def FFTPhaseCorrelation(FFTFixed, FFTMoving, delete_input=False):
'''
Returns the phase shift correlation of the FFT's of two images.
Dimensions of Fixed and Moving images must match
:param ndarray FixedImage: grayscale image
:param ndarray MovingImage: grayscale image
:returns: Correlation image of the FFT's. Light pixels indicate the phase is well aligned at that offset.
:rtype: ndimage
'''
if(not (FFTFixed.shape == FFTMoving.shape)):
# TODO, we should pad the smaller image in this case to allow the comparison to continue
raise ValueError("ImagePhaseCorrelation: Fixed and Moving image do not have same dimension")
#--------------------------------
# This is here in case this function ever needs to be revisited. Scipy is a lot faster working with in-place operations so this
# code has been obfuscated more than I like
# FFTFixed = fftpack.rfft2(FixedImage)
# FFTMoving = fftpack.rfft2(MovingImage)
# conjFFTFixed = conj(FFTFixed)
# Numerator = conjFFTFixed * FFTMoving
# Divisor = abs(conjFFTFixed * FFTMoving)
# T = Numerator / Divisor
# CorrelationImage = real(fftpack.irfft2(T))
#--------------------------------
conjFFTFixed = np.conjugate(FFTFixed)
if delete_input:
del FFTFixed
conjFFTFixed *= FFTMoving
if delete_input:
del FFTMoving
conjFFTFixed /= np.absolute(conjFFTFixed) # Numerator / Divisor
CorrelationImage = np.real(fftpack.irfft2(conjFFTFixed))
del conjFFTFixed
return CorrelationImage
def ift(psi):
"""Go from spectral space to physical space."""
return irfft2(psi, axes=(-2, -1))
def ift(psi):
"""Go from spectral space to physical space."""
return irfft2(psi, axes=(-2,-1))
