Backend

Cross-correlate a stack of particle images against a template.

Here, the argument 'particle_stack_dft' is a set of RFFT-ed particle images with necessary filtering already applied. The zeroth dimension corresponds to unique particles.

Parameters:

• particle_stack_dft (Tensor) –

  The stack of particle real-Fourier transformed and un-fftshifted images. Shape of (N, H, W).

• template_dft (Tensor) –

  The template volume to extract central slices from. Real-Fourier transformed and fftshifted.

• rotation_matrices (Tensor) –

  The orientations of the particles to take the Fourier slices of, as a long list of rotation matrices. Shape of (N, 3, 3).

• projective_filters (Tensor) –

  Projective filters to apply to each Fourier slice particle. Shape of (N, h, w).

• mode (Literal['valid', 'same'], default: 'valid' ) –

  Correlation mode to use, by default "valid". If "valid", the output will be the valid cross-correlation of the inputs. If "same", the output will be the same shape as the input particle stack.

• batch_size (int, default: 1024 ) –

  The number of particle images to cross-correlate at once. Default is 1024. Larger sizes will consume more memory. If -1, then the entire stack will be cross-correlated at once.

• mag_matrix (Tensor | None, default: None ) –

  Anisotropic magnification matrix of shape (2, 2). If None, no magnification transform is applied. Default is None.

Returns:

• Tensor –

  The cross-correlation of the particle stack with the template. Shape will depend on the mode used. If "valid", the output will be (N, H-h+1, W-w+1). If "same", the output will be (N, H, W).

Raises:

• ValueError –

  If the mode is not "valid" or "same".