f2_topographic — 2D edges op

• Data kinds: image → image

• Call: fullseye.apply(img, "f2_topographic", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

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

Usage

Haralick topographic primal sketch: classify every pixel from its gradient magnitude and the two Hessian eigenvalue signs into peak / pit / ridge / ravine / saddle / flat / hillside and emit the class as a gray code.

`a sets the derivative smoothing scale; b` sets the "flat gradient"

tolerance. Codes: flat=0.0, pit=0.14, ravine=0.30, saddle=0.45,

hillside=0.55, ridge=0.75, peak=1.0.

Detailed usage guide

• gallery2d_edges 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_edges — py -3.11 examples/gallery2d_edges.py

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

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

Same category (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.