def elliptical():
    """Generate a test image with random ellipses and background noise."""
    im = TestImage(shift=True, nx=1000, ny=1000)
    im.addEllipseRandom(nEllipse=100, value=5)
    im.addNoise(sigma=1)
    im.hanningFilter()
    #im.zeroPad()
    im.calcAll(min_npix=2, min_dr=1)
    im.plotMore()
    pylab.savefig('elliptical.%s' %(figformat), format='%s' %(figformat))
    # Invert from ACovF 1d without phases                                             
    im.invertAcovf1d()
    im.invertAcovf2d(useI=True)
    im.invertPsd2d(useI=True)
    im.invertFft(useI=True)
    im.showImageAndImageI()
    pylab.savefig('elliptical_invert.%s' %(figformat), format='%s' %(figformat))
    pylab.close()
    return