from scipy import interpolate
from pylab import *
box = zeros((20,20))
box[5:15, 5:15] = ones((10,10))
L = shape(box)[1]
hann = hanning(L)   # 1D window
M = (L-1)/2.0
xx = linspace(-M,M,L)
x, y = meshgrid(xx, xx.T)
r = sqrt( x**2 + y**2 )
rot_hann2D = zeros((shape(box)))
f = interpolate.interp1d(xx, hann)
rot_hann2D[nonzero(r<=M)] = f(r[r<=M])

a = shape(box[0])
b = shape(box[1])
r = x**2/a + y**2/b