"""Contains basic functions for analyzing the results of reconstructions The functions in this module are designed to work either with pytorch tensors or numpy arrays, so they can be used either directly after reconstructions on the attributes of the models themselves, or after-the-fact once the data has been stored in numpy arrays. """ from __future__ import division, print_function import torch as t import numpy as np from CDTools.tools import cmath from CDTools.tools import image_processing as ip from scipy import fftpack __all__ = ['orthogonalize_probes','standardize', 'synthesize_reconstructions', 'calc_consistency_prtf', 'calc_deconvolved_cross_correlation', 'calc_frc'] from matplotlib import pyplot as plt def orthogonalize_probes(probes): """Orthogonalizes a set of incoherently mixing probes The strategy is to define a reduced orthogonal basis that spans all of the retrieved probes, and then build the density matrix defined by the probes in that basis. After diagonalization, the eigenvectors can be recast into the original basis and returned Parameters ---------- probes : array An l x n x m complex array representing a stack of probes Returns ------- ortho_probes: array An l x n x m complex array representing a stack of probes """ try: probes = cmath.torch_to_complex(probes.detach().cpu()) send_to_torch = True except: send_to_torch = False bases = [] coefficients = np.zeros((probes.shape[0],probes.shape[0]), dtype=np.complex64) for i, probe in enumerate(probes): ortho_probe = np.copy(probe) for j, basis in enumerate(bases): coefficients[j,i] = np.sum(basis.conj()*ortho_probe) ortho_probe -= basis * coefficients[j,i] coefficients[i,i] = np.sqrt(np.sum(np.abs(ortho_probe)**2)) bases.append(ortho_probe / coefficients[i,i]) density_mat = coefficients.dot(np.conj(coefficients).transpose()) eigvals, eigvecs = np.linalg.eigh(density_mat) ortho_probes = [] for i in range(len(eigvals)): coefficients = np.sqrt(eigvals[i]) * eigvecs[:,i] probe = np.zeros(bases[0].shape, dtype=np.complex64) for coefficient, basis in zip(coefficients, bases): probe += basis * coefficient ortho_probes.append(probe) if send_to_torch: return cmath.complex_to_torch(np.stack(ortho_probes[::-1])) else: return np.stack(ortho_probes[::-1]) def standardize(probe, obj, obj_slice=None, correct_ramp=False): """Standardizes a probe and object to prepare them for comparison There are a number of ambiguities in the definition of a ptychographic reconstruction. This function makes an explicit choice for each ambiguity to allow comparisons between independent reconstructions without confusing these ambiguities for real differences between the reconstructions. The ambiguities and standardizations are: 1) a. Probe and object can be scaled inversely to one another b. So we set the probe intensity to an average per-pixel value of 1 2) a. The probe and object can aquire equal and opposite phase ramps b. So we set the centroid of the FFT of the probe to zero frequency 3) a. The probe and object can each acquire an arbitrary overall phase b. So we set the phase of the sum of all values of both the probe and object to 0 When dealing with the properties of the object, a slice is used by default as the edges of the object often are dominated by unphysical noise. The default slice is from 3/8 to 5/8 of the way across. If the probe is actually a stack of incoherently mixing probes, then the dominant probe mode (assumed to be the first in the list) is used, but all the probes are updated with the same factors. Parameters ---------- probe : array A complex array storing a retrieved probe or stack of incoherently mixed probes obj : array A complex array storing a retrieved probe obj_slice : slice Optional, a slice to take from the object for calculating normalizations correct_ramp : bool Default False, whether