extract op• Data kinds: labels2d → mask
• Call: import fullseye as fs; fs.ledger.blob_region(labels: 'Any', index: 'int') -> 'np.ndarray' (to call the implementation directly, import blob2d; blob2d.blob_region(labels: 'Any', index: 'int') -> 'np.ndarray'; from the registry, opsblob.get("blob_region"))
Extracts 1 object as a binary region (bool). index is 1-based.
A selection op that just returns labels == index. The numbers are the consecutive 1..n that blob_label assigned, and 0 is the background.
• labels: 2-D integer label image (output of blob_label / blob_select / blob_split). bool masks are rejected (to prevent the accident of "measuring several objects as 1", it prompts you to apply blob_label first). float is also rejected (it cannot decide which object 0.999 is). Negative numbers raise ValueError.
• index: an int with 1 <= index <= labels.max(). 0 (background) or out of range raises ValueError. Same numbering as the label column of blob_features and the result of blob_select_largest (renumbered from 1).
• Returns: bool of shape (H, W). It is never empty (the number always exists -- however, a home-made label image with gaps that was not renumbered by blob_select can return all False).
The extracted region can be passed directly to blob_distance (distance transform), the blob_overlay overlay, or the contour drawing of annotate_outline.
• 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_gear_tooth_metrology — py -3.11 examples/poc_gear_tooth_metrology.py
• poc_particle_sizing — py -3.11 examples/poc_particle_sizing.py
mask as input)extract)blob_boundaries · blob_overlay
*Provenance: blob2d.py — BLOB 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.