Possible fix for issue #911

gistfile1.diff

diff --git a/frontend/tko/graphing_utils.py b/frontend/tko/graphing_utils.py
index 10a309c..39525fa 100644
--- a/frontend/tko/graphing_utils.py
+++ b/frontend/tko/graphing_utils.py
@@ -446,8 +446,8 @@ def _create_png(figure):
     canvas.draw()
     size = canvas.get_renderer().get_canvas_width_height()
     image_as_string = canvas.tostring_rgb()
-    image = PIL.Image.fromstring('RGB', size, image_as_string, 'raw', 'RGB', 0,
-                                 1)
+    image = PIL.Image.frombytes('RGB', size, image_as_string, 'raw', 'RGB', 0,
+                                1)
     image_background = PIL.Image.new(image.mode, image.size,
                                      figure.get_facecolor())