sk_frangi — 2D `texture` op

• Data kinds: image → image

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

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

sk_frangi: 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

Frangi's tubular structure detection filter (vesselness filter). Detects elongated tubular structures such as blood vessels, wrinkles, or rivers from the eigenvalue ratios of the Hessian matrix.

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

HALCON の lines_gauss(Detect lines and their width.)に相当(近似。線の幅や XLD 輪郭は返さず、応答強度の画像のみを返す)。2026-08-30 に a, b を配線した: a はスケール範囲(`sigmas=range(1, 2+round(a*4)) —— 最大 σ を 1〜5 に振る。a=0.5 で旧来の固定範囲 range(1,4) とビット一致)、b は Frangi の blobness 感度 β を 0.15〜0.85 に振る(b=0.5 で skimage 既定の 0.5 と一致し、既定出力は変わらない)。既定で black_ridges=True`(明るい背景上の暗い管を検出する)ため、白い背景に黒い線が乗った画像でないと応答が弱く出る点に注意。

Detailed usage guide

• gallery2d_texture_freq 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.

sk_frangi 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_texture_freq — py -3.11 examples/gallery2d_texture_freq.py

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

identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter

Same category (`texture`)

std_filter · gabor · sk_meijering · sk_hessian · sk_gabor · sk_lbp · sk_entropy · sk_shape_index

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

sk_frangi — 2D texture op