Merge pull request #488 from sciunto/minor_docfix

ENH: Allow `hough_circle` to detect circles with centres outside the image.

doc/examples/plot_circular_hough_transform.py

@@ -56,7 +56,7 @@ radii = []
 for radius, h in zip(hough_radii, hough_res):
     # For each radius, extract two circles
     peaks = peak_local_max(h, num_peaks=2)
-    centers.extend(peaks - hough_radii.max())
+    centers.extend(peaks)
     accums.extend(h[peaks[:, 0], peaks[:, 1]])
     radii.extend([radius, radius])