def ft1D(x,y,*,axis=0,zero_DC=False):
"""Takes in x and y = y(x), and returns k and the Fourier transform
of y(x) -> f(k) along a single (1D) axis
Handles all of the annoyances of fftshift and ifftshift, and gets the
normalization right
Args:
x (np.ndarray) : independent variable, must be 1D
y (np.ndarray) : dependent variable, can be nD
Kwargs:
axis (int) : which axis to perform FFT
zero_DC (bool) : if true, sets f(0) = 0
"""
dx = x[1]-x[0]
k = fftshift(fftfreq(x.size,d=dx))*2*np.pi
fft_norm = dx
shifted_x = ifftshift(x)
if np.isclose(shifted_x[0],0):
f = fft(ifftshift(y,axes=(axis)),axis=axis)*fft_norm
else:
f = fft(y,axis=axis)*fft_norm
if zero_DC:
nd_slice = [slice(None) for i in range(len(f.shape))]
nd_slice[axis] = slice(0,1,1)
nd_slice = tuple(nd_slice)
f[nd_slice] = 0
f = fftshift(f,axes=(axis))
return k, f
def polarization_to_signal(self,P_of_t_in,*,return_polarization=False,
local_oscillator_number = -1):
"""This function generates a frequency-resolved signal from a polarization field
local_oscillator_number - usually the local oscillator will be the last pulse in the list self.efields"""
pulse_time = self.pulse_times[local_oscillator_number]
if self.gamma != 0:
exp_factor = np.exp(-self.gamma * (self.t-pulse_time))
P_of_t_in *= exp_factor
P_of_t = P_of_t_in
if return_polarization:
return P_of_t
if local_oscillator_number == 'impulsive':
efield = np.exp(1j*self.w*(pulse_time))
else:
pulse_time_ind = np.argmin(np.abs(self.t - pulse_time))
pulse_start_ind = pulse_time_ind - self.size//2
pulse_end_ind = pulse_time_ind + self.size//2 + self.size%2
t_slice = slice(pulse_start_ind, pulse_end_ind,None)
efield = np.zeros(self.t.size,dtype='complex')
efield[t_slice] = self.efields[local_oscillator_number]
efield = fftshift(ifft(ifftshift(efield)))*len(P_of_t)*(self.t[1]-self.t[0])/np.sqrt(2*np.pi)
if P_of_t.size%2:
P_of_t = P_of_t[:-1]
efield = efield[:len(P_of_t)]
P_of_w = fftshift(ifft(ifftshift(P_of_t)))*len(P_of_t)*(self.t[1]-self.t[0])/np.sqrt(2*np.pi)
signal = np.imag(P_of_w * np.conjugate(efield))
return signal
def ift1D(k,f,*,axis=0,zero_DC=False):
"""Takes in k and f = f(k), and returns x and the discrete Fourier
transform of f(k) -> y(x).
Handles all of the annoyances of fftshift and ifftshift, and gets the
normalization right
Args:
x (np.ndarray): independent variable
y (np.ndarray): dependent variable
Kwargs:
axis (int) : which axis to perform FFT
"""
dk = k[1]-k[0]
x = fftshift(fftfreq(k.size,d=dk))*2*np.pi
ifft_norm = dk*k.size/(2*np.pi)
shifted_k = ifftshift(k)
if np.isclose(shifted_k[0],0):
y = ifft(ifftshift(f,axes=(axis)),axis=axis)*ifft_norm
else:
y = ifft(f,axis=axis)*ifft_norm
if zero_DC:
nd_slice = [slice(None) for i in range(len(y.shape))]
nd_slice[axis] = slice(0,1,1)
nd_slice = tuple(nd_slice)
y[nd_slice] = 0
y = fftshift(y,axes=(axis))
return x, y
def polarization_to_signal(self,
P_of_t_in,
*,
return_polarization=False,
local_oscillator_number=-1,
undersample_factor=1):
"""This function generates a frequency-resolved signal from a polarization field
local_oscillator_number - usually the local oscillator will be the last pulse
in the list self.efields"""
undersample_slice = slice(None, None, undersample_factor)
P_of_t = P_of_t_in[undersample_slice]
t = self.t[undersample_slice]
dt = t[1] - t[0]
pulse_time = self.pulse_times[local_oscillator_number]
if self.gamma != 0:
exp_factor = np.exp(-self.gamma * np.abs(t - pulse_time))
P_of_t *= exp_factor
if self.sigma_I != 0:
inhomogeneous = np.exp(-(t - pulse_time)**2 * self.sigma_I**2 / 2)
P_of_t *= inhomogeneous
if return_polarization:
return P_of_t
pulse_time_ind = np.argmin(np.abs(self.t - pulse_time))
efield = np.zeros(self.t.size, dtype='complex')
if self.efield_t.size == 1:
# Impulsive limit
efield[pulse_time_ind] = self.efields[local_oscillator_number]
efield = fftshift(ifft(ifftshift(efield))) * efield.size / np.sqrt(
2 * np.pi)
else:
pulse_start_ind = pulse_time_ind - self.size // 2
pulse_end_ind = pulse_time_ind + self.size // 2 + self.size % 2
t_slice = slice(pulse_start_ind, pulse_end_ind, None)
efield[t_slice] = self.efields[local_oscillator_number]
efield = fftshift(ifft(ifftshift(efield))) * self.t.size * (
self.t[1] - self.t[0]) / np.sqrt(2 * np.pi)
# if P_of_t.size%2:
# P_of_t = P_of_t[:-1]
# t = t[:-1]
halfway = self.w.size // 2
pm = self.w.size // (2 * undersample_factor)
efield_min_ind = halfway - pm
efield_max_ind = halfway + pm + self.w.size % 2
efield = efield[efield_min_ind:efield_max_ind]
P_of_w = fftshift(ifft(
ifftshift(P_of_t))) * len(P_of_t) * dt / np.sqrt(2 * np.pi)
signal = np.imag(P_of_w * np.conjugate(efield))
return signal
def add_gaussian_linewidth(self, sigma):
self.old_signal = self.signal.copy()
sig_tau_t = fftshift(fft(ifftshift(self.old_signal, axes=(-1)),
axis=-1),
axes=(-1))
sig_tau_t = sig_tau_t * (
np.exp(-self.t**2 / (2 * sigma**2))[np.newaxis, np.newaxis, :] *
np.exp(-self.t21_array**2 /
(2 * sigma**2))[:, np.newaxis, np.newaxis])
sig_tau_w = fftshift(ifft(ifftshift(sig_tau_t, axes=(-1)), axis=-1),
axes=(-1))
self.signal = sig_tau_w
def stCoefs_1d(signals, filters, block_size=100, second_order=False):
"""
compute 1D signals scattering coefficents
input
signals: 2D numpy array (# samples, signal_length)
filters: 2D numpy array (# filters, signal_length)
output
filtered_signal:
3D numpy array (# samples, # filters, signal_length)
"""
signal_length = signals.shape[-1]
signal_shape = signals.shape[:-1]
signal_size = reduce(lambda x, y: x * y, signal_shape)
signals.shape = (signal_size, signal_length)
filter_length = filters.shape[-1]
filter_shape = filters.shape[:-1]
filter_size = reduce(lambda x, y: x * y, filter_shape)
filters.shape = (filter_size, filter_length)
f_signals = np.fft.fft(signals, axis=1)
f_filters = np.fft.fft(fft.ifftshift(filters, axes=(1,)), axis=1)
if not second_order:
f_conv = f_signals[:, np.newaxis, :] * f_filters[np.newaxis, :, :]
else:
f_conv = np.zeros(signal_size, filter_size, signal_length)
filtered = fft.ifft(f_conv, axis=2)
return filtered
def ft_interface(a, s, axes, norm, **kwargs):
# call fft and shift the result
shftax = axes[:-1] if omitlast else axes
if forward:
return fftmod.fftshift(ftfunc(a, s, axes, norm, **kwargs), shftax)
else:
return ftfunc(fftmod.ifftshift(a, shftax), s, axes, norm, **kwargs)
def fillPowerFromTemplate(self, twodPower):
"""
Fill the power2D.powerMap with the input power array.
