vol_equalize — 3D gray op

• Datenarten: voxel → voxel

• Aufruf: import fullseye as fs; fs.ledger.vol_equalize(vol, nbins=256, mask=None) (die Implementierung direkt: import volgray; volgray.vol_equalize(vol, nbins=256, mask=None); aus dem Register: ops3d.get("vol_equalize"))

Verwendung

Histogrammangleichung eines Volumens (HALCON equ_histo_image).

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

Builds an *nbins*-bin histogram over the volume's [min, max] range, takes its cumulative distribution as a monotone LUT, and maps every voxel through it — the output lives in (0, 1] and its histogram is (approximately) flat. With *mask* (thresholded at > 0.5, the volops convention) the histogram is computed from the masked voxels only while the LUT is applied to the whole volume — exactly the HALCON reduce_domain + equ_histo_image domain behaviour, and the right tool when a dominant background (e.g. air around a CT subject) would otherwise swallow the whole dynamic range.

A constant volume is returned unchanged — normalising a flat volume would amplify floating-point dust into full-scale garbage (fail-honest, not fail-loud; see the module docstring).

Parameters

vol : array_like, shape (D, H, W)

Input volume (coerced to float64; NaN/Inf rejected).

nbins : int

Histogram bins, >= 2. More bins = finer LUT (the mapping is

piecewise-constant per bin — an approximation, documented above).

mask : array_like, shape (D, H, W), optional

Histogram domain. Must match *vol*'s shape and select at least one

voxel (an empty domain has no histogram — fail-closed).

Returns

ndarray, shape (D, H, W), float64

The equalised volume in [0, 1] (constant input: the input itself).

Raises

ValueError

Non-3-D / non-finite input, nbins < 2, a mask shape mismatch, or

an empty mask.

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)

• gray_window_level — py -3.11 examples_3d/gray_window_level.py

Typkompatible Folge-Operatoren (nehmen voxel als Eingabe)

voxel_to_mips · voxel_to_mesh · signed_distance_field · to_points · sobel3d · hessian3d · curvature_maps · edt_jfa

Gleiche Kategorie (gray)

vol_window_level · vol_gamma · vol_stretch


*Provenance: volgray.py — 3D 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.