improc ass4: various stuff

improc/ass4/canny.py

 #!/usr/bin/env python
 from matplotlib.pyplot import imread, imshow, show
-from scipy.ndimage import quiver
+from numpy import arctan
 from gauss import gD
 
 def canny(F, s):
-    pass
+    # Noise reduction by a Gauss filter
+    G = gD(F, s, 2, 2)
+
+    # Find intensity gradient
+
+    return G
+
+    # Non-maximum suppression
+
+
+    # Tracing edges
+
 
 if __name__ == '__main__':
     from sys import argv, exit
 
-    if len(argv) < 3:
-        print 'Usage: python %s' % argv[0]
+    if len(argv) < 2:
+        print 'Usage: python %s SCALE' % argv[0]
         exit(1)
 
-    s = float(argv[2])
+    s = float(argv[1])
     F = imread('cameraman.png')
     E = canny(F, s)
-    imshow(E)
+    imshow(E, cmap='gray')
     show()