ellipse — ANNOTATE shape op

• Data kinds: image2d → image2d

• Call: import fullseye as fs; fs.ledger.ellipse(img, center, radii, angle_deg=0.0, color='neutral', width=2, fill=False, alpha=1.0, scheme='okabe_ito') (to call the implementation directly, import annotate; annotate.ellipse(img, center, radii, angle_deg=0.0, color='neutral', width=2, fill=False, alpha=1.0, scheme='okabe_ito'); from the registry, opsannotate.get("ellipse"))

Usage

An ellipse (rotated by angle_deg, filled with fill=True).

Raises

ValueError

radius not positive, non-finite, alpha outside [0,1].

Drawing: maps each pixel into local coordinates (u, v) rotated by angle_deg and tests with q = (u/ra)^2 + (v/rb)^2. fill=True is q <= 1, fill=False is the band |sqrt(q) - 1| <= max(1, width) / (2 min(ra, rb)) (no anti-aliasing). Because the band width is normalised by the minor axis, on a flat ellipse the line looks thicker towards the ends of the major axis (approximation).

• center: (x, y), x = column, y = row. May be outside the image.

• radii: (ra, rb) [px]. ra along the angle_deg direction, rb perpendicular to it. Both positive.

• angle_deg: rotation angle [degrees]. Clockwise from the x axis (screen coordinates, y pointing down).

• width: line width [px] (when fill=False).

• img / color / alpha / scheme are handled as in rounded_rect (float64 copy, [0, 1], role name or RGB).

• Return value: float64 of the same shape as the input.

ra == rb gives a circle. When overlaying measurement results (row, col, phi, ra, rb of an ellipse fit), translate them into center=(col, row), angle_deg=degrees(phi).

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_dimensional_inspection — py -3.11 examples/poc_dimensional_inspection.py

• poc_driving_crossing — py -3.11 examples/poc_driving_crossing.py

• poc_driving_lateral — py -3.11 examples/poc_driving_lateral.py

• poc_driving_pass — py -3.11 examples/poc_driving_pass.py

• poc_machine_condition_fusion — py -3.11 examples/poc_machine_condition_fusion.py

• poc_peg_insertion_tactile — py -3.11 examples/poc_peg_insertion_tactile.py

• poc_public_camera_heading_real — py -3.11 examples/poc_public_camera_heading_real.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 (shape)

rounded_rect · filled_polygon · arc

*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.