Composable Filters#

Composable filters in pytme are inspired by the similarly named Compose operation used in deep learning frameworks. Composable filters are an explicit solution to defining complex filtering procedures and can be lazily evaluated.

To demonstrate the use of composable filters, let’s walk through a basic example showcasing how to combine BandPassReconstructed and WedgeReconstructed

import numpy as np
from tme.filters import Compose, BandPassReconstructed, WedgeReconstructed

sampling_rate = (5,5,5)           # Sampling rate, typically Å/voxel

# Setup bandpass filter
bandpass = BandPassReconstructed(
    lowpass=30,                   # Resolution to lowpass filter to
    highpass=5,                   # Resolution to highpass filter to
    sampling_rate=sampling_rate   # Required to translate cutoffs
)

# Setup wege mask
wedge = WedgeReconstructed(
    angles=[60, 60],              # Start, stop tilt angle
    opening_axis=2,               # Wedge is open in z-axis
    tilt_axis=0,                  # Sample is tilted over x-axis
    create_continuous_wedge=True, # Include all angles from -60 to 60
)

# Combine bandpass and wedge mask into a single filter
composed_filter = Compose([bandpass, wedge])

data_shape = (50,50,50)
filter_mask = composed_filter(
   shape=data_shape, return_real_fourier=False
)["data"]

# Apply the filter mask
data = np.random.rand(*data_shape)
data_filtered = np.fft.ifftn(np.fft.fftn(data * filter_mask)).real

Specification#

ComposableFilter serves as specification for new composable filters.

ComposableFilter

Base class for composable filters.

Aggregator#

Compose allows for combining the operations described by multiple objects of type ComposableFilter.

Compose

Compose a series of filters.

Frequency Filters#

`BandPass`	Generate per-tilt Bandpass filter.
`BandPassReconstructed`	Generate Bandpass filter for reconstructions.
`LinearWhiteningFilter`	Generate Fourier whitening filters.

Cryo-EM Filters#

`CTF`	Generate per-tilt contrast transfer function filter.
`CTFReconstructed`	Generate CTF filter for reconstructions.
`Wedge`	Create per-tilt wedge mask for tomographic data.
`WedgeReconstructed`	Create wedge mask for tomographic reconstructions.

Reconstruction#

ReconstructFromTilt

Place Fourier transforms of d-dimensional inputs into a d+1-dimensional array aking of weighted backprojection using direct fourier inversion.