +1067,11 @@ def _scatter_points(
         x,
         y,
         s=size,
+        # No edge stroke: matplotlib's default (edgecolors="face", linewidths=1pt) strokes each
+        # circle marker with a fixed points-unit ring. When the fill disk goes sub-pixel (tiny
+        # `size` at high dpi) only that ring survives, rendering markers as hollow outlines.
+        # linewidths=0 keeps them solid fills whose radius honours `size`.
+        linewidths=0,
         rasterized=sc_settings._vector_friendly,
         alpha=alpha,
         transform=trans_data,

diff --git a/tests/_images/Points_can_annotate_points_with_nan_in_df_categorical.png b/tests/_images/Points_can_annotate_points_with_nan_in_df_categorical.png
diff --git a/tests/_images/Points_can_annotate_points_with_nan_in_df_continuous.png b/tests/_images/Points_can_annotate_points_with_nan_in_df_continuous.png
diff --git a/tests/_images/Points_can_annotate_points_with_nan_in_table_X_continuous.png b/tests/_images/Points_can_annotate_points_with_nan_in_table_X_continuous.png
diff --git a/...ges/Points_can_annotate_points_with_nan_in_table_obs_categorical_matplotlib.png b/...ges/Points_can_annotate_points_with_nan_in_table_obs_categorical_matplotlib.png
diff --git a/tests/_images/Points_can_annotate_points_with_nan_in_table_obs_continuous.png b/tests/_images/Points_can_annotate_points_with_nan_in_table_obs_continuous.png
diff --git a/tests/_images/Points_can_annotate_points_with_table_obs.png b/tests/_images/Points_can_annotate_points_with_table_obs.png
diff --git a/tests/_images/Points_can_filter_with_groups_custom_palette.png b/tests/_images/Points_can_filter_with_groups_custom_palette.png
diff --git a/tests/_images/Points_can_filter_with_groups_default_palette.png b/tests/_images/Points_can_filter_with_groups_default_palette.png
diff --git a/tests/_images/Points_can_stack_render_points.png b/tests/_images/Points_can_stack_render_points.png
diff --git a/tests/_images/Points_can_use_norm_with_clip.png b/tests/_images/Points_can_use_norm_with_clip.png
diff --git a/tests/_images/Points_can_use_norm_without_clip.png b/tests/_images/Points_can_use_norm_without_clip.png
diff --git a/tests/_images/Points_datashader_matplotlib_stack.png b/tests/_images/Points_datashader_matplotlib_stack.png
diff --git a/tests/_images/Points_groups_na_color_none_filters_points.png b/tests/_images/Points_groups_na_color_none_filters_points.png
diff --git a/tests/_images/Points_points_render_permutations.png b/tests/_images/Points_points_render_permutations.png
diff --git a/tests/pl/test_render_points.py b/tests/pl/test_render_points.py
@@ -3,6 +3,7 @@
 import dask.dataframe
 import datashader as ds
 import matplotlib
+import matplotlib.collections
 import matplotlib.pyplot as plt
 import numpy as np
 import pandas as pd
@@ -253,6 +254,22 @@ def test_render_points_missing_region_for_table_raises_key_error(self, sdata_blo
         with pytest.raises(KeyError, match="does not annotate element"):
             blob.pl.render_points(element="blobs_points", color="table_value", table_name="other_table")
 
+    def test_render_points_markers_have_no_edge_stroke(self, sdata_blobs: SpatialData) -> None:
+        # Regression test for #756: matplotlib's default scatter edge stroke (linewidths=1pt) turns
+        # small markers at high dpi into hollow "outlined" circles. The scatter collection must carry
+        # a zero linewidth so markers stay solid fills at every size.
+        # This is a fast, non-visual guard on the mechanism; the pixel-level "solid disk" appearance
+        # (whose only tell is a subtle annular minimum, awkward to assert without flakiness) is covered
+        # by the CI image-comparison baselines. A literal colour avoids the categorical legend's own
+        # (linewidth-1) scatter handles.
+        sdata_blobs.pl.render_points("blobs_points", color="red", size=0.1, method="matplotlib").pl.show(dpi=300)
+        ax = plt.gca()
+        collections = [c for c in ax.collections if isinstance(c, matplotlib.collections.PathCollection)]
+        assert collections, "no scatter collection was drawn"
+        for coll in collections:
+            assert np.all(coll.get_linewidths() == 0)
+        plt.close()
+
     def test_plot_datashader_colors_from_table_obs(self, sdata_blobs: SpatialData):
         n_obs = len(sdata_blobs["blobs_points"])
         obs = pd.DataFrame(