lines_facet — 2D `contour` op

• Data kinds: image → contour

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

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

lines_facet: 入力 → 出力

*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).*

Usage

Detects line-like structures (ridges) and returns them as a contour (XLD contour). The implementation computes 'line-ness' using a Frangi filter (`skimage.filters.frangi, multiscale sigma=1..3 ridge enhancement), and outputs the pixel coordinates of connected components exceeding the threshold 0.1+0.4a` directly as a contour point sequence. b is unused.

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

HALCON の `lines_facet`（局所多項式近似=ファセットモデルで線を検出する演算）とは検出原理が異なる近似 —— facet モデルによるサブピクセル位置推定は行わず、Frangi 応答の二値化領域を輪郭化しているだけなので、座標はサブピクセル精度を持たない。

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.

Try it in Studio

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.

lines_facet 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_contour_measure — py -3.11 examples/gallery2d_contour_measure.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 · edges_sub_pix · lines_gauss · select_contours_xld

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

lines_facet — 2D contour op