Python numpy.fft.fft2() Examples
The following are 23 code examples for showing how to use numpy.fft.fft2(). These examples are extracted from open source projects. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example.
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Example 1
Project: opticspy Author: Sterncat File: zernike.py License: MIT License | 6 votes |
def ptf(self): """ Phase transfer function """ PSF = self.__psfcaculator__() PTF = __fftshift__(__fft2__(PSF)) PTF = __np__.angle(PTF) b = 400 R = (200)**2 for i in range(b): for j in range(b): if (i-b/2)**2+(j-b/2)**2>R: PTF[i][j] = 0 __plt__.imshow(abs(PTF),cmap=__cm__.rainbow) __plt__.colorbar() __plt__.show() return 0
Example 2
Project: prnu-python Author: polimi-ispl File: functions.py License: 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 3
Project: prnu-python Author: polimi-ispl File: functions.py License: 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 4
Project: pytorch_fft Author: locuslab File: test.py License: Apache License 2.0 | 6 votes |
def test_expand(): X = torch.randn(2,2,4,4).cuda().double() zeros = torch.zeros(2,2,4,4).cuda().double() r1, r2 = cfft.rfft2(X) c1, c2 = cfft.fft2(X, zeros) assert np.allclose(cfft.expand(r1).cpu().numpy(), c1.cpu().numpy()) assert np.allclose(cfft.expand(r2, imag=True).cpu().numpy(), c2.cpu().numpy()) r1, r2 = cfft.rfft3(X) c1, c2 = cfft.fft3(X, zeros) assert np.allclose(cfft.expand(r1).cpu().numpy(), c1.cpu().numpy()) assert np.allclose(cfft.expand(r2, imag=True).cpu().numpy(), c2.cpu().numpy()) X = torch.randn(2,2,5,5).cuda().double() zeros = torch.zeros(2,2,5,5).cuda().double() r1, r2 = cfft.rfft3(X) c1, c2 = cfft.fft3(X, zeros) assert np.allclose(cfft.expand(r1, odd=True).cpu().numpy(), c1.cpu().numpy()) assert np.allclose(cfft.expand(r2, imag=True, odd=True).cpu().numpy(), c2.cpu().numpy())
Example 5
Project: pysteps Author: pySTEPS File: fft.py License: 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 6
Project: pysteps Author: pySTEPS File: fft.py License: 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 7
Project: lie_learn Author: AMLab-Amsterdam File: T2FFT.py License: MIT License | 5 votes |
def analyze(f, axes=(0, 1)): """ Compute the Fourier Transform of the discretely sampled function f : T^2 -> C. Let f : T^2 -> C be a band-limited function on the torus. The samples f(theta_k, phi_l) correspond to points on a regular grid on the circle, as returned by spaces.T1.linspace: theta_k = phi_k = 2 pi k / N for k = 0, ..., N - 1 and l = 0, ..., N - 1 This function computes \hat{f}_n = (1/N) \sum_{k=0}^{N-1} f(theta_k) e^{-i n theta_k} which, if f has band-limit less than N, is equal to: \hat{f}_n = \int_0^{2pi} f(theta) e^{-i n theta} dtheta / 2pi, = <f(theta), e^{i n theta}> where dtheta / 2pi is the normalized Haar measure on T^1, and < , > denotes the inner product on Hilbert space, with respect to which this transform is unitary. The range of frequencies n is -floor(N/2) <= n <= ceil(N/2) - 1 :param f: :param axis: :return: """ # The numpy FFT returns coefficients in a different order than we want them, # and using a different normalization. f_hat = fft2(f, axes=axes) f_hat = fftshift(f_hat, axes=axes) size = np.prod([f.shape[ax] for ax in axes]) return f_hat / size
Example 8
Project: opticspy Author: Sterncat File: zernike_rec.py License: MIT License | 5 votes |
def __psfcaculator__(self,lambda_1=632*10**(-9),z=0.1): """ height: Exit pupil height width: Exit pupil width z: Distance from exit pupil to image plane """ a = self.__a__ b = __sqrt__(1-a**2) l1 = 100; x1 = __np__.linspace(-a, a, l1) y1 = __np__.linspace(-b, b, l1) [X,Y] = __np__.meshgrid(x1,y1) Z = __zernikecartesian__(self.__coefficients__,a,X,Y) d = 400 # background A = __np__.zeros([d,d]) A[d//2-l1//2+1:d//2+l1//2+1,d//2-l1//2+1:d//2+l1//2+1] = Z # fig = __plt__.figure() # __plt__.imshow(A) # __plt__.colorbar() # __plt__.show() abbe = __np__.exp(-1j*2*__np__.pi*A) for i in range(len(abbe)): for j in range(len(abbe)): if abbe[i][j]==1: abbe[i][j]=0 PSF = __fftshift__(__fft2__(__fftshift__(abbe)))**2 PSF = PSF/PSF.max() return PSF
Example 9
Project: opticspy Author: Sterncat File: zernike_rec.py License: MIT License | 5 votes |
