lf_epi_slope — LIGHTFIELD `depth` op

• 데이터 종류: lightfield → image2d

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

사용법

EPI 선의 방향으로부터 화소별 기울기를 냅니다(구조 텐서, 1 패스).

> 아래 상세 설명은 원문입니다 —— 요약과 제목은 번역되어 있습니다.

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*.

자세한 사용 가이드

• lightfield_depth 패밀리 가이드

참고(샘플 데이터·문헌)

• 샘플 데이터 카탈로그(DL URL / 라이선스) —— 2-D 는 skimage.data(BSD/public)+ 합성, 3-D 는 실데이터 소스(Stanford/PDS 등)의 DL URL.

• 연산자의 내력·참고문헌 —— 이 연산자 족의 바탕이 된 연구/기법의 출처.

• 알고리즘의 정전(저자·연도)과 용도는 위의 패밀리 사용 가이드에 적혀 있습니다.

실행 가능한 예제(이 연산자를 실제로 호출하는 검증된 샘플)

• lightfield_depth — py -3.11 examples/lightfield_depth.py

타입이 이어지는 다음 연산자(`image2d` 를 입력으로 받는 것)

lf_from_mla · lf_disparity_to_depth · lf_all_in_focus

같은 카테고리(`depth`)

lf_depth_from_focus · lf_disparity_to_depth · lf_all_in_focus · lf_plenoptic_design

*Provenance: lightfield.py — LIGHTFIELD 연산자 레지스트리. 이 op 노트는 tools/opdocs.py md 가 자동 생성합니다(직접 편집하지 마세요).*

lf_epi_slope — LIGHTFIELD depth op

사용법