lf_refocus — LIGHTFIELD `refocus` op

• Data kinds: lightfield → image2d

• Call: import lightfield; lightfield.lf_refocus(lf, slope=0.0, *, interp='linear', edge='nearest') (or opslightfield.get("lf_refocus"))

Usage

Shift-and-add refocus: the synthetic-aperture image focused at *slope*.

Every view `(v, u) is shifted by (-s*(v - v_c), -s*(u - u_c))` — the

minus undoes the parallax of a point at slope `s` — and the shifted

views are averaged. Points at that slope add coherently and stay sharp;

everything else is smeared by an amount proportional to its slope

difference times the angular baseline. `slope=0` is the plane the array

was already focused on and returns the plain average of the views.

Ground truth it reproduces exactly (pinned in `tests/test_lightfield.py`):

a single-layer field synthesised at slope `s0 and refocused at s0`

with `edge="wrap" and an integer s0` returns the original texture to

5.6e-16; sweeping the slope, the variance of the result peaks at `s0`

(measured exactly on the sweep grid in all 18 texture/slope combinations

listed in the module docstring), and refocusing at `-s0` does *not* —

which is the check that catches a flipped shift sign.

Returns a `(H, W)` 2-D image.

Raises `ValueError`: *lf* not a valid light field, a non-finite or

over-large *slope* (:data:MAX_ABS_SLOPE), unknown *interp* / *edge*.

Detailed usage guide

• lightfield_depth family guide

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)

• lightfield_depth — py -3.11 examples/lightfield_depth.py

• poc_lightfield_depth — py -3.11 examples/poc_lightfield_depth.py

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

lf_from_mla · lf_disparity_to_depth · lf_all_in_focus

Same category (`refocus`)

lf_focal_stack · lf_aperture_mask · lf_synthetic_aperture

*Provenance: lightfield.py — LIGHTFIELD operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

lf_refocus — LIGHTFIELD refocus op