polarization op• Data kinds: polsweep → stokes
• Call: import specularity; specularity.polarization_stokes(images, angles_deg=(0.0, 45.0, 90.0, 135.0), max_violation_frac=0.0) (or opsspecular.get("polarization_stokes"))
The scene-integrated Stokes vector of a polariser sweep. → (4,), ready for :func:optics.stokes_analyze.
Stokes parameters are linear in radiance, so the spatial mean of the frames
has a Stokes vector that is the mean of the per-pixel ones — the vector a
non-imaging polarimeter looking at the whole field would report. Fitting
`I(t) = 0.5 (S0 + S1 cos 2t + S2 sin 2t) gives (S0, S1, S2)` directly.
S3 is always exactly 0, and that is a limitation, not a measurement. A
set of linear analysers cannot see circular polarisation; a quarter-wave
plate is needed. The returned vector is therefore the linear part of the
truth, and :func:optics.stokes_analyze will report `handedness="linear"`
for it no matter what the scene actually did. Returning an invented `S3`
would be worse, and returning a 3-vector would break the Stokes contract the
optics family is built on.
The result satisfies that contract by construction — ``S0 >= sqrt(S1^2 +
S2^2 + S3^2)``, i.e. degree of polarisation at most 1 — because the same
non-negativity check that guards :func:polarization_separate is exactly
the condition for it. That is why `optics.stokes_analyze` accepts the
output without a further test.
Raises `ValueError: as :func:polarization_separate`.
• specular_photometric 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.
• poc_polarization_specular — py -3.11 examples/poc_polarization_specular.py
• specular_photometric — py -3.11 examples/specular_photometric.py
stokes as input)—
polarization)polarization_render · polarization_separate · polarization_dolp_map
*Provenance: specularity.py — SPECULAR 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.