Parameters
----------
twodPower : array_like
The 2D data array specifying the template power to fill with.
"""
tdp = twodPower.copy()
# interpolate
if tdp.Nx != self.Nx or tdp.Ny != self.Ny:
# first divide out the area factor
area = tdp.Nx*tdp.Ny*tdp.pixScaleX*tdp.pixScaleY
tdp.powerMap *= (tdp.Nx*tdp.Ny)**2 / area
lx_shifted = fftshift(tdp.lx)
ly_shifted = fftshift(tdp.ly)
tdp_shifted = fftshift(tdp.powerMap)
f_interp = interp2d(lx_shifted, ly_shifted, tdp_shifted)
cl_new = f_interp(fftshift(self.lx), fftshift(self.ly))
cl_new = ifftshift(cl_new)
area = self.Nx*self.Ny*self.pixScaleX*self.pixScaleY
cl_new *= area / (self.Nx*self.Ny*1.)**2
self.powerMap[:] = cl_new[:]
else:
self.powerMap[:] = tdp.powerMap[:]
def convolve(arr1, arr2, dx=None, axes=None):
"""
Performs a centred convolution of input arrays
Parameters
----------
arr1, arr2 : `numpy.ndarray`
Arrays to be convolved. If dimensions are not equal then 1s are appended
to the lower dimensional array. Otherwise, arrays must be broadcastable.
dx : float > 0, list of float, or `None` , optional
Grid spacing of input arrays. Output is scaled by
`dx**max(arr1.ndim, arr2.ndim)`. default=`None` applies no scaling
axes : tuple of ints or `None`, optional
Choice of axes to convolve. default=`None` convolves all axes
"""
if arr2.ndim > arr1.ndim:
arr1, arr2 = arr2, arr1
if axes is None:
axes = range(arr2.ndim)
arr2 = arr2.reshape(arr2.shape + (1, ) * (arr1.ndim - arr2.ndim))
if dx is None:
dx = 1
elif isscalar(dx):
dx = dx**(len(axes) if axes is not None else arr1.ndim)
else:
dx = prod(dx)
arr1 = fftn(arr1, axes=axes)
arr2 = fftn(ifftshift(arr2), axes=axes)
out = ifftn(arr1 * arr2, axes=axes) * dx
return require(out, requirements="CA")
def decomposition_fft(X, filter, **kwargs):
"""Decompose a 2d input field into multiple spatial scales by using the Fast
Fourier Transform (FFT) and a bandpass filter.
Parameters
----------
X : array_like
Two-dimensional array containing the input field. All values are required
to be finite.
filter : dict
A filter returned by any method implemented in bandpass_filters.py.
Other Parameters
----------------
MASK : array_like
Optional mask to use for computing the statistics for the cascade levels.
Pixels with MASK==False are excluded from the computations.
Returns
-------
out : ndarray
A dictionary described in the module documentation. The parameter n is
determined from the filter (see bandpass_filters.py).
"""
MASK = kwargs.get("MASK", None)
if len(X.shape) != 2:
raise ValueError("the input is not two-dimensional array")
if MASK is not None and MASK.shape != X.shape:
raise ValueError("dimension mismatch between X and MASK: X.shape=%s, MASK.shape=%s" % \
(str(X.shape), str(MASK.shape)))
if X.shape != filter["weights_2d"].shape[1:3]:
raise ValueError(
"dimension mismatch between X and filter: X.shape=%s, filter['weights_2d'].shape[1:3]=%s"
% (str(X.shape), str(filter["weights_2d"].shape[1:3])))
if np.any(~np.isfinite(X)):
raise ValueError("X contains non-finite values")
result = {}
means = []
stds = []
F = fft.fftshift(fft.fft2(X, **fft_kwargs))
X_decomp = []
for k in range(len(filter["weights_1d"])):
W_k = filter["weights_2d"][k, :, :]
X_ = np.real(fft.ifft2(fft.ifftshift(F * W_k), **fft_kwargs))
X_decomp.append(X_)
if MASK is not None:
X_ = X_[MASK]
means.append(np.mean(X_))
stds.append(np.std(X_))
result["cascade_levels"] = np.stack(X_decomp)
result["means"] = means
result["stds"] = stds
return result
def generate_psf(self,
sphase=slice(4, None, None),
size=None,
zsize=None,
zrange=None):
"""Make a perfect PSF"""
# make a copy of the internal model
model = copy.copy(self.model)
# update zsize or zrange
if zsize is not None:
model.zsize = zsize
if zrange is not None:
model.zrange = zrange
# generate the PSF from the reconstructed phase
if not hasattr(self, 'zd_result'):
self.fit_to_zernikes(120)
model._gen_psf(ifftshift(self.zd_result.complex_pupil(sphase=sphase)))
# reshpae PSF if needed in x/y dimensions
psf = model.PSFi
nz, ny, nx = psf.shape
assert ny == nx, "Something is very wrong"
if size is not None:
if nx < size:
