ellipse_phantom — TOMOGRAPHY `forward` op

• 数据种类:无 → image2d(仅由参数决定的算子 —— 不接受图像或数据输入)

• 调用:import tomography; tomography.ellipse_phantom(size=256, ellipses=None, supersample=4)(或 opstomography.get("ellipse_phantom"))

把若干均匀椭圆之和栅格化到 *size* x *size* 的切片上。

> 以下的详细说明为原文 —— 摘要与标题已翻译。

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.

• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。

• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。

• 算法的正典(作者・年份)与用途见上面的族使用指南。

• ct_reconstruction — py -3.11 examples/ct_reconstruction.py

• tomography_reconstruct — py -3.11 examples/tomography_reconstruct.py

*Provenance: tomography.py — TOMOGRAPHY 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*

ellipse_phantom — TOMOGRAPHY forward op