edges_sub_pix — 2D `contour` op

• Data kinds: image → contour

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

• HALCON equivalent: edges_sub_pix (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.

サブピクセル精度のエッジ点抽出。勾配とその法線方向(``gradient_

normals`)を求め、しきい値(0.15+0.5*a`)を超える画素を連結成分化した

後、放物線当てはめで各点をサブピクセル位置へ精密化する(``subpixel_

refine_edges`、ops` 側の同名 op と共有する実装 ―― 2026-09-02 修正で

真の意味でサブピクセルになった。旧実装は整数画素座標をそのまま返して

いた)。HALCON の `edges_sub_pix`（Extract sub-pixel precise edges using

Deriche, Lanser, Shen, or Canny filters.）に相当。

`a がエッジ強度のしきい値を振る。b` は未使用。

Detailed usage guide

• gallery2d_contour_measure 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_contour_measure — py -3.11 examples/gallery2d_contour_measure.py

• quickstart — py -3.11 examples/quickstart.py

Ops the type connects to (they accept `contour` as input)

identity · select_contours · smooth_contours · fit_line_contours · contours_to_region · count_contours · total_length · select_contours_xld

Same category (`contour`)

select_contours · smooth_contours · fit_line_contours · contours_to_region · sk_find_contours · lines_gauss · select_contours_xld · smooth_contours_xld

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

edges_sub_pix — 2D contour op