Premultiply color-mapped images, since that is what the backends expect.

mdboom · mdboom · commit a44ed2f487e0 · 2012-01-05T15:14:51.000-05:00
diff --git a/lib/matplotlib/image.py b/lib/matplotlib/image.py
@@ -200,6 +200,8 @@ def _get_unsampled_image(self, A, image_extents, viewlim):
             else:
                 if self._rgbacache is None:
                     x = self.to_rgba(self._A, bytes=True)
+                    # premultiply the colors
+                    x[...,0:3] *= x[...,3:4] / 255.0
                     self._rgbacache = x
                 else:
                     x = self._rgbacache
