Python numpy.fft.ifft2() Examples
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code examples of numpy.fft.ifft2().
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Example #1
Source File: functions.py From prnu-python with MIT License | 6 votes |
def wiener_dft(im: np.ndarray, sigma: float) -> np.ndarray: """ Adaptive Wiener filter applied to the 2D FFT of the image :param im: multidimensional array :param sigma: estimated noise power :return: filtered version of input im """ noise_var = sigma ** 2 h, w = im.shape im_noise_fft = fft2(im) im_noise_fft_mag = np.abs(im_noise_fft / (h * w) ** .5) im_noise_fft_mag_noise = wiener_adaptive(im_noise_fft_mag, noise_var) zeros_y, zeros_x = np.nonzero(im_noise_fft_mag == 0) im_noise_fft_mag[zeros_y, zeros_x] = 1 im_noise_fft_mag_noise[zeros_y, zeros_x] = 0 im_noise_fft_filt = im_noise_fft * im_noise_fft_mag_noise / im_noise_fft_mag im_noise_filt = np.real(ifft2(im_noise_fft_filt)) return im_noise_filt.astype(np.float32)
Example #2
Source File: functions.py From prnu-python with MIT License | 6 votes |
def crosscorr_2d(k1: np.ndarray, k2: np.ndarray) -> np.ndarray: """ PRNU 2D cross-correlation :param k1: 2D matrix of size (h1,w1) :param k2: 2D matrix of size (h2,w2) :return: 2D matrix of size (max(h1,h2),max(w1,w2)) """ assert (k1.ndim == 2) assert (k2.ndim == 2) max_height = max(k1.shape[0], k2.shape[0]) max_width = max(k1.shape[1], k2.shape[1]) k1 -= k1.flatten().mean() k2 -= k2.flatten().mean() k1 = np.pad(k1, [(0, max_height - k1.shape[0]), (0, max_width - k1.shape[1])], mode='constant', constant_values=0) k2 = np.pad(k2, [(0, max_height - k2.shape[0]), (0, max_width - k2.shape[1])], mode='constant', constant_values=0) k1_fft = fft2(k1, ) k2_fft = fft2(np.rot90(k2, 2), ) return np.real(ifft2(k1_fft * k2_fft)).astype(np.float32)
Example #3
Source File: fft.py From pysteps with BSD 3-Clause "New" or "Revised" License | 6 votes |
def get_numpy(shape, fftn_shape=None, **kwargs): import numpy.fft as numpy_fft f = { "fft2": numpy_fft.fft2, "ifft2": numpy_fft.ifft2, "rfft2": numpy_fft.rfft2, "irfft2": lambda X: numpy_fft.irfft2(X, s=shape), "fftshift": numpy_fft.fftshift, "ifftshift": numpy_fft.ifftshift, "fftfreq": numpy_fft.fftfreq, } if fftn_shape is not None: f["fftn"] = numpy_fft.fftn fft = SimpleNamespace(**f) return fft
Example #4
Source File: fft.py From pysteps with BSD 3-Clause "New" or "Revised" License | 6 votes |
def get_scipy(shape, fftn_shape=None, **kwargs): import numpy.fft as numpy_fft import scipy.fftpack as scipy_fft # use numpy implementation of rfft2/irfft2 because they have not been # implemented in scipy.fftpack f = { "fft2": scipy_fft.fft2, "ifft2": scipy_fft.ifft2, "rfft2": numpy_fft.rfft2, "irfft2": lambda X: numpy_fft.irfft2(X, s=shape), "fftshift": scipy_fft.fftshift, "ifftshift": scipy_fft.ifftshift, "fftfreq": scipy_fft.fftfreq, } if fftn_shape is not None: f["fftn"] = scipy_fft.fftn fft = SimpleNamespace(**f) return fft
Example #5
Source File: T2FFT.py From lie_learn with MIT License | 5 votes |
def synthesize(f_hat, axes=(0, 1)): """ :param f_hat: :param axis: :return: """ size = np.prod([f_hat.shape[ax] for ax in axes]) f_hat = ifftshift(f_hat * size, axes=axes) f = ifft2(f_hat, axes=axes) return f
Example #6
Source File: utils.py From ProxImaL with MIT License | 5 votes |
def ifftd(I, dims=None): # Compute fft if dims is None: X = ifftn(I) elif dims == 2: X = ifft2(I, axes=(0, 1)) else: X = ifftn(I, axes=tuple(range(dims))) return X
Example #7
Source File: imageprocess.py From picasso with MIT License | 5 votes |
def xcorr(imageA, imageB): FimageA = _fft.fft2(imageA) CFimageB = _np.conj(_fft.fft2(imageB)) return _fft.fftshift( _np.real(_fft.ifft2((FimageA * CFimageB))) ) / _np.sqrt(imageA.size)
Example #8
Source File: helper.py From tierpsy-tracker with MIT License | 5 votes |
def fft_convolve2d(x,y): """ 2D convolution, using FFT""" fr = fft2(x) fr2 = fft2(y) cc = np.real(ifft2(fr*fr2)) cc = fftshift(cc) return cc
Example #9
Source File: lib.py From game-of-life with Apache License 2.0 | 5 votes |
def fft_convolve2d(x,y): """ 2D convolution, using FFT """ fr = fft2(x) fr2 = fft2(np.flipud(np.fliplr(y))) m,n = fr.shape cc = np.real(ifft2(fr*fr2)) cc = np.roll(cc, - int(m / 2) + 1, axis=0) cc = np.roll(cc, - int(n / 2) + 1, axis=1) return cc
Example #10
Source File: shearlab_operator.py From odl with Mozilla Public License 2.0 | 5 votes |