# if size is too small, pad it out.
psf = fft_pad(psf, (nz, size, size), mode="constant")
elif nx > size:
# if size is too big, crop it
lb = size // 2
hb = size - lb
myslice = slice(nx // 2 - lb, nx // 2 + hb)
psf = psf[:, myslice, myslice]
# return data
return psf
def stCoefs_1d(signals, filters, block_size=100, second_order=False):
"""
compute 1D signals scattering coefficents
input
signals: 2D numpy array (# samples, signal_length)
filters: 2D numpy array (# filters, signal_length)
output
filtered_signal:
3D numpy array (# samples, # filters, signal_length)
"""
signal_length = signals.shape[-1]
signal_shape = signals.shape[:-1]
signal_size = reduce(lambda x, y: x * y, signal_shape)
signals.shape = (signal_size, signal_length)
filter_length = filters.shape[-1]
filter_shape = filters.shape[:-1]
filter_size = reduce(lambda x, y: x * y, filter_shape)
filters.shape = (filter_size, filter_length)
f_signals = np.fft.fft(signals, axis=1)
f_filters = np.fft.fft(fft.ifftshift(filters, axes=(1, )), axis=1)
if not second_order:
f_conv = f_signals[:, np.newaxis, :] * f_filters[np.newaxis, :, :]
else:
f_conv = np.zeros(signal_size, filter_size, signal_length)
filtered = fft.ifft(f_conv, axis=2)
return filtered
def check_efield_resolution(self, efield, *, plot_fields=False):
efield_tail = np.max(np.abs([efield[0], efield[-1]]))
if efield_tail > np.max(np.abs(efield)) / 100:
warnings.warn(
'Consider using larger time interval, pulse does not decay to less than 1% of maximum value in time domain'
)
efield_fft = fftshift(fft(ifftshift(efield))) * self.dt
efield_fft_tail = np.max(np.abs([efield_fft[0], efield_fft[-1]]))
if efield_fft_tail > np.max(np.abs(efield_fft)) / 100:
warnings.warn(
'''Consider using smaller value of dt, pulse does not decay to less than 1% of maximum value in frequency domain'''
)
if plot_fields:
fig, axes = plt.subplots(1, 2)
l1, l2, = axes[0].plot(self.efield_t, np.real(efield),
self.efield_t, np.imag(efield))
plt.legend([l1, l2], ['Real', 'Imag'])
axes[1].plot(self.efield_w, np.real(efield_fft), self.efield_w,
np.imag(efield_fft))
axes[0].set_ylabel('Electric field Amp')
axes[0].set_xlabel('Time ($\omega_0^{-1})$')
axes[1].set_xlabel('Frequency ($\omega_0$)')
fig.suptitle(
'Check that efield is well-resolved in time and frequency')
plt.show()
def retrieve_phase_far_field(src_fname,
save_path,
output_fname=None,
pad_length=256,
n_epoch=100,
learning_rate=0.001):
# raw data is assumed to be centered at zero frequency
prj_np = dxchange.read_tiff(src_fname)
if output_fname is None:
output_fname = os.path.basename(
os.path.splitext(src_fname)[0]) + '_recon'
# take modulus and inverse shift
prj_np = ifftshift(np.sqrt(prj_np))
obj_init = np.random.normal(50, 10, list(prj_np.shape) + [2])
obj = tf.Variable(obj_init, dtype=tf.float32, name='obj')
prj = tf.constant(prj_np, name='prj')
obj_real = tf.cast(obj[:, :, 0], dtype=tf.complex64)
obj_imag = tf.cast(obj[:, :, 1], dtype=tf.complex64)
# obj_pad = tf.pad(obj, [[pad_length, pad_length], [pad_length, pad_length], [0, 0]], mode='SYMMETRIC')
det = tf.fft2d(obj_real + 1j * obj_imag, name='detector_plane')
loss = tf.reduce_mean(tf.squared_difference(tf.abs(det), prj, name='loss'))
sess = tf.Session()
optimizer = tf.train.AdamOptimizer(learning_rate=learning_rate)
optimizer = optimizer.minimize(loss)
sess.run(tf.global_variables_initializer())
for i_epoch in range(n_epoch):
t0 = time.time()
_, current_loss = sess.run([optimizer, loss])
print('Iteration {}: loss = {}, Δt = {} s.'.format(
i_epoch, current_loss,
time.time() - t0))
det_final = sess.run(det)
obj_final = sess.run(obj)
res = np.linalg.norm(obj_final, 2, axis=2)
dxchange.write_tiff(res,
os.path.join(save_path, output_fname),
dtype='float32',
overwrite=True)
dxchange.write_tiff(fftshift(np.angle(det_final)),
os.path.join(save_path, 'detector_phase'),
dtype='float32',
overwrite=True)
dxchange.write_tiff(fftshift(np.abs(det_final)**2),
os.path.join(save_path, 'detector_mag'),
dtype='float32',
overwrite=True)
return
def polarization_to_signal(self,
P_of_t_in,
*,
local_oscillator_number=-1,
undersample_factor=1):
"""This function generates a frequency-resolved signal from a polarization field
local_oscillator_number - usually the local oscillator will be the last pulse
in the list self.efields"""
undersample_slice = slice(None, None, undersample_factor)
P_of_t = P_of_t_in[undersample_slice].copy()
t = self.t[undersample_slice]
dt = t[1] - t[0]
pulse_time = self.pulse_times[local_oscillator_number]
efield_t = self.efield_times[local_oscillator_number]
center = -self.centers[local_oscillator_number]
P_of_t = P_of_t # * np.exp(-1j*center*t)
pulse_time_ind = np.argmin(np.abs(self.t))
efield = np.zeros(self.t.size, dtype='complex')
if efield_t.size == 1:
# Impulsive limit: delta in time is flat in frequency
efield = np.ones(
self.w.size) * self.efields[local_oscillator_number]
else:
pulse_start_ind = pulse_time_ind - efield_t.size // 2
pulse_end_ind = pulse_time_ind + efield_t.size // 2 + efield_t.size % 2
t_slice = slice(pulse_start_ind, pulse_end_ind, None)
efield[t_slice] = self.efields[local_oscillator_number]
efield = fftshift(ifft(ifftshift(efield))) * efield.size * dt
halfway = self.w.size // 2
pm = self.w.size // (2 * undersample_factor)
efield_min_ind = halfway - pm
efield_max_ind = halfway + pm + self.w.size % 2
efield = efield[efield_min_ind:efield_max_ind]
P_of_w = fftshift(ifft(ifftshift(P_of_t))) * P_of_t.size * dt
signal = P_of_w * np.conjugate(efield)
if not self.return_complex_signal:
return np.imag(signal)
else:
return 1j * signal
def easy_ifft(data, axes=None):
"""utility method that includes fft shifting"""
return ifftshift(
ifftn(
fftshift(
data, axes=axes
), axes=axes
), axes=axes)
def cfftn(data, axes):
""" Centered fast fourier transform, n-dimensional.
:param data: Complex input data.
:param axes: Axes along which to shift and transform.
:return: Fourier transformed data.
"""
return fft.fftshift(fft.fftn(fft.ifftshift(data, axes=axes),
axes=axes,
norm='ortho'),
axes=axes)
def filter_frames(self, data):
output = np.empty_like(data[0])
nSlices = data[0].shape[self.slice_dir]
for i in range(nSlices):
self.sslice[self.slice_dir] = i
sino = fft.fftshift(self.fft_object(data[0][tuple(self.sslice)]))
sino[self.row1:self.row2] = \
sino[self.row1:self.row2] * self.filtercomplex
sino = fft.ifftshift(sino)
sino = self.ifft_object(sino).real
output[self.sslice] = sino
return output
def ft_interface(a, s, axes, norm, **kwargs):
# call fft and shift the result
if omitlast:
if isinstance(axes, int) or len(axes) < 2: # no fftshift in the case of rfft
return ftfunc(a, s, axes, norm, **kwargs)
else:
shftax = axes[:-1]
else:
shftax = axes
if forward:
return fftmod.fftshift(ftfunc(a, s, axes, norm, **kwargs), shftax)
else:
return ftfunc(fftmod.ifftshift(a, shftax), s, axes, norm, **kwargs)
def fftdeconvolve(image, psf):
"""
De-convolution by directly dividing the DFT... may not be numerically
desirable for many applications. Noise could be an issue.
Use scipy.fftpack for now; will re-write for anfft later...
