fullseye

ring_artifact_apply — TOMOGRAPHY artifact op

• データ種: sinogram → sinogram
• 呼び出し: import fullseye as fs; fs.ledger.ring_artifact_apply(sinogram, gain_sigma=0.02, seed=0, offsets=None) (実装を直接呼ぶなら import tomography; tomography.ring_artifact_apply(sinogram, gain_sigma=0.02, seed=0, offsets=None)、台帳から引くなら opstomography.get("ring_artifact_apply"))

使い方

Give the detector a per-bin gain error — the source of ring artefacts.

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
• poc_battery_ct_degradation — py -3.11 examples/poc_battery_ct_degradation.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

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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.

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