BUG: reset image when plugin is closed.

skimage/viewer/plugins/base.py

@@ -200,6 +200,7 @@ class Plugin(QtGui.QDialog):
         self.disconnect_image_events()
         self.remove_image_artists()
         self.image_viewer.plugins.remove(self)
+        self.image_viewer.reset_image()
         self.image_viewer.redraw()
         self.close()
 

skimage/viewer/viewers/core.py

@@ -76,7 +76,7 @@ class ImageViewer(QtGui.QMainWindow):
         self._image_plot = self.ax.images[0]
 
         self.original_image = image
-        self.image = image
+        self.image = image.copy()
         self.plugins = []
 
         # List of axes artists to check for removal.
@@ -141,6 +141,9 @@ class ImageViewer(QtGui.QMainWindow):
         self._image_plot.set_array(image)
         self.redraw()
 
+    def reset_image(self):
+        self.image = self.original_image.copy()
+
     def connect_event(self, event, callback):
         """Connect callback function to matplotlib event and return id."""
         cid = self.canvas.mpl_connect(event, callback)