def sheardec2D(X, shearletsystem): """Shearlet Decomposition function.""" coeffs = np.zeros(shearletsystem.shearlets.shape, dtype=complex) Xfreq = fftshift(fft2(ifftshift(X))) for i in range(shearletsystem.nShearlets): coeffs[:, :, i] = fftshift(ifft2(ifftshift(Xfreq * np.conj( shearletsystem.shearlets[:, :, i])))) return coeffs.real
Example #11
Source File: shearlab_operator.py From odl with Mozilla Public License 2.0 | 5 votes |
def shearrec2D(coeffs, shearletsystem): """Shearlet Recovery function.""" X = np.zeros(coeffs.shape[:2], dtype=complex) for i in range(shearletsystem.nShearlets): X = X + fftshift(fft2( ifftshift(coeffs[:, :, i]))) * shearletsystem.shearlets[:, :, i] return (fftshift(ifft2(ifftshift(( X / shearletsystem.dualFrameWeights))))).real
Example #12
Source File: shearlab_operator.py From odl with Mozilla Public License 2.0 | 5 votes |
def sheardecadjoint2D(coeffs, shearletsystem): """Shearlet Decomposition adjoint function.""" X = np.zeros(coeffs.shape[:2], dtype=complex) for i in range(shearletsystem.nShearlets): X = X + fftshift(fft2( ifftshift(coeffs[:, :, i]))) * np.conj( shearletsystem.shearlets[:, :, i]) return (fftshift(ifft2(ifftshift( X / shearletsystem.dualFrameWeights)))).real
Example #13
Source File: shearlab_operator.py From odl with Mozilla Public License 2.0 | 5 votes |
def shearrecadjoint2D(X, shearletsystem): """Shearlet Recovery adjoint function.""" coeffs = np.zeros(shearletsystem.shearlets.shape, dtype=complex) Xfreq = fftshift(fft2(ifftshift(X))) for i in range(shearletsystem.nShearlets): coeffs[:, :, i] = fftshift(ifft2(ifftshift( Xfreq * shearletsystem.shearlets[:, :, i]))) return coeffs.real
Example #14
Source File: gs.py From pyoptools with GNU General Public License v3.0 | 4 votes |
def gs(idata,itera=10, ia=None): """Gerchberg-Saxton algorithm to calculate DOEs Calculates the phase distribution in a object plane to obtain an specific amplitude distribution in the target plane. It uses a FFT to calculate the field propagation. The wavefront at the DOE plane is assumed as a plane wave. **ARGUMENTS:** ========== ======================================================== idata numpy array containing the target amplitude distribution itera Maximum number of iterations ia Illumination amplitude at the hologram plane if not given it is assumed to be a constant amplitude with a value of 1. If given it should be an array with the same shape of idata ========== ======================================================== """ if ia==None: inpa=ones(idata.shape) else: inpa=ia assert idata.shape==inpa.shape, "ia and idata must have the same dimensions" fdata=fftshift(fft2(ifftshift(idata))) e=1000 ea=1000 for i in range (itera): fdata=exp(1.j*angle(fdata))*inpa rdata=ifftshift(ifft2(fftshift(fdata))) e= (abs(rdata)-idata).std() if e>ea: break ea=e rdata=exp(1.j*angle(rdata))*(idata) fdata=fftshift(fft2(ifftshift(rdata))) fdata=exp(1.j*angle(fdata)) return fdata*inpa
Example #15
Source File: gs.py From pyoptools with GNU General Public License v3.0 | 4 votes |
def gs_mod(idata,itera=10,osize=256): """Modiffied Gerchberg-Saxton algorithm to calculate DOEs Calculates the phase distribution in a object plane to obtain an specific amplitude distribution in the target plane. It uses a FFT to calculate the field propagation. The wavefront at the DOE plane is assumed as a plane wave. This algorithm leaves a window around the image plane to allow the noise to move there. It only optimises the center of the image. **ARGUMENTS:** ========== ====================================================== idata numpy array containing the target amplitude distribution itera Maximum number of iterations osize Size of the center of the image to be optimized It should be smaller than the image itself. ========== ====================================================== """ M,N=idata.shape cut=osize//2 zone=zeros_like(idata) zone[M/2-cut:M/2+cut,N/2-cut:N/2+cut]=1 zone=zone.astype(bool) mask=exp(2.j*pi*random(idata.shape)) mask[zone]=0 #~ imshow(abs(mask)),colorbar() fdata=fftshift(fft2(ifftshift(idata+mask))) #Nota, colocar esta mascara es muy importante, por que si no no converge tan rapido e=1000 ea=1000 for i in range (itera): fdata=exp(1.j*angle(fdata)) rdata=ifftshift(ifft2(fftshift(fdata))) #~ e= (abs(rdata[zone])-idata[zone]).std() #~ if e>ea: #~ #~ break ea=e rdata[zone]=exp(1.j*angle(rdata[zone]))*(idata[zone]) fdata=fftshift(fft2(ifftshift(rdata))) fdata=exp(1.j*angle(fdata)) return fdata