ct_scan op• Data kinds: projstack × ctgeometry → voxel
• Call: import fullseye as fs; fs.ledger.fdk_reconstruct(projections, geometry, filter_name='ramp', cutoff=1.0, device='auto', allow_incomplete=False) (to call the implementation directly, import ctscan; ctscan.fdk_reconstruct(projections, geometry, filter_name='ramp', cutoff=1.0, device='auto', allow_incomplete=False); from the registry, opstomography.get("fdk_reconstruct"))
• GPU: none (CPU reference implementation only)
Filtered back-projection for every scan with a formula: FDK and its relatives.
The Feldkamp-Davis-Kress steps, on one code path: weight each sample by the cosine of its ray and by the scan's redundancy, ramp-filter along the detector rows, then back-project with the (DSO / U)^2 weight. A fan is one row, a short scan takes Parker's weight, an offset detector Wang's, a helix a row window normalised per voxel, laminography a sin(tilt) scale, and a parallel beam has no divergence weight. The equiangular detector takes the (gamma / sin gamma)^2 kernel.
A scan with no formula, or an arc too short to determine the object, is refused and named: use sirt_reconstruct or tv_reconstruct.
:param projections: (view, V, U) line integrals. :param geometry: dict from ct_scan_geometry. :param filter_name: one of tomography.FILTERS except "none". :param cutoff: fraction of Nyquist to keep, (0, 1]. :param device: "auto", "cpu" or "cuda". :param allow_incomplete: reconstruct an arc under the minimum anyway. The result
is missing a wedge of the object and the density reads low.
:returns: (Z, Y, X) float attenuation volume. :raises ValueError: on a shape that disagrees with the geometry, a tomosynthesis
scan, or an incomplete arc. Empty input (projections with 0 elements) raises
ValueError.
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• ct_scan_modes — py -3.11 examples/ct_scan_modes.py
voxel as input)radon_volume · ct_forward_project
ct_scan)ct_scan_geometry · shepp_logan_3d · ellipsoid_phantom · ellipsoid_projections · ct_forward_project · ct_adjoint_project · sirt_reconstruct · os_sart_reconstruct
*Provenance: ctscan.py — TOMOGRAPHY operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.