dual_threshold — 2D `segmentation` op

• Data kinds: image → region

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

• HALCON equivalent: dual_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.

符号つき画像向けのしきい値処理。中央値 0.5 を「ゼロ」とみなし、

`|x - 0.5| > 0.1+0.35*a` を満たす画素(0.5 から十分離れた画素)を前景と

する ―― 正負どちらの側にも対称に反応する。HALCON の `dual_threshold`

（Threshold operator for signed images.）に相当(HALCON は正負で別々の

しきい値を持てるが、ここでは 0.5 を中心とした対称な帯域に単純化)。

`a が除外帯域の半幅を振る。b は未使用。highpass_image` や

`bandpass_image` のような符号つき応答(0.5=ゼロ)の後段でよく使う。

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).*

dual_threshold — 2D segmentation op