fullseye

sinogram_center_shift — TOMOGRAPHY geometry op

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

使い方

Re-centre a sinogram on its axis of rotation.

Shifts every projection by -shift_px along the detector axis with linear interpolation. With shift_px=None the shift is measured first by :func:sinogram_center_of_rotation, which makes this the one-call fix.

Round-trip on the Shepp-Logan phantom, shifting by d and back:

d        max |error|    relative to the peak line integral
1.00 px   0.0e+00        0.0e+00     (an integer shift is exact)
0.50 px   1.4e-01        1.2e-01
0.25 px   1.1e-01        9.2e-02

A fractional shift is not a small operation and this is the operator’s honest limitation: 12 % of the peak, on a phantom with sharp edges, from one round trip. Interpolation is a low-pass filter and the sinogram of an edge is not band-limited, so there is nothing to recover on the way back. Using a Fourier shift instead would trade this visible blur for invisible ringing at the detector edges, which is worse in the way that matters here. The consequence is in :func:sinogram_center_of_rotation’s table: an integer centre error is fully repairable, a half-pixel one is not.

:param sinogram: (n_angles, n_detectors). :param shift_px: axis offset in detector bins; None -> measure it. :param angles_deg: view angles, used only when shift_px is None. :returns: (n_angles, n_detectors) float64 sinogram. :raises ValueError: if |shift_px| is at or past half the detector width — past that the object has been shifted out of the field of view and what comes back is edge padding, which reconstructs as a plausible, empty slice.

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_apply · ring_artifact_remove · metal_trace_interpolate

同カテゴリ(geometry)

sinogram_center_of_rotation

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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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