var_threshold — 2D `segmentation` op

• Data kinds: image → region

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

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

Usage

> This operator's description has not been translated yet. The original text follows as it is.

Sauvola の局所適応的二値化(`skimage.filters.threshold_sauvola`、

窓サイズ `2*int(a*6)+3`)。局所平均と局所標準偏差の両方を使ってしきい値

を決めるため、`dyn_threshold` より照明ムラや低コントラスト文書に強い。

HALCON の `var_threshold`（Threshold an image by local mean and standard

deviation analysis.）に相当する近似(定式化は似た発想だが Sauvola の式と

HALCON の式は係数が異なる ―― 同一の数値結果にはならない)。

`a が局所窓のサイズを振る。b` は未使用(Sauvola の k, r は skimage の

既定値に固定)。

Detailed usage guide

• gallery2d_segmentation 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_segmentation — py -3.11 examples/gallery2d_segmentation.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 (`segmentation`)

threshold · otsu · canny · adaptive_gauss_thresh · sk_otsu · sk_li · sk_yen · sk_sauvola

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

var_threshold — 2D segmentation op