improc: ass2 draw border around affine transformed region in original image.

improc/ass2/affine.py

 from interpolation import pv
-from pylab import array, matrix, zeros, show
-from numpy.linalg import lstsq, inv
+from pylab import array, matrix, zeros, show, subplot, plot, figure
+from numpy.linalg import lstsq
 
 # url: http://www.leptonica.com/affine.html
 
@@ -56,5 +56,12 @@ if __name__ == '__main__':
     result = affine_transform(image, (0., half_height), (half_width, 0.),
                               (image.shape[0], half_height), 128, 128)
 
+    figure(1)
+    subplot(121)
+    x = [0, half_width, image.shape[0], half_width, 0]
+    y = [half_height, 0, half_height, image.shape[1], half_height]
+    plot(x, y, '-')
+    imshow(image, cmap='gray')
+    subplot(122)
     imshow(result, cmap='gray')
     show()