polarization op• Data kinds: polsweep → image2d
• Call: import specularity; specularity.polarization_dolp_map(images, angles_deg=(0.0, 45.0, 90.0, 135.0), max_violation_frac=0.0) (or opsspecular.get("polarization_dolp_map"))
Degree of linear polarisation, per pixel. → (H, W) in [0, 1].
`sqrt(S1^2 + S2^2) / S0`, from the same sinusoid fit as
:func:polarization_separate. It answers the question that decides whether
a polariser is worth mounting at all: 1 means the light at that pixel is
fully linearly polarised and a crossed analyser extinguishes it completely,
0 means the polariser will only cost you a stop of exposure.
Being a ratio, it is invariant to exposure: scaling every frame by 1e-4,
1e4 or 1e8 moves it by at most 3.9e-16 (measured), which is what makes it
comparable across a production line where the lamps age. Not *bit*-
identical — the least-squares fit rounds differently at a different scale —
and the difference between "invariant" and "bit-identical" is the kind of
claim this library measures rather than asserts.
Pixels with zero total radiance have no degree of polarisation (every ratio
would be 0/0) and are returned as 0.0 rather than as NaN; that is a
convention, and it is stated here because a NaN spreading into a
thresholding routine is exactly the silent failure this library refuses.
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.
• specular_photometric — py -3.11 examples/specular_photometric.py
image2d as input)polarization)polarization_render · polarization_separate · polarization_stokes
*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.