Taken from this post on stackoverflow.com:
http://stackoverflow.com/questions/17473917/is-there-a-equivalent-of-scipy-signal-deconvolve-for-2d-arrays
"""
if not _pyfftw:
raise NotImplementedError
image = image.astype('float')
psf = psf.astype('float')
# image_fft = fftpack.fftshift(fftpack.fftn(image))
# psf_fft = fftpack.fftshift(fftpack.fftn(psf))
image_fft = fftshift(fftn(image))
psf_fft = fftshift(fftn(psf))
kernel = fftshift(ifftn(ifftshift(image_fft / psf_fft)))
return kernel
def fresnel_propagate(wavefield,
energy_ev,
psize_cm,
dist_cm,
fresnel_approx=True,
pad=0,
sign_convention=1):
"""
Perform Fresnel propagation on a batch of wavefields.
:param wavefield: complex wavefield with shape [n_batches, n_y, n_x].
:param energy_ev: float.
:param psize_cm: size-3 vector with pixel size ([dy, dx, dz]).
:param dist_cm: propagation distance.
:return:
"""
minibatch_size = wavefield.shape[0]
if pad > 0:
wavefield = np.pad(wavefield, [[0, 0], [pad, pad], [pad, pad]],
mode='edge')
grid_shape = wavefield.shape[1:]
if len(psize_cm) == 1: psize_cm = [psize_cm] * 3
voxel_nm = np.array(psize_cm) * 1.e7
lmbda_nm = 1240. / energy_ev
mean_voxel_nm = np.prod(voxel_nm)**(1. / 3)
size_nm = np.array(grid_shape) * voxel_nm
dist_nm = dist_cm * 1e7
h = get_kernel(dist_nm,
lmbda_nm,
voxel_nm,
grid_shape,
fresnel_approx=fresnel_approx,
sign_convention=sign_convention)
wavefield = ifft2(
ifftshift(fftshift(fft2(wavefield), axes=[1, 2]) * h, axes=[1, 2]))
if pad > 0: wavefield = wavefield[:, pad:-pad, pad:-pad]
return wavefield
def subtract_DC(signal,return_ft = False, axis = 1):
"""Use discrete fourier transform to remove the DC component of a
signal.
Args:
signal (np.ndarray): real signal to be processed
return_ft (bool): if True, return the Fourier transform of the
input signal
axis (int): axis along which the fourier trnasform is to be taken
"""
sig_fft = fft(ifftshift(signal,axes=(axis)),axis=axis)
nd_slice = [slice(None) for i in range(len(sig_fft.shape))]
nd_slice[axis] = slice(0,1,1)
nd_slice = tuple(nd_slice)
sig_fft[nd_slice] = 0
if not return_ft:
sig = fftshift(ifft(sig_fft),axes=(axis))
else:
sig = sig_fft
return sig
def fft_filter(im, rois, shift, plot=True, imshow_kwargs={}):
f0 = fft.fftshift(fft.fft2(im))
f1 = f0.copy()
if plot:
kw = dict(vmin=-0.05, vmax=1)
kw.update(imshow_kwargs)
fig, axes = plt.subplots(2,
2,
figsize=(9, 4),
sharex='col',
sharey='col')
(ax, ax_f), (ax1, ax1_f) = axes
ax.imshow(im, **kw)
ax_f.imshow(abs(f0), norm=LogNorm())
dx, dy = shift
for j, roi in enumerate(rois):
print(j, roi)
roi_t = translate_roi(roi, dx, dy)
roi_symm = symmetric_roi(roi, im.shape)
roi_symm_t = symmetric_roi(roi_t, im.shape)
f1[roi] = f1[roi_t]
f1[roi_symm] = f1[roi_symm_t]
if plot:
roi_to_rect(roi, ax=ax_f, index=j)
roi_to_rect(roi, ax=ax1_f)
roi_to_rect(roi_t, ax=ax_f, ec='r')
roi_to_rect(roi_symm, ax=ax_f)
roi_to_rect(roi_symm, ax=ax1_f)
roi_to_rect(roi_symm_t, ax=ax_f, ec='r')
im1 = fft.ifft2(fft.ifftshift(f1)).real
if plot:
ax1.imshow(im1, **kw)
ax1_f.imshow(abs(f1), norm=LogNorm())
return im1
def pattern_params(my_pat, size=2):
"""Find stuff"""
# REAL FFT!
# note the limited shifting, we don't want to shift the last axis
my_pat_fft = fftshift(rfftn(ifftshift(my_pat)),
axes=tuple(range(my_pat.ndim))[:-1])
my_abs_pat_fft = abs(my_pat_fft)
# find dc loc, center of FFT after shifting
sizeky, sizekx = my_abs_pat_fft.shape
# remember we didn't shift the last axis!
dc_loc = (sizeky // 2, 0)
# mask data and find next biggest peak
dc_power = my_abs_pat_fft[dc_loc]
my_abs_pat_fft[dc_loc] = 0
max_loc = np.unravel_index(my_abs_pat_fft.argmax(), my_abs_pat_fft.shape)
# pull the 3x3 region around the peak and fit
max_shift = localize_peak(my_abs_pat_fft[slice_maker(max_loc, 3)])
# calculate precise peak relative to dc
peak = np.array(max_loc) + np.array(max_shift) - np.array(dc_loc)
# correct location based on initial data shape
peak_corr = peak / np.array(my_pat.shape)
# calc angle
preciseangle = np.arctan2(*peak_corr)
# calc period
precise_period = 1 / norm(peak_corr)
# calc phase
phase = np.angle(my_pat_fft[max_loc[0], max_loc[1]])
# calc modulation depth
numerator = abs(my_pat_fft[slice_maker(max_loc, size)].sum())
mod = numerator / dc_power
return {"period": precise_period,
"angle": preciseangle,
"phase": phase,
"fft": my_pat_fft,
"mod": mod,
"max_loc": max_loc}
def fftconvolve_fast(data, kernel, **kwargs):
"""A faster version of fft convolution
In this case the kernel ifftshifted before FFT but the data is not.
This can be done because the effect of fourier convolution is to
"wrap" around the data edges so whether we ifftshift before FFT
and then fftshift after it makes no difference so we can skip the
step entirely.
