artifact op• データ種: sinogram → sinogram
• 呼び出し: import tomography; tomography.beam_hardening_correct(sinogram, high_energy_fraction=0.5, attenuation_ratio=0.4, poly_coeffs=None, n_table=4096) (または opstomography.get("beam_hardening_correct"))
カッピングを戻す —— モデルの厳密な逆、または校正済み多項式で。
> 以下の詳細説明は原文のままです —— 要約と見出しは訳出済み。
Two routes, and the difference between them is what you are allowed to claim:
• Model inverse (default). :func:beam_hardening_apply is a monotone
scalar function of the line integral, so it has an exact inverse; this
builds it by interpolating the forward curve on *n_table* nodes. Round-trip
error on the disc phantom: 1.6e-08 absolute and 8.0e-09 relative to
the peak line integral — the table resolution and nothing else.
This is a *simulation* tool — it needs the same `w and k` the
hardening used, which on real data nobody has.
• Polynomial (*poly_coeffs*). `p_corr = c1 p + c2 p^2 + ...`, the
water-correction of every clinical scanner, whose coefficients come from
scanning a uniform water phantom and fitting for a flat reconstruction.
This is what applies to real data, and it is only as good as the assumption
that everything in the field of view attenuates like water.
The honest limitation is the same one every scanner has: the correction is
material-specific. A water calibration applied to a slice containing bone
or metal over-corrects the dense material and leaves dark bands between dense
objects, and nothing in the sinogram says which case you are in.
:param sinogram: `(n_angles, n_detectors)` hardened line integrals.
:param high_energy_fraction: *w* used by the forward model.
:param attenuation_ratio: *k* used by the forward model.
:param poly_coeffs: `(c1, c2, ...)`; when given, the polynomial route is
used and *w* / *k* are ignored.
:param n_table: nodes of the inverse table, `64 .. 1048576`.
:returns: `(n_angles, n_detectors)` float64 corrected sinogram.
:raises ValueError: as :func:beam_hardening_apply, plus an empty or
non-finite *poly_coeffs*.
• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。
• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。
• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。
• ct_reconstruction — py -3.11 examples/ct_reconstruction.py
sinogram を入力に取れる)backproject_sinogram · filtered_backprojection · sart_reconstruct · beam_hardening_apply · ring_artifact_apply · ring_artifact_remove · metal_trace_interpolate · sinogram_center_of_rotation
artifact)beam_hardening_apply · ring_artifact_apply · ring_artifact_remove · metal_trace_interpolate
*Provenance: tomography.py — TOMOGRAPHY operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.