polarization op• データ種: polsweep → image2d
• 呼び出し: import specularity; specularity.polarization_separate(images, angles_deg=(0.0, 45.0, 90.0, 135.0), max_violation_frac=0.0) (または opsspecular.get("polarization_separate"))
偏光板回転を無偏光成分と直線偏光成分の放射輝度に分ける。→ (diffuse, specular)、どちらも (H, W)。
> 以下の詳細説明は原文のままです —— 要約と見出しは訳出済み。
Fitting `I(t) = 0.5 (S0 + S1 cos 2t + S2 sin 2t)` per pixel gives
`I_min and I_max` in closed form, and the classical separation
(Wolff & Boult 1991; Nayar, Fang & Boult 1997) reads
`diffuse = 2 * I_min` (the unpolarised radiance)
`specular = I_max - I_min` (the linearly polarised radiance)
with `diffuse + specular = I_min + I_max` = the total scene radiance, so
nothing is lost or invented. Round-tripping
:func:polarization_render through this operator returns the inputs with a
maximum absolute error of 3.9e-16 for the four angles of a
division-of-focal-plane sensor and 4.4e-16 for a bare three-angle sweep
(measured in `tests/test_specularity.py`).
Read the names as shorthand. What is recovered exactly is the
unpolarised and polarised parts. Calling them diffuse and specular assumes
diffuse reflection is unpolarised and specular reflection is fully linearly
polarised — true near Brewster's angle for a dielectric, **false at normal
incidence**, where the specular reflection is unpolarised and this operator
returns all of it as "diffuse", and unreliable for metals. The polarisation
route is complementary to the colour route
(:func:specular_diffuse_split), not a replacement: it needs no illuminant
colour and works on textured, multi-material surfaces, but it needs a
favourable geometry.
*max_violation_frac* is the fraction of pixels allowed to fit a negative
minimum radiance before the call fails. The default 0 is fail-closed: a
negative fitted minimum means the modulation exceeded the mean, which no
analyser can produce, and it usually means the frames and *angles_deg* are
out of order. Raise it to clamp sensor-noise-level violations to zero as a
deliberate, recorded choice.
Raises `ValueError: *images* is not an (N, H, W)` stack of at
least 3 frames, or exceeds :data:MAX_LIGHTS / :data:MAX_STACK_ELEMENTS;
*angles_deg* does not match the frame count or leaves the fit
rank-deficient (two angles equal modulo 180); more than
*max_violation_frac* of the pixels fit a negative minimum.
• specular_photometric ファミリ ガイド
• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。
• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。
• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。
• specular_photometric — py -3.11 examples/specular_photometric.py
image2d を入力に取れる)polarization)polarization_render · polarization_dolp_map · polarization_stokes
*Provenance: specularity.py — SPECULAR operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.