ImProc ass2: Finished assignment.

improc/ass2/transform.py

 from interpolation import pv
-from pylab import array, matrix, zeros, show, dot, lstsq, inv, svd, subplot, \
-        plot, figure
+from numpy import array, matrix, zeros, dot
+from numpy.linalg.linalg import lstsq, inv, svd
 
 # url: http://www.leptonica.com/affine.html
 
@@ -37,7 +37,7 @@ def affine_transform(image, p1, p2, p3, width, height):
 
     for x in xrange(width):
         for y in xrange(height):
-            orig_pos = (A * array([[x, y, 1]]).T).T.tolist()[0]
+            orig_pos = A * array([[x, y, 1]]).T
             result[x][y] = pv(image, orig_pos[0], orig_pos[1], 'linear')
 
     return result
@@ -61,7 +61,7 @@ def perspective_transform(image, p1, p2, p3, p4, width, height):
                [0, 0, 0, x4, y4, 1, -height * x4, -height * y4, -height]])
 
     # Calculate transform matrix
-    A = inv(svd(M)[2].T[:,-1].reshape(3, 3))
+    A = inv(svd(M)[2][-1].reshape(3, 3))
 
     # Construct the transformed image
     result = zeros((width, height, 4))
@@ -69,32 +69,36 @@ def perspective_transform(image, p1, p2, p3, p4, width, height):
     for x in xrange(width):
         for y in xrange(height):
             p = dot(A, array([[x], [y], [1]]))
-            result[x][y] = pv(image, p[0] / p[2], p[1] / p[2], 'linear')
+            result[x][y] = pv(image, p[1] / p[2], p[0] / p[2], 'linear')
 
     return result
 
 if __name__ == '__main__':
-    from pylab import imread, imshow
-
-    #image = imread('cameraman.png')
-    image = imread('flyeronground.png')
+    from pylab import imread, imshow, plot, subplot, show, axis
 
+    # Affine transformation
+    subplot(221)
+    image = imread('cameraman.png')
     half_width = image.shape[0] / 2
     half_height = image.shape[1] / 2
-
-    M, N = image.shape[:2]
-
-    #result = affine_transform(image, (0., half_height), (half_width, 0.),
-    #                          (image.shape[0], half_height), 128, 128)
-    result = perspective_transform(image, (149, 590), (101, 376), (301, 209),
-                                   (393, 392), 64, 64)
-
-    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, '-')
+    plot(x, y, 'r-')
+    axis([0, image.shape[0], 0, image.shape[1]])
     imshow(image, cmap='gray')
-    subplot(122)
+    subplot(222)
+    result = affine_transform(image, (0., half_height), (half_width, 0.),
+                              (image.shape[0], half_height), 128, 128)
     imshow(result, cmap='gray')
+
+    # Perspective transformation
+    subplot(223)
+    image = imread('flyeronground.png')
+    x, y = zip((147, 588), (100, 370), (300, 205), (392, 392), (147, 588))
+    plot(x, y, 'r-')
+    imshow(image)
+    subplot(224)
+    result = perspective_transform(image, (147, 588), (392, 392), (100, 370), \
+                                   (300, 205), 100, 150)
+    imshow(result)
     show()