fullseye

ellipse_phantom — TOMOGRAPHY forward op

• データ種: なし → image2d(引数だけで決まる op —— 画像やデータの入力を取らない)
• 呼び出し: import fullseye as fs; fs.ledger.ellipse_phantom(size=256, ellipses=None, supersample=4) (実装を直接呼ぶなら import tomography; tomography.ellipse_phantom(size=256, ellipses=None, supersample=4)、台帳から引くなら opstomography.get("ellipse_phantom"))

使い方

Rasterise a sum of uniform ellipses onto a size x size slice.

The default is :data:SHEPP_LOGAN. The normalised square [-1, 1]^2 maps onto the grid, so x = (col - (size-1)/2) / (size/2); the same mapping is used by :func:ellipse_sinogram, which is what makes the two comparable without a fudge factor.

supersample is the anti-aliasing factor: each pixel is the mean of supersample^2 sub-samples, so an edge pixel carries its true area fraction. This is not cosmetic — a hard 0/1 rasterisation projects to a sinogram that disagrees with the closed form by 0.276 % interior RMS of the peak, against 0.073 % anti-aliased (measured), and the difference is entirely the partial-volume edge.

:param size: side of the square grid, 2 .. 16384. :param ellipses: (N, 6) rows (x0, y0, a, b, phi_deg, rho) in normalised coordinates; None -> :data:SHEPP_LOGAN. :param supersample: anti-alias factor per axis, 1 .. 16. :returns: (size, size) float64 image; the Shepp-Logan default spans [0.0, 1.0]. :raises ValueError: on a non-int size, a degenerate ellipse, or a grid over :data:MAX_IMAGE_ELEMENTS.

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_ct_fidelity — py -3.11 examples/poc_ct_fidelity.py
• tomography_reconstruct — py -3.11 examples/tomography_reconstruct.py

型が繋がる次の op(image2d を入力に取れる)

radon_transform

同カテゴリ(forward)

ellipse_sinogram · radon_transform

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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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