Add alternate example for match_template.

doc/examples/plot_match_face_template.py

@@ -0,0 +1,41 @@
+"""
+=================
+Template Matching
+=================
+
+In this example, we use template matching to identify the occurrence of an
+image patch (in this case, a sub-image centered on the camera man's head).
+Since there's only a single match, the maximum value in the `match_template`
+result` corresponds to the head location. If you expect multiple matches, you
+should use a proper peak-finding function.
+
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+from skimage import data
+from skimage.feature import match_template
+
+image = data.camera()
+head = image[70:170, 180:280]
+
+result = match_template(image, head)
+
+fig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(8, 4))
+
+ax1.imshow(head)
+ax1.set_axis_off()
+ax1.set_title('template')
+
+ax2.imshow(image)
+ax2.set_axis_off()
+ax2.set_title('image')
+
+# highlight matched region
+xy = np.unravel_index(np.argmax(result), image.shape)[::-1] # -1 flips ij to xy
+wface, hface = head.shape
+rect = plt.Rectangle(xy, wface, hface, edgecolor='r', facecolor='none')
+ax2.add_patch(rect)
+
+plt.show()
+