lf_epi_slope — LIGHTFIELD `depth` op

• 数据种类:lightfield → image2d

• 调用:import lightfield; lightfield.lf_epi_slope(lf, *, window=9, min_energy=1e-10)(或 opslightfield.get("lf_epi_slope"))

用法

由 EPI 线的方向得到逐像素斜率(结构张量,一趟完成)。

> 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*.

详细使用指南

• lightfield_depth 族使用指南

参考(示例数据・文献)

• 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。

可运行的示例(实际调用该算子并已验证的样例)

• lightfield_depth — py -3.11 examples/lightfield_depth.py

类型可衔接的下一个算子(可接受 `image2d` 作为输入)

lf_from_mla · lf_disparity_to_depth · lf_all_in_focus

同类别(`depth`)

lf_depth_from_focus · lf_disparity_to_depth · lf_all_in_focus · lf_plenoptic_design

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

lf_epi_slope — LIGHTFIELD depth op

用法