"""
# TODO: add error checking like in the above and add functionality
# for complex inputs. Also could add options for different types of
# padding.
dshape = np.array(data.shape)
kshape = np.array(kernel.shape)
# find maximum dimensions
maxshape = np.max((dshape, kshape), 0)
# calculate a nice shape
fshape = [sig.fftpack.helper.next_fast_len(int(d)) for d in maxshape]
# pad out with reflection
pad_data = fft_pad(data, fshape, "reflect")
# calculate padding
padding = tuple(
_calc_pad(o, n) for o, n in zip(data.shape, pad_data.shape))
# so that we can calculate the cropping, maybe this should be integrated
# into `fft_pad` ...
fslice = tuple(
slice(s, -e) if e != 0 else slice(s, None) for s, e in padding)
if kernel.shape != pad_data.shape:
# its been assumed that the background of the kernel has already been
# removed and that the kernel has already been centered
kernel = fft_pad(kernel, pad_data.shape, mode='constant')
k_kernel = rfftn(ifftshift(kernel), pad_data.shape, **kwargs)
k_data = rfftn(pad_data, pad_data.shape, **kwargs)
convolve_data = irfftn(k_kernel * k_data, pad_data.shape, **kwargs)
# return data with same shape as original data
return convolve_data[fslice]
ax3.set_xlim([x1,x2-dx])
ax3.set_ylim([y1,y2-dy])
ax3.set_title("Spatial density (NUMERIC)")
ax2.imshow(phi.T, origin='lower', interpolation='none', extent=[px1,px2-dpx,py1,py2-dpy],vmin=amin(phi_exact), vmax=amax(phi_exact))
ax4.set_xlabel('x')
ax4.set_ylabel('y')
ax2.set_xlim([px1,px2-dpx])
ax2.set_ylim([py1,py2-dpy])
ax4.set_title("Momentum density (NUMERIC)")
plt.tight_layout()
fig.savefig('frames' + '/%04d.png' % k)
fig.clf()
plt.close('all')
dt = (t2-t1)/100. # the first very rough guess of time step
expU = exp(dt*dU)
expT = exp(dt*dT)
W = fftshift(gauss(xgrid, ygrid, pxgrid, pygrid, x0, y0, px0, py0, sigma_x, sigma_y, sigma_px, sigma_py))
t = t1
Nt = 1
while t <= t2:
Wexact = W_analytic(xgrid, ygrid, pxgrid, pygrid, t)
draw_frame(ifftshift(W), Wexact, Nt)
W = solve_spectral(W, expU, expT)
t += dt
Nt += 1
def multislice_propagate(grid_delta_batch,
grid_beta_batch,
probe_real,
probe_imag,
energy_ev,
psize_cm,
free_prop_cm=None,
return_intermediate=False,
sign_convention=1):
"""
Perform multislice propagation on a batch of 3D objects.
:param grid_delta_batch: 4D array for object delta with shape [n_batches, n_y, n_x, n_z].
:param grid_beta_batch: 4D array for object beta with shape [n_batches, n_y, n_x, n_z].
:param probe_real: 2D array for the real part of the probe.
:param probe_imag: 2D array for the imaginary part of the probe.
:param energy_ev:
:param psize_cm: size-3 vector with pixel size ([dy, dx, dz]).
:param free_prop_cm:
:return:
"""
minibatch_size = grid_delta_batch.shape[0]
grid_shape = grid_delta_batch.shape[1:]
voxel_nm = np.array(psize_cm) * 1.e7
wavefront = np.zeros([minibatch_size, grid_shape[0], grid_shape[1]],
dtype='complex64')
wavefront += (probe_real + 1j * probe_imag)
lmbda_nm = 1240. / energy_ev
mean_voxel_nm = np.prod(voxel_nm)**(1. / 3)
size_nm = np.array(grid_shape) * voxel_nm
n_slice = grid_shape[-1]
delta_nm = voxel_nm[-1]
# h = get_kernel_ir(delta_nm, lmbda_nm, voxel_nm, grid_shape)
h = get_kernel(delta_nm,
lmbda_nm,
voxel_nm,
grid_shape,
sign_convention=sign_convention)
k = 2. * PI * delta_nm / lmbda_nm
if return_intermediate:
wavefront_ls = []
wavefront_ls.append(abs(wavefront))
for i in trange(n_slice):
delta_slice = grid_delta_batch[:, :, :, i]
beta_slice = grid_beta_batch[:, :, :, i]
c = np.exp(1j * k * delta_slice) * np.exp(-k * beta_slice)
wavefront = wavefront * c
if i < n_slice - 1:
wavefront = ifft2(
ifftshift(fftshift(fft2(wavefront), axes=[1, 2]) * h,
axes=[1, 2]))
if return_intermediate:
wavefront_ls.append(abs(wavefront))
if free_prop_cm not in [None, 0]:
if free_prop_cm == 'inf':
wavefront = fftshift(fft2(wavefront), axes=[1, 2])
else:
dist_nm = free_prop_cm * 1e7
l = np.prod(size_nm)**(1. / 3)
crit_samp = lmbda_nm * dist_nm / l
algorithm = 'TF' if mean_voxel_nm > crit_samp else 'IR'
if algorithm == 'TF':
h = get_kernel(dist_nm,
lmbda_nm,
voxel_nm,
grid_shape,
sign_convention=sign_convention)
wavefront = ifft2(
ifftshift(fftshift(fft2(wavefront), axes=[1, 2]) * h,
axes=[1, 2]))
else:
h = get_kernel_ir(dist_nm,
lmbda_nm,
voxel_nm,
grid_shape,
sign_convention=sign_convention)
wavefront = ifft2(
ifftshift(fftshift(fft2(wavefront), axes=[1, 2]) * h,
axes=[1, 2]))
if return_intermediate:
if free_prop_cm not in [None, 0]:
wavefront_ls.append(abs(wavefront))
return wavefront, wavefront_ls
else:
return wavefront
def fft_convolve2d(x, f, mode='same', boundary='constant', fft_filter=False):
r"""
Performs fast 2d convolution in the frequency domain convolving each image
channel with its corresponding filter channel.
Parameters
----------
x : ``(channels, height, width)`` `ndarray`
Image.
f : ``(channels, height, width)`` `ndarray`
Filter.
mode : str {`full`, `same`, `valid`}, optional
Determines the shape of the resulting convolution.
boundary: str {`constant`, `symmetric`}, optional
Determines how the image is padded.
fft_filter: `bool`, optional
If `True`, the filter is assumed to be defined on the frequency
domain. If `False` the filter is assumed to be defined on the
spatial domain.
Returns
-------
c: ``(channels, height, width)`` `ndarray`
Result of convolving each image channel with its corresponding
filter channel.
"""
if fft_filter:
# extended shape is filter shape
ext_shape = np.asarray(f.shape[-2:])
# extend image and filter
ext_x = pad(x, ext_shape, boundary=boundary)
# compute ffts of extended image
fft_ext_x = fft2(ext_x)
fft_ext_f = f
else:
# extended shape
x_shape = np.asarray(x.shape[-2:])
f_shape = np.asarray(f.shape[-2:])
f_half_shape = (f_shape / 2).astype(int)
ext_shape = x_shape + f_half_shape - 1
# extend image and filter
ext_x = pad(x, ext_shape, boundary=boundary)
ext_f = pad(f, ext_shape)
# compute ffts of extended image and extended filter
fft_ext_x = fft2(ext_x)
fft_ext_f = fft2(ext_f)
# compute extended convolution in Fourier domain
fft_ext_c = fft_ext_f * fft_ext_x
# compute ifft of extended convolution
ext_c = np.real(ifftshift(ifft2(fft_ext_c), axes=(-2, -1)))
if mode is 'full':
return ext_c
elif mode is 'same':
return crop(ext_c, x_shape)
elif mode is 'valid':
return crop(ext_c, x_shape - f_half_shape + 1)
else:
raise ValueError(
"mode={}, is not supported. The only supported "
"modes are: 'full', 'same' and 'valid'.".format(mode))
def retrieve_phase(data,
params,
max_iters=200,
pupil_tol=1e-8,
mse_tol=1e-8,
phase_only=False,
mclass=HanserPSF):
"""Retrieve the phase across the objective's back pupil from an
experimentally measured PSF.
