canny — 2D segmentation op

• Data kinds: image → region

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

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

Usage

Simplified Canny-style edge detection (returns a region). Mapped to HALCON's `edges_image` (Extract edges using Deriche, Lanser, Shen, or Canny filters.), but this is a simplified version (an approximation) that does not perform non-maximum suppression or hysteresis thresholding.

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

`a が事前平滑化のガウシアン σ を 0.5〜2.0 に、b がしきい値を 0.1〜0.6 に振る。ガウシアンでぼかした画像に Sobel 勾配強度を掛け、正規化した値を b` で二値化するだけ——本家 Canny の細線化（1画素幅への収束）は無いため、エッジは本来の Canny より太く、複数画素にまたがって残る。

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 · adaptive_gauss_thresh · sk_otsu · sk_li · sk_yen · sk_sauvola · sk_niblack

*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.