leader_line — ANNOTATE pointer op

• Data kinds: image2d × text → image2d

• Call: import fullseye as fs; fs.ledger.leader_line(img, anchor_xy, target_xy, text=None, color='emphasis', width=2, cap='dot', cap_size=4, elbow=True, scheme='okabe_ito', style=None, **text_kw) (to call the implementation directly, import annotate; annotate.leader_line(img, anchor_xy, target_xy, text=None, color='emphasis', width=2, cap='dot', cap_size=4, elbow=True, scheme='okabe_ito', style=None, **text_kw); from the registry, opsannotate.get("leader_line"))

Usage

A leader line — from the note's position (anchor_xy) to its target (target_xy).

With elbow=True it is drawn with 2 segments, horizontal → diagonal (the annotation is less likely to cover the subject). At the end point a cap mark ('dot'/'arrow'/'cross'/'none') is placed. If text is given, a text_box is placed on the anchor_xy side. Additional **text_kw are passed straight to text_box.

Raises

ValueError

unknown cap, non-finite coordinates, line outside the image.

Detailed usage guide

• figure_annotation family guide

Background guides (the physics and conventions behind this op)

• dataset_conventions — Training-dataset conventions — COCO / YOLO / VOC and pitfalls in visual inspection

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)

• annotate_gallery — py -3.11 examples/annotate_gallery.py

• poc_kendama — py -3.11 examples/poc_kendama.py

Ops the type connects to (they accept image2d as input)

text_box · arrow · label_points · crosshair · legend_box · color_bar · scale_bar · axes_frame

Same category (pointer)

arrow · label_points · crosshair

*Provenance: annotate.py — ANNOTATE 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.