Follows: [Hanser, B. M.; Gustafsson, M. G. L.; Agard, D. A.;
Sedat, J. W. Phase Retrieval for High-Numerical-Aperture Optical Systems.
Optics Letters 2003, 28 (10), 801.](dx.doi.org/10.1364/OL.28.000801)
Parameters
----------
data : ndarray (3 dim)
The experimentally measured PSF of a subdiffractive source
params : dict
Parameters to pass to HanserPSF, size and zsize will be automatically
updated from data.shape
max_iters : int
The maximum number of iterations to run, default is 200
pupil_tol : float
the tolerance in percent change in change in pupil, default is 1e-8
mse_tol : float
the tolerance in percent change for the mean squared error between
data and simulated data, default is 1e-8
phase_only : bool
True means only the phase of the back pupil is retrieved while the
amplitude is not.
Returns
-------
PR_result : PhaseRetrievalResult
An object that contains the phase retrieval result
"""
# make sure data is square
assert data.shape[1] == data.shape[2], "Data is not square in x/y"
assert data.ndim == 3, "Data doesn't have enough dims"
# make sure the user hasn't screwed up the params
params.update(
dict(vec_corr="none",
condition="none",
zsize=data.shape[0],
size=data.shape[-1]))
# assume that data prep has been handled outside function
# The field magnitude is the square root of the intensity
mag = psqrt(data)
# generate a model from parameters
model = mclass(**params)
# generate coordinates
model._gen_kr()
# start a list for iteration
mse = np.zeros(max_iters)
mse_diff = np.zeros(max_iters)
pupil_diff = np.zeros(max_iters)
# generate a pupil to start with
new_pupil = model._gen_pupil()
# save it as a mask
mask = new_pupil.real
# iterate
old_mse, old_pupil = None, None
for i in range(max_iters):
# generate new mse and add it to the list
model._gen_psf(new_pupil)
new_mse = _calc_mse(data, model.PSFi)
mse[i] = new_mse
if i > 0:
# calculate the difference in mse to test for convergence
mse_diff[i] = abs(old_mse - new_mse) / old_mse
# calculate the difference in pupil
pupil_diff[i] = (abs(old_pupil - new_pupil)**
2).mean() / (abs(old_pupil)**2).mean()
else:
mse_diff[i] = np.nan
pupil_diff[i] = np.nan
# check tolerances, how much has the pupil changed, how much has the mse changed
# and what's the absolute mse
logger.info(
"Iteration {}, mse_diff = {:.2g}, pupil_diff = {:.2g}".format(
i, mse_diff[i], pupil_diff[i]))
if pupil_diff[i] < pupil_tol or mse_diff[i] < mse_tol or mse[
i] < mse_tol:
break
# update old_mse
old_mse = new_mse
# retrieve new pupil
old_pupil = new_pupil
# keep phase
phase = np.angle(model.PSFa.squeeze())
# replace magnitude with experimentally measured mag
new_psf = mag * np.exp(1j * phase)
# generate the new pupils
new_pupils = fftn(ifftshift(new_psf, axes=(1, 2)), axes=(1, 2))
# undo defocus and take the mean
new_pupils /= model._calc_defocus()
new_pupil = new_pupils.mean(0) * mask
# if phase only discard magnitude info
if phase_only:
new_pupil = np.exp(1j * np.angle(new_pupil)) * mask
else:
logger.warn("Reach max iterations without convergence")
mse = mse[:i + 1]
mse_diff = mse_diff[:i + 1]
pupil_diff = pupil_diff[:i + 1]
# shift mask
mask = fftshift(mask)
# shift phase then unwrap and mask
phase = unwrap_phase(fftshift(np.angle(new_pupil))) * mask
# shift magnitude
magnitude = fftshift(abs(new_pupil)) * mask
return PhaseRetrievalResult(magnitude, phase, mse, pupil_diff, mse_diff,
model)
def ifftnc(x, axes):
tmp = fft.fftshift(x, axes=axes)
tmp = fft.ifftn(tmp, axes=axes)
return fft.ifftshift(tmp, axes=axes)
def process_frames(self, data):
sino = fft.fftshift(self.fft_object(data[0]))
sino[self.row1:self.row2] = \
sino[self.row1:self.row2] * self.filtercomplex
sino = fft.ifftshift(sino)
return self.ifft_object(sino).real
def set_pulse_shapes(self, pump_field, probe_field, *, plot_fields=True):
"""Sets a list of 4 pulse amplitudes, given an input pump shape and probe
shape. Assumes 4-wave mixing signals, and so 4 interactions
"""
self.efields = [pump_field, pump_field, probe_field, probe_field]
if self.efield_t.size == 1:
pass
else:
pump_tail = np.max(np.abs([pump_field[0], pump_field[-1]]))
probe_tail = np.max(np.abs([probe_field[0], probe_field[-1]]))
if pump_field.size != self.efield_t.size:
warnings.warn(
'Pump must be evaluated on efield_t, the grid defined by dt and num_conv_points'
)
if probe_field.size != self.efield_t.size:
warnings.warn(
'Probe must be evaluated on efield_t, the grid defined by dt and num_conv_points'
)
if pump_tail > np.max(np.abs(pump_field)) / 100:
warnings.warn(
'Consider using larger num_conv_points, pump does not decay to less than 1% of maximum value in time domain'
)
if probe_tail > np.max(np.abs(probe_field)) / 100:
warnings.warn(
'Consider using larger num_conv_points, probe does not decay to less than 1% of maximum value in time domain'
)
pump_fft = fftshift(fft(ifftshift(pump_field))) * self.dt
probe_fft = fftshift(fft(ifftshift(probe_field))) * self.dt
pump_fft_tail = np.max(np.abs([pump_fft[0], pump_fft[-1]]))
probe_fft_tail = np.max(np.abs([probe_fft[0], probe_fft[-1]]))
if pump_fft_tail > np.max(np.abs(pump_fft)) / 100:
warnings.warn(
'''Consider using smaller value of dt, pump does not decay to less than 1% of maximum value in frequency domain'''
)
if probe_fft_tail > np.max(np.abs(probe_fft)) / 100:
warnings.warn(
'''Consider using smaller value of dt, probe does not decay to less than 1% of maximum value in frequency domain'''
)
if plot_fields:
fig, axes = plt.subplots(2, 2)
l1, l2, = axes[0, 0].plot(self.efield_t, np.real(pump_field),
self.efield_t, np.imag(pump_field))
plt.legend([l1, l2], ['Real', 'Imag'])
