From f95e93669658d586eccaf9dc00f144a8d48c036f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Sch=C3=B6nberger?= <hannesschoenberger@gmail.com>
Date: Sun, 16 Sep 2012 15:39:25 +0200
Subject: [PATCH] Refactor corner detection example

---
 doc/examples/plot_corner.py | 38 +++++++++++++++++++++++++++++++++
 doc/examples/plot_harris.py | 42 -------------------------------------
 2 files changed, 38 insertions(+), 42 deletions(-)
 create mode 100644 doc/examples/plot_corner.py
 delete mode 100644 doc/examples/plot_harris.py

diff --git a/doc/examples/plot_corner.py b/doc/examples/plot_corner.py
new file mode 100644
index 00000000..7c9caa34
--- /dev/null
+++ b/doc/examples/plot_corner.py
@@ -0,0 +1,38 @@
+"""
+================
+Corner detection
+================
+
+Detect corner points using the Harris corner detector and determine subpixel
+position of corners.
+
+.. [1] http://en.wikipedia.org/wiki/Corner_detection
+.. [2] http://en.wikipedia.org/wiki/Interest_point_detection
+
+"""
+
+import numpy as np
+from matplotlib import pyplot as plt
+
+from skimage import data
+from skimage.feature import corner_harris, corner_subpix, peak_local_max
+from skimage.transform import warp, AffineTransform
+from skimage.draw import ellipse
+
+tform = AffineTransform(scale=(1.3, 1.1), rotation=1, shear=0.7,
+                        translation=(210, 50))
+image = warp(data.checkerboard(), tform.inverse, output_shape=(350, 350))
+rr, cc = ellipse(310, 175, 10, 100)
+image[rr, cc] = 1
+image[180:230, 10:60] = 1
+image[230:280, 60:110] = 1
+
+coords = peak_local_max(corner_harris(image), min_distance=5)
+coords_subpix = corner_subpix(image, coords, window_size=13)
+
+plt.gray()
+plt.imshow(image, interpolation='nearest')
+plt.plot(coords[:, 1], coords[:, 0], '.b', markersize=3)
+plt.plot(coords_subpix[:, 1], coords_subpix[:, 0], '+r', markersize=15)
+plt.axis((0, 350, 350, 0))
+plt.show()
diff --git a/doc/examples/plot_harris.py b/doc/examples/plot_harris.py
deleted file mode 100644
index 39c1f29e..00000000
--- a/doc/examples/plot_harris.py
+++ /dev/null
@@ -1,42 +0,0 @@
-"""
-===============================================================================
-Harris Corner detector
-===============================================================================
-
-The Harris corner filter [1]_ detects "interest points" [2]_ using edge
-detection in multiple directions.
-
-.. [1] http://en.wikipedia.org/wiki/Corner_detection
-.. [2] http://en.wikipedia.org/wiki/Interest_point_detection
-"""
-import numpy as np
-from matplotlib import pyplot as plt
-
-from skimage import data, img_as_float
-from skimage.feature import harris, peak_local_max
-
-
-def plot_harris_points(image, filtered_coords):
-    """ plots corners found in image"""
-
-    plt.imshow(image)
-    y, x = np.transpose(filtered_coords)
-    plt.plot(x, y, 'b.')
-    plt.axis('off')
-
-# display results
-plt.figure(figsize=(8, 3))
-im_lena = img_as_float(data.lena())
-im_text = img_as_float(data.text())
-
-filtered_coords = peak_local_max(harris(im_lena), min_distance=4)
-
-plt.axes([0, 0, 0.3, 0.95])
-plot_harris_points(im_lena, filtered_coords)
-
-filtered_coords = peak_local_max(harris(im_text), min_distance=4)
-
-plt.axes([0.2, 0, 0.77, 1])
-plot_harris_points(im_text, filtered_coords)
-
-plt.show()