edges op• Data kinds: color → image
• Call: fullseye.apply(img, "edges_color", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: edges_color (the HALCON reference is a useful guide to its meaning and parameters)
*The figure is the real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*
Detects color edge strength. Claimed to correspond to HALCON's `edges_color` (extracts color edges with a Canny/Deriche/Shen filter), but the implementation is fixed to Di Zenzo's multichannel gradient method rather than being filter-selectable.
> The detailed description below is the original text — the summary and the headings are translated.
各チャンネルに Sobel 勾配 (gx, gy) をかけ、勾配テンソル
`[[gxx, gxy], [gxy, gyy]]`（gxx=Σgx², gyy=Σgy², gxy=Σgx·gy）の最大
固有値を画素ごとに求め、その平方根をエッジ強度として最大値で正規化する。
a, b は未使用（HALCON 側にあるフィルタ種別・しきい値の選択はできない）。
• gallery2d_edges family guide
• 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.
The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.
cfa_to_rgb 0.50 0.50 edges_color 0.40 0.50
▸ Load this pipeline · Load & run
• gallery2d_edges — py -3.11 examples/gallery2d_edges.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
edges)sobel_mag · prewitt_mag · roberts_mag · dog · grad_dir · log · corner_response · sk_scharr
*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.