axes[0, 1].plot(self.efield_w, np.real(pump_fft),
self.efield_w, np.imag(pump_fft))
axes[1, 0].plot(self.efield_t, np.real(probe_field),
self.efield_t, np.imag(probe_field))
axes[1, 1].plot(self.efield_w, np.real(probe_fft),
self.efield_w, np.imag(probe_fft))
axes[0, 0].set_ylabel('Pump Amp')
axes[1, 0].set_ylabel('Probe Amp')
axes[1, 0].set_xlabel('Time')
axes[1, 1].set_xlabel('Frequency')
fig.suptitle(
'Check that pump and probe are well-resolved in time and frequency'
)
def py_zogy(Nf, Rf, P_Nf, P_Rf, S_Nf, S_Rf, SN, SR, dx=0.25, dy=0.25): '''Python implementation of ZOGY image subtraction algorithm. As per Frank's instructions, will assume images have been aligned, background subtracted, and gain-matched. Arguments: N: New image (filename) R: Reference image (filename) P_N: PSF of New image (filename) P_R: PSF or Reference image (filename) S_N: 2D Uncertainty (sigma) of New image (filename) S_R: 2D Uncertainty (sigma) of Reference image (filename) SN: Average uncertainty (sigma) of New image SR: Average uncertainty (sigma) of Reference image dx: Astrometric uncertainty (sigma) in x coordinate dy: Astrometric uncertainty (sigma) in y coordinate Returns: D: Subtracted image P_D: PSF of subtracted image S_corr: Corrected subtracted image ''' # Load the new and ref images into memory N = fits.open(Nf)[0].data R = fits.open(Rf)[0].data # Load the PSFs into memory P_N_small = fits.open(P_Nf)[0].data P_R_small = fits.open(P_Rf)[0].data # Place PSF at center of image with same size as new / reference P_N = np.zeros(N.shape) P_R = np.zeros(R.shape) idx = [slice(N.shape[0]/2 - P_N_small.shape[0]/2, N.shape[0]/2 + P_N_small.shape[0]/2 + 1), slice(N.shape[1]/2 - P_N_small.shape[1]/2, N.shape[1]/2 + P_N_small.shape[1]/2 + 1)] P_N[idx] = P_N_small P_R[idx] = P_R_small # Shift the PSF to the origin so it will not introduce a shift P_N = fft.fftshift(P_N) P_R = fft.fftshift(P_R) # Take all the Fourier Transforms N_hat = fft.fft2(N) R_hat = fft.fft2(R) P_N_hat = fft.fft2(P_N) P_R_hat = fft.fft2(P_R) # Fourier Transform of Difference Image (Equation 13) D_hat_num = (P_R_hat * N_hat - P_N_hat * R_hat) D_hat_den = np.sqrt(SN**2 * np.abs(P_R_hat**2) + SR**2 * np.abs(P_N_hat**2)) D_hat = D_hat_num / D_hat_den # Flux-based zero point (Equation 15) FD = 1. / np.sqrt(SN**2 + SR**2) # Difference Image # TODO: Why is the FD normalization in there? D = np.real(fft.ifft2(D_hat)) / FD # Fourier Transform of PSF of Subtraction Image (Equation 14) P_D_hat = P_R_hat * P_N_hat / FD / D_hat_den # PSF of Subtraction Image P_D = np.real(fft.ifft2(P_D_hat)) P_D = fft.ifftshift(P_D) P_D = P_D[idx] # Fourier Transform of Score Image (Equation 17) S_hat = FD * D_hat * np.conj(P_D_hat) # Score Image S = np.real(fft.ifft2(S_hat)) # Now start calculating Scorr matrix (including all noise terms) # Start out with source noise # Load the sigma images into memory S_N = fits.open(S_Nf)[0].data S_R = fits.open(S_Rf)[0].data # Sigma to variance V_N = S_N**2 V_R = S_R**2 # Fourier Transform of variance images V_N_hat = fft.fft2(V_N) V_R_hat = fft.fft2(V_R) # Equation 28 kr_hat = np.conj(P_R_hat) * np.abs(P_N_hat**2) / (D_hat_den**2) kr = np.real(fft.ifft2(kr_hat)) # Equation 29 kn_hat = np.conj(P_N_hat) * np.abs(P_R_hat**2) / (D_hat_den**2) kn = np.real(fft.ifft2(kn_hat)) # Noise in New Image: Equation 26 V_S_N = np.real(fft.ifft2(V_N_hat * fft.fft2(kn**2))) # Noise in Reference Image: Equation 27 V_S_R = np.real(fft.ifft2(V_R_hat * fft.fft2(kr**2))) # Astrometric Noise # Equation 31 # TODO: Check axis (0/1) vs x/y coordinates S_N = np.real(fft.ifft2(kn_hat * N_hat)) dSNdx = S_N - np.roll(S_N, 1, axis=1) dSNdy = S_N - np.roll(S_N, 1, axis=0) # Equation 30 V_ast_S_N = dx**2 * dSNdx**2 + dy**2 * dSNdy**2 # Equation 33 S_R = np.real(fft.ifft2(kr_hat * R_hat)) dSRdx = S_R - np.roll(S_R, 1, axis=1) dSRdy = S_R - np.roll(S_R, 1, axis=0) # Equation 32 V_ast_S_R = dx**2 * dSRdx**2 + dy**2 * dSRdy**2 # Calculate Scorr S_corr = S / np.sqrt(V_S_N + V_S_R + V_ast_S_N + V_ast_S_R) return D, P_D, S_corr
def fillWithGRFFromTemplate(self, twodPower, bufferFactor=1, threads=1):
"""
Generate a Gaussian random field from an input power spectrum
specified as a 2d powerMap
Notes
-----
BufferFactor = 1 means the map will have periodic boundary function, while
BufferFactor > 1 means the map will be genrated on a patch bufferFactor
times larger in each dimension and then cut out so as to have
non-periodic boundary conditions.
Fills the data field of the map with the GRF realization.
"""
ft = fftTools.fftFromLiteMap(self, threads=threads)
Ny = self.Ny * bufferFactor
Nx = self.Nx * bufferFactor
bufferFactor = int(bufferFactor)
assert bufferFactor >= 1
realPart = numpy.zeros([Ny, Nx])
imgPart = numpy.zeros([Ny, Nx])
ly = fftfreq(Ny, d=self.pixScaleY) * (2 * numpy.pi)
lx = fftfreq(Nx, d=self.pixScaleX) * (2 * numpy.pi)
# print ly
modLMap = numpy.zeros([Ny, Nx])
iy, ix = numpy.mgrid[0:Ny, 0:Nx]
modLMap[iy, ix] = numpy.sqrt(ly[iy] ** 2 + lx[ix] ** 2)
# divide out area factor
area = twodPower.Nx * twodPower.Ny * twodPower.pixScaleX * twodPower.pixScaleY
twodPower.powerMap *= (twodPower.Nx * twodPower.Ny) ** 2 / area
if bufferFactor > 1 or twodPower.Nx != Nx or twodPower.Ny != Ny:
lx_shifted = fftshift(twodPower.lx)
ly_shifted = fftshift(twodPower.ly)
twodPower_shifted = fftshift(twodPower.powerMap)
f_interp = interp2d(lx_shifted, ly_shifted, twodPower_shifted)
# ell = numpy.ravel(twodPower.modLMap)
# Cell = numpy.ravel(twodPower.powerMap)
# print ell
# print Cell
# s = splrep(ell,Cell,k=3)
#
#
# ll = numpy.ravel(modLMap)
# kk = splev(ll,s)
kk = f_interp(fftshift(lx), fftshift(ly))
kk = ifftshift(kk)
