typed op• 数据种类:lightfield → image
• 调用:fullseye.apply(img, "tb_lf_epi_slope", a=0.5, b=0.5)(2-D 的模型是一张图 + 两个标量旋钮 a,b∈[0,1])
*无图: 该算子以 lightfield 为输入。从图像开始的 Studio 程序无法到达该类型，请参见下方的可运行示例。*
根据极平面图像（EPI）直线方向得到的逐像素斜率（结构张量，单次计算）。
> 以下的详细说明为原文 —— 摘要与标题已翻译。
A scene point traces a straight line in the epipolar-plane image
(:func:lf_epi), so along that line the intensity is constant:
`E_u + s * E_x = 0`. Accumulating that constraint over the whole angular
grid and a `window x window` spatial neighbourhood gives the closed-form
least-squares slope `s = -(J_ux + J_vy) / (J_xx + J_yy)` with
`J_ab = sum(E_a * E_b)` — one pass over the light field, no sweep, both
the horizontal and vertical EPI directions pooled.
This estimator is biased, and the bias is the reason to also run
:func:lf_depth_from_focus. It is ordinary (not total) least squares on
finite differences, so it needs the EPI line to advance less than roughly
one texture correlation length per view. Measured 2026-09-01 on
5x5x64x64 synthetic fields, median over the interior: with texture
`sigma = 1.5 px, true +1.00 -> +1.0004, +0.50 -> +0.5285`,
`+1.50 -> +1.3018, +2.00 -> +1.4614; with sigma = 5.0` px the same
slopes give `+1.0003, +0.5029, +1.4827, +1.9482`. Integer
slopes on a wrapped field come back within 4e-4 and `s = 0` is exact;
`|s| > 1 is under-estimated, by 27% at s = 2` on the roughest texture.
Use it as a fast dense initialiser, not as the final word.
Returns `(slope_map, energy): the (H, W) slope map and the (H, W)`
gradient energy `J_xx + J_yy` that was the denominator. Pixels whose
energy is below *min_energy* have no measurable parallax (a flat patch
of sky); their slope is set to 0 and their energy reported as-is, so you
threshold on `energy` instead of being handed a plausible-looking number
divided by ~0.
Raises `ValueError`: *lf* not a valid light field, an angular/spatial
shape where *neither* EPI direction carries information (the horizontal EPI
needs `U >= 2 **and** W >= 2, the vertical needs V >= 2` and
`H >= 2`), an even or non-positive *window*, a non-positive *min_energy*.
Typed bridge of the lightfield op `lf_epi_slope into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. This op has no tunable parameter; a and b` are unused.
• 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。
• (暂无)
image 作为输入)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
typed)tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_angle_3points · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal
*Provenance: ops.py — 2D 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.