def mtf(self,lambda_1=632*10**(-9),z=0.1,matrix = False): """ Modulate Transfer function """ PSF = self.__psfcaculator__(lambda_1=lambda_1,z=z) MTF = __fftshift__(__fft2__(PSF)) MTF = MTF/MTF.max() fig = __plt__.figure(figsize=(9, 6), dpi=80) __plt__.imshow(abs(MTF),cmap=__cm__.bwr) __plt__.colorbar() __plt__.show() if matrix == True: return MTF else: return 0
Example 10
Project: opticspy Author: Sterncat File: zernike_rec.py License: MIT License | 5 votes |
def ptf(self): """ Phase transfer function """ PSF = self.__psfcaculator__() PTF = __fftshift__(__fft2__(PSF)) PTF = __np__.angle(PTF) l1 = 100 d = 400 A = __np__.zeros([d,d]) A[d//2-l1//2+1:d//2+l1//2+1,d//2-l1//2+1:d//2+l1//2+1] = PTF[d//2-l1//2+1:d//2+l1//2+1,d//2-l1//2+1:d//2+l1//2+1] __plt__.imshow(abs(A),cmap=__cm__.rainbow) __plt__.colorbar() __plt__.show() return 0
Example 11
Project: opticspy Author: Sterncat File: zernike.py License: MIT License | 5 votes |
def __psfcaculator__(self,r=1,lambda_1=632*10**(-9),z=0.1): """ pupil: Exit pupil diameter z: Distance from exit pupil to image plane r: pupil radius, in unit of lambda """ pupil = l1 = 200 # exit pupil sample points x = __np__.linspace(-r, r, l1) [X,Y] = __np__.meshgrid(x,x) Z = __interferometer__.__zernikecartesian__(self.__coefficients__,X,Y) for i in range(len(Z)): for j in range(len(Z)): if x[i]**2+x[j]**2>r**2: Z[i][j] = 0 d = 400 # background A = __np__.zeros([d,d]) A[d//2-l1//2+1:d//2+l1//2+1,d//2-l1//2+1:d//2+l1//2+1] = Z axis_1 = d//pupil*r fig = __plt__.figure() # ax = fig.gca() # __plt__.imshow(A,extent=[-axis_1,axis_1,-axis_1,axis_1],cmap=__cm__.RdYlGn) # ax.set_xlabel('mm',fontsize=14) # __plt__.colorbar() # __plt__.show() abbe = __np__.exp(-1j*2*__np__.pi*A) for i in range(len(abbe)): for j in range(len(abbe)): if abbe[i][j]==1: abbe[i][j]=0 PSF = __fftshift__(__fft2__(__fftshift__(abbe)))**2 PSF = PSF/PSF.max() return PSF
Example 12
Project: opticspy Author: Sterncat File: zernike.py License: MIT License | 5 votes |
def otf(self,r=1,lambda_1=632*10**(-9),z=0.1): PSF = self.__psfcaculator__(r=r,lambda_1=lambda_1,z=z) OTF = __fftshift__(__fft2__(PSF)) return 0
Example 13
Project: ProxImaL Author: comp-imaging File: utils.py License: MIT License | 5 votes |
def fftd(I, dims=None): # Compute fft if dims is None: X = fftn(I) elif dims == 2: X = fft2(I, axes=(0, 1)) else: X = fftn(I, axes=tuple(range(dims))) return X
Example 14
Project: ray-optics Author: mjhoptics File: analyses.py License: BSD 3-Clause "New" or "Revised" License | 5 votes |
def calc_psf(wavefront, ndim, maxdim): """Calculate the point spread function of wavefront W. Args: wavefront: ndim x ndim Numpy array of wavefront errors. No data condition is indicated by nan ndim: The sampling across the wavefront maxdim: The total width of the sampling grid Returns: AP, the PSF of the input wavefront """ maxdim_by_2 = maxdim//2 W = np.zeros([maxdim, maxdim]) nd2 = ndim//2 W[maxdim_by_2-(nd2-1):maxdim_by_2+(nd2+1), maxdim_by_2-(nd2-1):maxdim_by_2+(nd2+1)] = np.nan_to_num(wavefront) phase = np.exp(1j*2*np.pi*W) for i in range(len(phase)): for j in range(len(phase)): if phase[i][j] == 1: phase[i][j] = 0 AP = abs(fftshift(fft2(fftshift(phase))))**2 AP_max = np.nanmax(AP) AP = AP/AP_max return AP
Example 15
Project: picasso Author: jungmannlab File: imageprocess.py License: 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 16
Project: tierpsy-tracker Author: ver228 File: helper.py License: 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 17
Project: game-of-life Author: thearn File: lib.py License: 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 18
Project: odl Author: odlgroup File: shearlab_operator.py License: 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 19
Project: odl Author: odlgroup File: shearlab_operator.py License: 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 20
Project: odl Author: odlgroup File: shearlab_operator.py License: 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 21
Project: odl Author: odlgroup File: shearlab_operator.py License: 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 22
Project: pyoptools Author: cihologramas File: gs.py License: 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 23
Project: pyoptools Author: cihologramas File: gs.py License: 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