Fix display of overlay plugin when original image is updated

skimage/viewer/plugins/overlayplugin.py

@@ -2,7 +2,7 @@ from warnings import warn
 
 from skimage.util.dtype import dtype_range
 from .base import Plugin
-from ..utils import ClearColormap
+from ..utils import ClearColormap, update_axes_image
 
 
 __all__ = ['OverlayPlugin']
@@ -66,7 +66,8 @@ class OverlayPlugin(Plugin):
             self._overlay_plot = ax.imshow(image, cmap=self.cmap,
                                            vmin=vmin, vmax=vmax)
         else:
-            self._overlay_plot.set_array(image)
+            update_axes_image(self._overlay_plot, image)
+
         self.image_viewer.redraw()
 
     @property

skimage/viewer/utils/core.py

@@ -18,7 +18,8 @@ from ..qt import QtGui
 
 
 __all__ = ['init_qtapp', 'start_qtapp', 'RequiredAttr', 'figimage',
-           'LinearColormap', 'ClearColormap', 'FigureCanvas', 'new_plot']
+           'LinearColormap', 'ClearColormap', 'FigureCanvas', 'new_plot',
+           'update_axes_image']
 
 
 QApp = None
@@ -179,3 +180,22 @@ def figimage(image, scale=1, dpi=None, **kwargs):
     ax.set_axis_off()
     ax.imshow(image, **kwargs)
     return fig, ax
+
+
+def update_axes_image(image_axes, image):
+    """Update the image displayed by an image plot.
+
+    This sets the image plot's array and updates its shape appropriately
+
+    Parameters
+    ----------
+    image_axes : `matplotlib.image.AxesImage`
+        Image axes to update.
+    image : array
+        Image array.
+    """
+    image_axes.set_array(image)
+
+    # Adjust size if new image shape doesn't match the original
+    h, w = image.shape[:2]
+    image_axes.set_extent((0, w, h, 0))

skimage/viewer/viewers/core.py

@@ -221,13 +221,10 @@ class ImageViewer(QtGui.QMainWindow):
     @image.setter
     def image(self, image):
         self._img = image
-        self._image_plot.set_array(image)
+        utils.update_axes_image(self._image_plot, image)
 
-        # Adjust size if new image shape doesn't match the original
-        h, w = image.shape[:2]
-        # update data coordinates (otherwise pixel coordinates are off)
-        self._image_plot.set_extent((0, w, h, 0))
         # update display (otherwise image doesn't fill the canvas)
+        h, w = image.shape[:2]
         self.ax.set_xlim(0, w)
         self.ax.set_ylim(h, 0)
 

viewer_examples/plugins/collection_overlay.py

@@ -0,0 +1,21 @@
+"""
+==============================================
+``CollectionViewer`` with an ``OverlayPlugin``
+==============================================
+
+Demo of a CollectionViewer for viewing collections of images with an
+overlay plugin.
+
+"""
+from skimage import data
+
+from skimage.viewer import CollectionViewer
+from skimage.viewer.plugins.canny import CannyPlugin
+
+
+img_collection = [data.camera(), data.coins(), data.text()]
+
+viewer = CollectionViewer(img_collection)
+viewer += CannyPlugin()
+
+viewer.show()

viewer_examples/plugins/collection_plugin.py

@@ -1,7 +1,7 @@
 """
-=================
-Collection plugin
-=================
+==================================
+``CollectionViewer`` with a plugin
+==================================
 
 Demo of a CollectionViewer for viewing collections of images with the
 `autolevel` rank filter connected as a plugin.