Sync.

improc/ass2/affine.py

-from interpolation import in_image, pv
+from interpolation import pv
 from numpy import array, zeros
-from numpy.linalg import lstsq
+from numpy.linalg import lstsq, inv
 
 # url: http://www.leptonica.com/affine.html
 
@@ -28,7 +28,8 @@ def affine_transform(image, p1, p2, p3, width, height):
 
     # Calculate transform matrix
     p = lstsq(M, q)[0]
-    T = p.reshape(2, 3).T 
+    T = p.reshape(2, 3).T
+    T = inv(T)
 
     # Construct the transformed image
     result = zeros((width, height))
@@ -45,7 +46,16 @@ def affine_transform(image, p1, p2, p3, width, height):
             orig_pos = array([x, y, 1]).reshape(3, 1) * T
 
             #print x,y, tmp
-            #result[y][x] = 
+            print orig_pos, len(orig_pos)
+
+            # XXX Why is orig_pos in the format listed below?
+            #
+            #   |g h|
+            #   |i j|
+            #   |k l|
+            #
+
+            result[y][x] = pv(image, orig_pos[0], orig_pos[1], 'linear')
 
     return result
 
@@ -58,7 +68,7 @@ if __name__ == '__main__':
     half_height = image.shape[1] / 2
 
     M, N = image.shape
-    
+
     # TODO: validate MxN -> width x height
     result = affine_transform(image, (0., 0.), (0., half_height),
                               (half_width, half_height), M, N)