Add example script for image pyramids

doc/examples/plot_pyramid.py

@@ -0,0 +1,32 @@
+"""
+====================
+Build image pyramids
+====================
+
+This example shows how to build image pyramids.
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+from skimage import data
+from skimage import img_as_float
+from skimage.transform import build_gaussian_pyramid
+
+
+image = data.lena()
+rows, cols, dim = image.shape
+pyramid = tuple(build_gaussian_pyramid(image, downscale=2))
+
+display = np.zeros((rows, cols + cols / 2, 3), dtype=np.double)
+
+display[:rows, :cols, :] = pyramid[0]
+
+i_row = 0
+for p in pyramid[1:]:
+    n_rows, n_cols = p.shape[:2]
+    display[i_row:i_row + n_rows, cols:cols + n_cols] = p
+    i_row += n_rows
+
+plt.imshow(display)
+plt.show()