# id = numpy.where(modLMap > ell.max())
# kk[id] = 0.
# add a cosine ^2 falloff at the very end
# id2 = numpy.where( (ll> (ell.max()-500)) & (ll<ell.max()))
# lEnd = ll[id2]
# kk[id2] *= numpy.cos((lEnd-lEnd.min())/(lEnd.max() -lEnd.min())*numpy.pi/2)
# pylab.loglog(ll,kk)
area = Nx * Ny * self.pixScaleX * self.pixScaleY
# p = numpy.reshape(kk,[Ny,Nx]) /area * (Nx*Ny)**2
p = kk # / area * (Nx*Ny)**2
else:
area = Nx * Ny * self.pixScaleX * self.pixScaleY
p = twodPower.powerMap # /area*(Nx*Ny)**2
realPart = numpy.sqrt(p) * numpy.random.randn(Ny, Nx)
imgPart = numpy.sqrt(p) * numpy.random.randn(Ny, Nx)
kMap = realPart + 1j * imgPart
if have_pyFFTW:
data = numpy.real(ifft2(kMap, threads=threads))
else:
data = numpy.real(ifft2(kMap))
b = bufferFactor
self.data = data[(b - 1) / 2 * self.Ny : (b + 1) / 2 * self.Ny, (b - 1) / 2 * self.Nx : (b + 1) / 2 * self.Nx]
def upgradePixelPitch(m, N=1, threads=1):
"""
Go to finer pixels with fourier interpolation.
Parameters
----------
m : liteMap
The liteMap object holding the data to upgrade the pixel size of.
N : int, optional
Go to 2^N times smaller pixels. Default is 1.
threads : int, optional
Number of threads to use in pyFFTW calculations. Default is 1.
Returns
-------
mNew : liteMap
The map with smaller pixels.
"""
if N < 1:
return m.copy()
Ny = m.Ny * 2 ** N
Nx = m.Nx * 2 ** N
npix = Ny * Nx
if have_pyFFTW:
ft = fft2(m.data, threads=threads)
else:
ft = fft2(m.data)
ftShifted = fftshift(ft)
newFtShifted = numpy.zeros((Ny, Nx), dtype=numpy.complex128)
# From the numpy.fft.fftshift help:
# """
# Shift zero-frequency component to center of spectrum.
#
# This function swaps half-spaces for all axes listed (defaults to all).
# If len(x) is even then the Nyquist component is y[0].
# """
#
# So in the case that we have an odd dimension in our map, we want to put
# the extra zero at the beginning
if m.Nx % 2 != 0:
offsetX = (Nx - m.Nx) / 2 + 1
else:
offsetX = (Nx - m.Nx) / 2
if m.Ny % 2 != 0:
offsetY = (Ny - m.Ny) / 2 + 1
else:
offsetY = (Ny - m.Ny) / 2
newFtShifted[offsetY : offsetY + m.Ny, offsetX : offsetX + m.Nx] = ftShifted
del ftShifted
ftNew = ifftshift(newFtShifted)
del newFtShifted
# Finally, deconvolve by the pixel window
mPix = numpy.copy(numpy.real(ftNew))
mPix[:] = 0.0
mPix[
mPix.shape[0] / 2 - (2 ** (N - 1)) : mPix.shape[0] / 2 + (2 ** (N - 1)),
mPix.shape[1] / 2 - (2 ** (N - 1)) : mPix.shape[1] / 2 + (2 ** (N - 1)),
] = (1.0 / (2.0 ** N) ** 2)
if have_pyFFTW:
ftPix = fft2(mPix, threads=threads)
else:
ftPix = fft2(mPix)
del mPix
inds = numpy.where(ftNew != 0)
ftNew[inds] /= numpy.abs(ftPix[inds])
if have_pyFFTW:
newData = ifft2(ftNew, threads=threads) * (2 ** N) ** 2
else:
newData = ifft2(ftNew) * (2 ** N) ** 2
del ftNew
del ftPix
x0_new, y0_new = m.pixToSky(0, 0)
m = m.copy() # don't overwrite original
m.wcs.header.update("NAXIS1", 2 ** N * m.wcs.header["NAXIS1"])
m.wcs.header.update("NAXIS2", 2 ** N * m.wcs.header["NAXIS2"])
m.wcs.header.update("CDELT1", m.wcs.header["CDELT1"] / 2.0 ** N)
m.wcs.header.update("CDELT2", m.wcs.header["CDELT2"] / 2.0 ** N)
m.wcs.updateFromHeader()
p_x, p_y = m.skyToPix(x0_new, y0_new)
m.wcs.header.update("CRPIX1", m.wcs.header["CRPIX1"] - p_x)
m.wcs.header.update("CRPIX2", m.wcs.header["CRPIX2"] - p_y)
m.wcs.updateFromHeader()
mNew = liteMapFromDataAndWCS(numpy.real(newData), m.wcs)
mNew.data[:] = numpy.real(newData[:])
return mNew
def process_frames(self, data):
sino = fft.fftshift(self.fft_object(data[0]))
sino[self.row1:self.row2] = \
sino[self.row1:self.row2] * self.filtercomplex
sino = fft.ifftshift(sino)
return self.ifft_object(sino).real
def fft_convolve2d(x, f, mode='same', boundary='constant', fft_filter=False):
r"""
Performs fast 2d convolution in the frequency domain convolving each image
channel with its corresponding filter channel.
Parameters
----------
x : ``(channels, height, width)`` `ndarray`
Image.
f : ``(channels, height, width)`` `ndarray`
Filter.
mode : str {`full`, `same`, `valid`}, optional
Determines the shape of the resulting convolution.
boundary: str {`constant`, `symmetric`}, optional
Determines how the image is padded.
fft_filter: `bool`, optional
If `True`, the filter is assumed to be defined on the frequency
domain. If `False` the filter is assumed to be defined on the
spatial domain.
Returns
-------
c: ``(channels, height, width)`` `ndarray`
Result of convolving each image channel with its corresponding
filter channel.
"""
if fft_filter:
# extended shape is filter shape
ext_shape = np.asarray(f.shape[-2:])
# extend image and filter
ext_x = pad(x, ext_shape, boundary=boundary)
# compute ffts of extended image
fft_ext_x = fft2(ext_x)
fft_ext_f = f
else:
# extended shape
x_shape = np.asarray(x.shape[-2:])
f_shape = np.asarray(f.shape[-2:])
f_half_shape = (f_shape / 2).astype(int)
ext_shape = x_shape + f_half_shape - 1
# extend image and filter
ext_x = pad(x, ext_shape, boundary=boundary)
ext_f = pad(f, ext_shape)
# compute ffts of extended image and extended filter
fft_ext_x = fft2(ext_x)
fft_ext_f = fft2(ext_f)
# compute extended convolution in Fourier domain
fft_ext_c = fft_ext_f * fft_ext_x
# compute ifft of extended convolution
ext_c = np.real(ifftshift(ifft2(fft_ext_c), axes=(-2, -1)))
if mode is 'full':
return ext_c
elif mode is 'same':
return crop(ext_c, x_shape)
elif mode is 'valid':
return crop(ext_c, x_shape - f_half_shape + 1)
else:
raise ValueError("mode={}, is not supported. The only supported "
"modes are: 'full', 'same' and 'valid'.".format(mode))
