dichromatic op• 資料種類:rgbimage × labels → vector
• 呼叫:import specularity; specularity.illuminant_from_dichromatic_planes(image_rgb, labels, min_pixels=16, min_plane_ratio=1e-06, min_intersection_ratio=1e-06)(或 opsspecular.get("illuminant_from_dichromatic_planes"))
由兩種以上材質恢復光源顏色。→ 單位 3 向量。
> 以下的詳細說明為原文 —— 摘要與標題已翻譯。
Lee's construction (1986). Under the dichromatic model every pixel of one
material lies in the plane spanned by that material's body colour and the
illuminant colour, so each material contributes a plane through the origin
of RGB, and all of those planes contain the illuminant direction. Two
materials with different body colours therefore intersect in exactly one
line, and that line is the answer — a null-space computation, closed form.
*labels* is an `(H, W)` integer map naming the material at each pixel;
negative labels are ignored (background). Each material needs *min_pixels*
pixels and genuine highlight variation: a material seen with no specular
reflection at all has colours along a single ray, which defines no plane.
That is measured by the second-to-first singular ratio of its colour matrix
and rejected below *min_plane_ratio* rather than contributing an arbitrary
normal.
The returned direction is unit length with a positive component sum
(illuminant colours are positive; the null space fixes the line, not the
sign). On synthetic data with three known materials it reproduces the true
illuminant with a maximum component error of 4.4e-14 and an angular error
that rounds to 0.0 degrees (measured in `tests/test_specularity.py`).
*min_intersection_ratio* guards the answer itself: if the plane normals are
nearly parallel — two materials whose body colours differ only in
brightness, which is the same material twice — the intersection is
ill-conditioned and the call raises instead of returning a direction picked
by rounding error.
Raises `ValueError`: shape or dtype problems as in
:func:specular_diffuse_split; *labels* is not an `(H, W)` integer map
matching the image; more than :data:MAX_MATERIALS distinct labels; fewer
than two materials survive the *min_pixels* and *min_plane_ratio* tests; the
surviving planes do not intersect in a well-determined line.
• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。
• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。
• 演算法的正典(作者・年份)與用途見上面的族使用指南。
• poc_white_balance — py -3.11 examples/poc_white_balance.py
• specular_photometric — py -3.11 examples/specular_photometric.py
vector 作為輸入)—
dichromatic)specular_diffuse_split · specular_coefficient_map · specular_free_transform
*Provenance: specularity.py — SPECULAR 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.