threshold op• Data kinds: image2d → table
• Call: import fullseye as fs; fs.ledger.threshold_triangle(image, *, nbins: 'int' = 256) -> 'Dict[str, object]' (to call the implementation directly, import seggraph; seggraph.threshold_triangle(image, *, nbins: 'int' = 256) -> 'Dict[str, object]'; from the registry, opssegmentation.get("threshold_triangle"))
Triangle method (Zack–Rogers–Latt 1977): the threshold is the bin (b, h_b) between the peak (b_p, h_p) and the end bin of the longer tail (b_e, 0) whose signed perpendicular distance from the line joining them is largest (below the line is positive). Returns: threshold (centre of that bin), mask = image > threshold, bin, distance (distance of each bin, nan outside the range). The zero height at the end point and the choice of tail follow the skimage / ImageJ convention (original paper to be confirmed) (threshold_triangle).
• halcon_segmentation family guide
• graph_hierarchy_and_thresholds — Segmentation from graph, hierarchy and threshold theorems — what is exact, and where the partition breaks down
• 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.
• poc_graph_hierarchy_segmentation — py -3.11 examples/poc_graph_hierarchy_segmentation.py
table as input)threshold)threshold_isodata · threshold_kittler · threshold_kapur
*Provenance: seggraph.py — SEGMENTATION 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.