Skip None entries in png metadata.

anntzer · anntzer · commit 92a33aa7d85a · 2020-05-29T13:07:50.000+02:00
diff --git a/lib/matplotlib/backends/backend_agg.py b/lib/matplotlib/backends/backend_agg.py
@@ -484,8 +484,8 @@ def print_png(self, filename_or_obj, *args,
 
             Other keywords may be invented for other purposes.
 
-            If 'Software' is not given, an autogenerated value for matplotlib
-            will be used.
+            If 'Software' is not given, an autogenerated value for Matplotlib
+            will be used.  This can be removed by setting it to *None*.
 
             For more details see the `PNG specification`_.
 
diff --git a/lib/matplotlib/image.py b/lib/matplotlib/image.py
@@ -1543,7 +1543,8 @@ def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,
                 }
                 pil_kwargs["pnginfo"] = pnginfo = PIL.PngImagePlugin.PngInfo()
                 for k, v in metadata.items():
-                    pnginfo.add_text(k, v)
+                    if v is not None:
+                        pnginfo.add_text(k, v)
         if format in ["jpg", "jpeg"]:
             format = "jpeg"  # Pillow doesn't recognize "jpg".
             facecolor = mpl.rcParams["savefig.facecolor"]
