refocus op• Data kinds: lightfield → image2d
• Call: import fullseye as fs; fs.ledger.lf_synthetic_aperture(lf, slope=0.0, mask=None, *, reduce='mean', interp='linear', edge='nearest') (to call the implementation directly, import lightfield; lightfield.lf_synthetic_aperture(lf, slope=0.0, mask=None, *, reduce='mean', interp='linear', edge='nearest'); from the registry, opslightfield.get("lf_synthetic_aperture"))
Refocus through a shaped aperture — and, with reduce="median", through occluders.
Same shift-and-add geometry as lf_refocus, with two additions:
• *mask* — a (V, U) weight array from lf_aperture_mask (or your own). A small mask is a stopped-down aperture: less defocus blur, less light. None weights every view equally.
• *reduce* — how the aligned views are combined. mean is the classical (and linear) synthetic aperture. median is the interesting one: when a foreground occluder covers a *minority* of the views at a pixel, the median rejects it and the background behind it is reconstructed — looking through a fence, or through a rack of parts. max / min are the order-statistic extremes, useful for specular / shadow work. median, max and min use the mask only to *select* views (weight > 0), because an order statistic has no meaningful weighting; that is stated here rather than silently ignoring the weights.
The see-through result is not a metaphor. When fewer than half the views are blocked at a hidden pixel, more than half of them carry the identical background sample and the median is that sample exactly. Measured 2026-09-01 on a 9x9x64x64 field with an occluder covering 25% of the centre view at slope 3.0 (blocking at most 46% of the views at any hidden pixel):
RMS against the true, hidden background was 0.0 for median and 0.159 for mean, with the centre view itself at 0.280. Push the coverage to 35% (up to 60% of views blocked) and the guarantee is gone — the median lands at 0.133, worse than nothing.
Returns a (H, W) 2-D image.
Raises ValueError: *lf* not a valid light field, a *mask* whose shape is not (V, U) or which is non-finite / negative / selects no view, a non-finite or over-large *slope*, unknown *reduce* / *interp* / *edge*.
• lightfield_depth family guide
• 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.
• lightfield_depth — py -3.11 examples/lightfield_depth.py
• poc_compound_eye — py -3.11 examples/poc_compound_eye.py
image2d as input)lf_from_mla · lf_disparity_to_depth · lf_all_in_focus
refocus)lf_refocus · lf_focal_stack · lf_aperture_mask
*Provenance: lightfield.py — LIGHTFIELD 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.