ring_artifact_apply — TOMOGRAPHY artifact op

• データ種: sinogram → sinogram

• 呼び出し: import tomography; tomography.ring_artifact_apply(sinogram, gain_sigma=0.02, seed=0, offsets=None) (または opstomography.get("ring_artifact_apply"))

使い方

検出器にビンごとのゲイン誤差を与える —— リングアーチファクトの源。

> 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。

A detector bin whose gain is `g reports I = g I_true`, so after the

logarithm the line integral picks up a constant offset `-ln g` at that

bin, the same at every angle. Back-projecting a constant column smears it

around the rotation axis, and the reconstruction grows a ring at the radius

that bin's rays are tangent to. One bad pixel, one perfect circle.

The offsets are drawn once from `N(0, gain_sigma)` with a fixed *seed* and

applied to every row, because the whole point is that the error does not

vary with angle — that is what distinguishes a ring from noise, and what makes

:func:ring_artifact_remove possible.

:param sinogram: `(n_angles, n_detectors)`.

:param gain_sigma: standard deviation of the per-bin offset, `>= 0`.

:param seed: RNG seed; there is no `None` (determinism is a contract here).

:param offsets: explicit `(n_detectors,)` offsets; overrides the random draw.

:returns: `(n_angles, n_detectors)` float64 sinogram.

:raises ValueError: on a negative sigma, a non-int seed, or an *offsets* whose

length is not the detector count.

参考(サンプルデータ・文献)

• 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。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• ct_reconstruction — py -3.11 examples/ct_reconstruction.py

型が繋がる次の op(sinogram を入力に取れる)

backproject_sinogram · filtered_backprojection · sart_reconstruct · beam_hardening_apply · beam_hardening_correct · ring_artifact_remove · metal_trace_interpolate · sinogram_center_of_rotation

同カテゴリ(artifact)

beam_hardening_apply · beam_hardening_correct · 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.