cv_canny — 2D segmentation op

Data kinds: imageregion

Call: fullseye.apply(img, "cv_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

Canny edge detection (region variant, OpenCV implementation). Same algorithm as sk_canny, but the OpenCV version's API takes two thresholds directly rather than the sigma of Gaussian smoothing.

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

HALCON の edges_image に相当。実装は `cv2.Canny(_u8(v), threshold1=int(50+100*a), threshold2=int(100+150*b))` の結果を真偽値化したもの —— a は下側しきい値(弱いエッジの採用ライン)を 50〜150 に、b は上側しきい値(強いエッジの確定ライン)を 100〜250 に振る。a を大きく b を小さく振ると下側が上側を上回ることがあり、その場合の挙動は OpenCV の実装依存になる点に注意。

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_segmentationpy -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).*

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