annotate_scale_bar — ANNOTATE paper op

• Data kinds: image2d → image2d

• Call: import fullseye as fs; fs.ledger.annotate_scale_bar(img, units_per_pixel, unit='µm', corner='rb', target_fraction=0.2, margin=14, color='neutral', thickness=5, font_size=13, box_alpha=0.55, text_color=None, scheme='okabe_ito', font_path=None, layout=None) (to call the implementation directly, import annotate; annotate.annotate_scale_bar(img, units_per_pixel, unit='µm', corner='rb', target_fraction=0.2, margin=14, color='neutral', thickness=5, font_size=13, box_alpha=0.55, text_color=None, scheme='okabe_ito', font_path=None, layout=None); from the registry, opsannotate.get("annotate_scale_bar"))

Usage

Returns an image (image2d): a scale bar of a round length placed in a corner (with value and unit).

Whereas scale_bar has the caller decide the length, this one picks the length from the pixel resolution (annotate_scale_bar_layout). In top corners the text goes below the bar, in bottom corners above it.

Raises

ValueError

Same as annotate_scale_bar_layout + the text does not fit in 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)

• paper_figure — py -3.11 examples/paper_figure.py

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

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

Same category (paper)

annotate_leader_layout · annotate_leader · annotate_markers · annotate_legend · annotate_dimension_layout · annotate_dimension · annotate_angle_layout · annotate_angle

*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.