forward op• 資料種類:無 → image2d(僅由參數決定的運算子 —— 不接受影像或資料輸入)
• 呼叫:import tomography; tomography.ellipse_phantom(size=256, ellipses=None, supersample=4)(或 opstomography.get("ellipse_phantom"))
把若干均勻橢圓之和柵格化到 *size* x *size* 的切片上。
> 以下的詳細說明為原文 —— 摘要與標題已翻譯。
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.
• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。
• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。
• 演算法的正典(作者・年份)與用途見上面的族使用指南。
• ct_reconstruction — py -3.11 examples/ct_reconstruction.py
• tomography_reconstruct — py -3.11 examples/tomography_reconstruct.py
image2d 作為輸入)forward)ellipse_sinogram · radon_transform
*Provenance: tomography.py — TOMOGRAPHY 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.