Fix typo

jkseppan · jkseppan · commit 8f6706defc1d · 2015-07-08T23:16:34.000+03:00
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -1319,7 +1319,7 @@ def _writeImg(self, data, height, width, grayscale, id, smask=None):
                                         else 'DeviceRGB'),
                'BitsPerComponent': 8}
         if smask:
-            obj['Smask'] = smask
+            obj['SMask'] = smask
         if rcParams['pdf.compression']:
             png = {'Predictor': 10,
                    'Colors':    1 if grayscale else 3,
