tb_lf_depth_from_focus — 2D typed op

Datenarten: lightfieldimage

Aufruf: fullseye.apply(img, "tb_lf_depth_from_focus", a=0.5, b=0.5) (das 2-D-Modell ist ein Bild plus zwei skalare Regler a,b∈[0,1])

*Keine Abbildung: dieser Op nimmt lightfield als Eingabe. Ein Studio-Programm, das bei einem Bild beginnt, erreicht diesen Typ nicht — siehe die lauffähigen Beispiele unten.*

Verwendung

Pixelweise Steigung aus dem Schärfe-Maximum über den Refokus-Sweep.

> Die ausführliche Beschreibung unten ist der Originaltext — Zusammenfassung und Überschriften sind übersetzt.

Refocus at every slope in *slopes*, measure local sharpness (*measure*:

`laplacian` = summed modified Laplacian, the classical depth-from-focus

operator; `variance = local variance; gradient` = local gradient

energy) in a `window x window` neighbourhood, and take the slope at which

each pixel is sharpest. With `subpixel=True` (default) the peak is refined

by fitting a parabola through the winning sample and its two neighbours on a

uniformly spaced sweep — on a non-uniform sweep the refinement is

skipped rather than applied with the wrong spacing.

Unbiased where :func:lf_epi_slope is not: measured 2026-09-01 on a

5x5x64x64 synthetic field over a 121-point sweep from -3 to +3, the argmax

landed exactly on the true slope in 18 of 18 combinations (true slopes

0.0, +0.5, +1.0, +1.5, +2.0, -1.0 crossed with texture sigma 1.5 / 3.0 /

5.0 px), and the sub-pixel refinement left every one of them unmoved. Its

resolution, though, is whatever you put in *slopes* — it cannot see a plane

you never refocused on.

Returns `(slope_map, sharpness): the (H, W)` map of estimated slopes

(in px per angular step) and the `(H, W)` peak focus-measure value, which

is the honest confidence — a textureless pixel has no sharpness peak, gets

an essentially arbitrary slope, and its `sharpness` is ~0. Threshold on it

rather than trusting the map everywhere.

Raises `ValueError`: *lf* not a valid light field, *slopes* empty /

over :data:MAX_STACK_SLICES / over :data:MAX_STACK_ELEMENTS / containing

a non-finite or over-large value, an even or non-positive *window*, unknown

*measure* / *interp* / *edge*.

Typed bridge of the lightfield op `lf_depth_from_focus 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.

Referenzen (Beispieldaten, Literatur)

• Katalog der Beispieldaten (Download-URLs / Lizenzen) — 2-D nutzt skimage.data (BSD/Public Domain) plus synthetische Bilder, 3-D nennt Download-URLs echter Datenquellen (Stanford, PDS, …).

• Herkunft und Literatur der Operatoren — die Quellen der Forschung/Verfahren, auf denen diese Operatorfamilie beruht.

Ausführbare Beispiele (verifizierte Samples, die diesen Operator wirklich aufrufen)

• (noch keine)

Typkompatible Folge-Operatoren (nehmen image als Eingabe)

identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter

Gleiche Kategorie (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 Operator-Registry. Diese Notiz wird von tools/opdocs.py md erzeugt (nicht von Hand bearbeiten).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.