to correct for the relative phase ramps Returns ------- standardized_probe : array The standardized probe standardized_obj : array The standardized object """ # First, we normalize the probe intensity to a fixed value. probe_np = False if isinstance(probe, np.ndarray): probe = cmath.complex_to_torch(probe).to(t.float32) probe_np = True obj_np = False if isinstance(obj, np.ndarray): obj = cmath.complex_to_torch(obj).to(t.float32) obj_np = True # If this is a single probe and not a stack of probes if len(probe.shape) == 3: probe = probe[None,...] single_probe = True else: single_probe = False normalization = t.sqrt(t.sum(cmath.cabssq(probe[0])) / (len(probe[0].view(-1))/2)) probe = probe / normalization obj = obj * normalization # Default slice of the object to use for alignment, etc. if obj_slice is None: obj_slice = np.s_[(obj.shape[0]//8)*3:(obj.shape[0]//8)*5, (obj.shape[1]//8)*3:(obj.shape[1]//8)*5] if correct_ramp: # Need to check if this is actually working and, if not, why not center_freq = ip.centroid(cmath.cabssq(cmath.fftshift(t.fft(probe[0],2)))) center_freq -= (t.tensor(probe[0].shape[:-1]) // 2).to(t.float32) center_freq /= t.tensor(probe[0].shape[:-1]).to(t.float32) Is, Js = np.mgrid[:probe[0].shape[0],:probe[0].shape[1]] probe_phase_ramp = cmath.expi(2 * np.pi * (center_freq[0] * t.tensor(Is).to(t.float32) + center_freq[1] * t.tensor(Js).to(t.float32))) probe = cmath.cmult(probe, cmath.cconj(probe_phase_ramp)) Is, Js = np.mgrid[:obj.shape[0],:obj.shape[1]] obj_phase_ramp = cmath.expi(2*np.pi * (center_freq[0] * t.tensor(Is).to(t.float32) + center_freq[1] * t.tensor(Js).to(t.float32))) obj = cmath.cmult(obj, obj_phase_ramp) # Then, we set them to consistent absolute phases obj_angle = cmath.cphase(t.sum(obj[obj_slice],dim=(0,1))) obj = cmath.cmult(obj, cmath.expi(-obj_angle)) for i in range(probe.shape[0]): probe_angle = cmath.cphase(t.sum(probe[i],dim=(0,1))) probe[i] = cmath.cmult(probe[i], cmath.expi(-probe_angle)) if single_probe: probe = probe[0] if probe_np: probe = cmath.torch_to_complex(probe.detach().cpu()) if obj_np: obj = cmath.torch_to_complex(obj.detach().cpu()) return probe, obj def synthesize_reconstructions(probes, objects, use_probe=False, obj_slice=None, correct_ramp=False): """Takes a collection of reconstructions and outputs a single synthesized probe and object The function first standardizes the sets of probes and objects using the standardize function, passing through the relevant options. Then it calculates the closest overlap of subsequent frames to subpixel precision and uses a sinc interpolation to shift all the probes and objects to a common frame. Then the images are summed. Parameters ---------- probes : list(array) A list of probes or stacks of probe modes objects : list(array) A list of objects use_probe : bool Default False, whether to use the probe or object for alignment obj_slice : slice Optional, A slice of the object to use for alignment and normalization correct_ramp : bool Default False, whether to correct for a relative phase ramp in the probe and object Returns ------- synth_probe : array The synthesized probe synth_obj : array The synthesized object obj_stack : list(array) A list of standardized objects, for further processing """ probe_np = False if isinstance(probes[0], np.ndarray): probes = [cmath.complex_to_torch(probe).to(t.float32) for probe in probes] probe_np = True obj_np = False if isinstance(objects[0], np.ndarray): objects = [cmath.complex_to_torch(obj).to(t.float32) for obj in objects] obj_np = True obj_shape = np.min(np.array([obj.shape[:-1] for obj in objects]),axis=0) objects = [obj[:obj_shape[0],:obj_shape[1]] for obj in objects] if obj_slice is None: obj_slice = np.s_[(objects[0].shape[0]//8)*3:(objects[0].shape[0]//8)*5, (objects[0].shape[1]//8)*3:(objects[0].shape[1]//8)*5] synth_probe, synth_obj = standardize(probes[0].clone(), objects[0].clone(), obj_slice=obj_slice,correct_ramp=correct_ramp) obj_stack = [synth_obj] for i, (probe, obj) in enumerate(zip(probes[1:],objects[1:])): probe, obj = standardize(probe.clone(), obj.clone(), obj_slice=obj_slice,correct_ramp=correct_ramp) if use_probe: shift = ip.find_shift(synth_probe[0],probe[0], resolution=50) else: shift = ip.find_shift(synth_obj[obj_slice],obj[obj_slice], resolution=50) obj = ip.sinc_subpixel_shift(obj,np.array(shift)) if len(probe.shape) == 4: probe = t.stack([ip.sinc_subpixel_shift(p,tuple(shift)) for p in probe],dim=0) else: probe = ip.sinc_subpixel_shift(probe,tuple(shift)) synth_probe = synth_probe + probe synth_obj = synth_obj + obj obj_stack.append(obj) # If there only was one image try: i except: i = -1 if probe_np: synth_probe = cmath.torch_to_complex(synth_probe) if obj_np: synth_obj = cmath.torch_to_complex(synth_obj) obj_stack = [cmath.torch_to_complex(obj) for obj in obj_stack] return synth_probe/(i+2), synth_obj/(i+2), obj_stack def calc_consistency_prtf(synth_obj, objects, basis, obj_slice=None,nbins=None): """Calculates a PRTF between each the individual objects and a synthesized one The consistency PRTF at any given spatial frequency is defined as the ratio between the intensity of any given reconstruction and the intensity of a synthesized or averaged reconstruction at that spatial frequency. Typically, the PRTF is averaged over spatial frequencies with the same magnitude. Parameters ---------- synth_obj : array The synthesized object in the numerator of the PRTF objects : list(array) A list of objects or diffraction patterns for the denomenator of the PRTF basis : array The basis for the reconstruction array to allow output in physical unit obj_slice : slice Optional, a slice of the objects to use for calculating the PRTF nbins : int Optional, number of bins to use in the histogram. Defaults to a sensible value Returns ------- freqs : array The frequencies for the PRTF PRTF : array The values of the PRTF """ obj_np = False if isinstance(objects[0], np.ndarray): objects = [cmath.complex_to_torch(obj).to(t.float32) for obj in objects] obj_np = True if isinstance(synth_obj, np.ndarray): synth_obj = cmath.complex_to_torch(synth_obj).to(t.float32) if isinstance(basis, t.Tensor): basis = basis.detach().cpu().numpy() if obj_slice is None: obj_slice = np.s_[(objects[0].shape[0]//8)*3:(objects[0].shape[0]//8)*5, (objects[0].shape[1]//8)*3:(objects[0].shape[1]//8)*5] if nbins is None: nbins = np.max(synth_obj[obj_slice].shape) // 4 synth_fft = cmath.cabssq(cmath.fftshift(t.fft(synth_obj[obj_slice],2))).numpy() di = np.linalg.norm(basis[:,0]) dj = np.linalg.norm(basis[:,1]) i_freqs = fftpack.fftshift(fftpack.fftfreq(synth_fft.shape[0],d=di)) j_freqs = fftpack.fftshift(fftpack.fftfreq(synth_fft.shape[1],d=dj)) Js,Is = np.meshgrid(j_freqs,i_freqs) Rs = np.sqrt(Is**2+Js**2) synth_ints, bins = np.histogram(Rs,bins=nbins,weights=synth_fft) prtfs = [] for obj in objects: obj = obj[obj_slice] single_fft = cmath.cabssq(cmath.fftshift(t.fft(obj,2))).numpy() single_ints, bins = np.histogram(Rs,bins=nbins,weights=single_fft) prtfs.append(synth_ints/single_ints) prtf = np.mean(prtfs,axis=0) if not obj_np: bins = t.Tensor(bins) prtf = t.Tensor(prtf) return bins[:-1], prtf def calc_deconvolved_cross_correlation(im1, im2, im_slice=None): """Calculates a cross-correlation between two images with their autocorrelations deconvolved. This is formally defined as the inverse Fourier transform of the normalized product of the Fourier transforms of the two images. It results in a kernel, whose characteristic size is related to the exactness of the possible alignment between the two images, on top of a random background Parameters ---------- im1 : array The first image, as a complex