Added active contour model

2026-09-09 11:33:41 +08:00 · 2015-08-31 16:15:08 +01:00
parent 069c575955
commit 646c2102d2
3 changed files with 310 additions and 0 deletions
@@ -0,0 +1,109 @@
+import numpy as np
+from skimage import data
+from skimage.color import rgb2gray
+from skimage.filters import gaussian_filter, sobel
+from skimage.segmentation import active_contour_model
+from numpy.testing import assert_equal, assert_allclose, assert_raises
+
+def periodic_reference_test():
+    img = data.astronaut()
+    img = rgb2gray(img)
+    s = np.linspace(0,2*np.pi,400)
+    x = 220 + 100*np.cos(s)
+    y = 100 + 100*np.sin(s)
+    init = np.array([x, y]).T
+    snake = active_contour_model(gaussian_filter(img,3), init,
+        alpha=0.015, beta=10, w_line=0, w_edge=1, gamma=0.001)
+    refx = [299, 298, 298, 298, 298, 297, 297, 296, 296, 295]
+    refy = [98, 99, 100, 101, 102, 103, 104, 105, 106, 108]
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+
+
+def fixed_reference_test():
+    img = data.text()
+    x = np.linspace(5,424,100)
+    y = np.linspace(136,50,100)
+    init = np.array([x, y]).T
+    snake = active_contour_model(gaussian_filter(img,1), init, bc='fixed',
+            alpha=0.1, beta=1.0, w_line=-5, w_edge=0, gamma=0.1)
+    refx = [5, 9, 13, 17, 21, 25, 30, 34, 38, 42]
+    refy = [136, 135, 134, 133, 132, 131, 129, 128, 127, 125]
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+
+
+def free_reference_test():
+    img = data.text()
+    x = np.linspace(5,424,100)
+    y = np.linspace(70,40,100)
+    init = np.array([x, y]).T
+    snake = active_contour_model(gaussian_filter(img,3), init, bc='free',
+            alpha=0.1, beta=1.0, w_line=-5, w_edge=0, gamma=0.1)
+    refx = [10, 13, 16, 19, 23, 26, 29, 32, 36, 39]
+    refy = [76, 76, 75, 74, 73, 72, 71, 70, 69, 69]
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+
+
+def RGB_test():
+    img = gaussian_filter(data.text(),1)
+    imgR = np.zeros((img.shape[0],img.shape[1],3))
+    imgG = np.zeros((img.shape[0],img.shape[1],3))
+    imgRGB = np.zeros((img.shape[0],img.shape[1],3))
+    imgR[:,:,0] = img
+    imgG[:,:,1] = img
+    imgRGB[:,:,:] = img[:, :, None]
+    x = np.linspace(5,424,100)
+    y = np.linspace(136,50,100)
+    init = np.array([x, y]).T
+    snake = active_contour_model(imgR, init, bc='fixed',
+            alpha=0.1, beta=1.0, w_line=-5, w_edge=0, gamma=0.1)
+    refx = [5, 9, 13, 17, 21, 25, 30, 34, 38, 42]
+    refy = [136, 135, 134, 133, 132, 131, 129, 128, 127, 125]
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+    snake = active_contour_model(imgG, init, bc='fixed',
+            alpha=0.1, beta=1.0, w_line=-5, w_edge=0, gamma=0.1)
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+    snake = active_contour_model(imgRGB, init, bc='fixed',
+            alpha=0.1, beta=1.0, w_line=-5/3., w_edge=0, gamma=0.1)
+    assert_equal(np.array(snake[:10,0], dtype=np.int32), refx)
+    assert_equal(np.array(snake[:10,1], dtype=np.int32), refy)
+
+
+def end_points_tests():
+    img = data.astronaut()
+    img = rgb2gray(img)
+    s = np.linspace(0,2*np.pi,400)
+    x = 220 + 100*np.cos(s)
+    y = 100 + 100*np.sin(s)
+    init = np.array([x, y]).T
+    snake = active_contour_model(gaussian_filter(img,3), init,
+        bc='periodic', alpha=0.015, beta=10, w_line=0, w_edge=1, gamma=0.001,
+        max_iterations=100)
+    assert np.sum(np.abs(snake[0,:]-snake[-1,:]) ) < 2
+    snake = active_contour_model(gaussian_filter(img,3), init,
+        bc='free', alpha=0.015, beta=10, w_line=0, w_edge=1, gamma=0.001,
+        max_iterations=100)
+    assert np.sum(np.abs(snake[0,:]-snake[-1,:])) > 2
+    snake = active_contour_model(gaussian_filter(img,3), init,
+        bc='fixed', alpha=0.015, beta=10, w_line=0, w_edge=1, gamma=0.001,
+        max_iterations=100)
+    assert_allclose(snake[0,:], [x[0], y[0]], atol=1e-5)
+
+
+def bad_input_tests():
+    img = np.zeros((10, 10))
+    x = np.linspace(5, 424, 100)
+    y = np.linspace(136, 50, 100)
+    init = np.array([x, y]).T
+    np.testing.assert_raises(ValueError, active_contour_model, img, init,
+                            bc='wrong')
+    np.testing.assert_raises(ValueError, active_contour_model, img, init,
+                            max_iterations=-15)
+
+
+if __name__ == "__main__":
+    np.testing.run_module_suite()