contour op• Data kinds: contour → contour
• Call: fullseye.apply(img, "fit_line_contours", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: fit_line_contour_xld (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).*
Approximates each XLD contour with a single straight line. Equivalent to HALCON's `fit_line_contour_xld` (Approximate XLD contours by line segments.).
> The detailed description below is the original text — the summary and the headings are translated.
`a, b` は未使用。輪郭点群の重心を通り、SVD(特異値分解)で求めた第一主成分方向を直線の向きとして採用し(全点との距離二乗和を最小化する直線)、元の点群の射影範囲に等間隔に打ち直した点列に置き換える。HALCON 版は折れ線(複数線分)に分割できるが、この実装は輪郭全体を 1 本の直線にする点が異なる。点が 2 点未満の輪郭はそのまま返す。
• gallery2d_contour_measure 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.
threshold 0.50 0.50 sk_find_contours 0.50 0.50 fit_line_contours 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_contour_measure — py -3.11 examples/gallery2d_contour_measure.py
contour as input)identity · select_contours · smooth_contours · contours_to_region · count_contours · total_length · select_contours_xld · smooth_contours_xld
contour)select_contours · smooth_contours · contours_to_region · sk_find_contours · edges_sub_pix · 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).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.