or real valued array im2 : array The first image, as a complex or real valued array im_slice : slice Default is from 3/8 to 5/8 across the image, a slice to use in the processing. Returns ------- corr : array The complex-valued deconvolved cross-correlation, in real space """ im_np = False if isinstance(im1, np.ndarray): im1 = cmath.complex_to_torch(im1) im_np = True if isinstance(im2, np.ndarray): im2 = cmath.complex_to_torch(im2) im_np = True # If last dimension is not 2, then convert to a complex tensor now if im1.shape[-1] != 2: im1 = t.stack((im1,t.zeros_like(im1)),dim=-1) if im2.shape[-1] != 2: im2 = t.stack((im2,t.zeros_like(im2)),dim=-1) if im_slice is None: im_slice = np.s_[(im1.shape[0]//8)*3:(im1.shape[0]//8)*5, (im1.shape[1]//8)*3:(im1.shape[1]//8)*5] cor_fft = cmath.cmult(t.fft(im1[im_slice],2), cmath.cconj(t.fft(im2[im_slice],2))) # Not sure if this is more or less stable than just the correlation # maximum - requires some testing cor = t.ifft(cor_fft / cmath.cabs(cor_fft)[:,:,None],2) if im_np: cor = cmath.torch_to_complex(cor) return cor def calc_frc(im1, im2, basis, im_slice=None, nbins=None, snr=1.): """Calculates a Fourier ring correlation between two images This function requires an input of a basis to allow for FRC calculations to be related to physical units. Like other analysis functions, this can take input in numpy or pytorch, and will return output in the respective format. Parameters ---------- im1 : array The first image, a complex or real valued array im2 : array The first image, a complex or real valued array basis : array The basis for the images, defined as is standard for datasets im_slice : slice Default is from 3/8 to 5/8 across the image, a slice to use in the processing. nbins : int Number of bins to break the FRC up into snr : float The signal to noise ratio (for the combined information in both images) to return a threshold curve for. Returns ------- freqs : array The frequencies associated with each FRC value FRC : array The FRC values threshold : array The threshold curve for comparison """ im_np = False if isinstance(im1, np.ndarray): im1 = cmath.complex_to_torch(im1) im_np = True if isinstance(im2, np.ndarray): im2 = cmath.complex_to_torch(im2) im_np = True if isinstance(basis, np.ndarray): basis = t.tensor(basis) # If last dimension is not 2, then convert to a complex tensor now if im1.shape[-1] != 2: im1 = t.stack((im1,t.zeros_like(im1)),dim=-1) if im2.shape[-1] != 2: im2 = t.stack((im2,t.zeros_like(im2)),dim=-1) if im_slice is None: im_slice = np.s_[(im1.shape[0]//8)*3:(im1.shape[0]//8)*5, (im1.shape[1]//8)*3:(im1.shape[1]//8)*5] if nbins is None: nbins = np.max(im1[im_slice].shape) // 4 cor_fft = cmath.cmult(cmath.fftshift(t.fft(im1[im_slice],2)), cmath.fftshift(cmath.cconj(t.fft(im2[im_slice],2)))) F1 = cmath.cabs(cmath.fftshift(t.fft(im1[im_slice],2)))**2 F2 = cmath.cabs(cmath.fftshift(t.fft(im2[im_slice],2)))**2 di = np.linalg.norm(basis[:,0]) dj = np.linalg.norm(basis[:,1]) i_freqs = fftpack.fftshift(fftpack.fftfreq(cor_fft.shape[0],d=di)) j_freqs = fftpack.fftshift(fftpack.fftfreq(cor_fft.shape[1],d=dj)) Js,Is = np.meshgrid(j_freqs,i_freqs) Rs = np.sqrt(Is**2+Js**2) numerator, bins = np.histogram(Rs,bins=nbins,weights=cmath.torch_to_complex(cor_fft)) denominator_F1, bins = np.histogram(Rs,bins=nbins,weights=F1.detach().cpu().numpy()) denominator_F2, bins = np.histogram(Rs,bins=nbins,weights=F2.detach().cpu().numpy()) n_pix, bins = np.histogram(Rs,bins=nbins) frc = np.abs(numerator / np.sqrt(denominator_F1*denominator_F2)) # This moves from combined-image SNR to single-image SNR snr /= 2 threshold = (snr + (2 * snr + 1) / np.sqrt(n_pix)) / \ (1 + snr + (2 * np.sqrt(snr)) / np.sqrt(n_pix)) if not im_np: bins = t.tensor(bins) frc = t.tensor(frc) threshold = t.tensor(threshold) return bins[:-1], frc, threshold