r3_label_to_region — 2D region op

• Data kinds: region → region

• Call: fullseye.apply(img, "r3_label_to_region", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

• HALCON equivalent: label_to_region (the HALCON reference is a useful guide to its meaning and parameters)

Usage

Extracts only the pixels with one specific gray value (label) from a label image (equivalent to HALCON `label_to_region`).

> The detailed description below is the original text — the summary and the headings are translated.

入力を 3 桁に丸めた上で 0 より大きい値をラベルとみなし、昇順に並べた`round(a * (ラベル数-1)) 番目のラベルを選んで、その値を持つ画素を領域として返す。b` は未使用。単純な 0/1 マスクはラベルが 1 つしか無いので常にその前景が返る。

Detailed usage guide

• gallery2d_region family guide

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• gallery2d_region — py -3.11 examples/gallery2d_region.py

Ops the type connects to (they accept region as input)

identity · reg_erode · reg_dilate · reg_open · reg_close · fill_holes · select_largest · remove_small

Same category (region)

reg_erode · reg_dilate · reg_open · reg_close · fill_holes · select_largest · remove_small · invert_region

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

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