principal_comp — 2D `color` op

• Data kinds: color → color

• Call: fullseye.apply(img, "principal_comp", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

• HALCON equivalent: principal_comp (the HALCON reference is a useful guide to its meaning and parameters)

Usage

Performs principal component analysis (PCA) on 3 channels and reorders the color space in descending order of variance. Corresponds to HALCON's `principal_comp` (computes the principal components of a multichannel image).

> The detailed description below is the original text — the summary and the headings are translated.

画素を (H*W, 3) の行列とみなして平均を引き、共分散行列の固有値分解

（`np.linalg.eigh`）で固有ベクトルを求め、固有値の降順に射影する。

各成分は画像内で min-max により個別に [0,1] へ正規化するため、

出力の明るさは元画像のスケールと無関係になる（正規化後は毎回フルレンジ）。

a, b は未使用。

Detailed usage guide

• gallery2d_color_artistic family guide

Background guides (the physics and conventions behind this op)

• colorimetry — 測色と分光の知識 — 色は「分光 × 光源 × 観測者」でしか決まらない

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)

• gallery2d_color_artistic — py -3.11 examples/gallery2d_color_artistic.py

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

identity · trans_from_rgb · trans_to_rgb · linear_trans_color · rgb1_to_gray · rgb3_to_gray · access_channel · edges_color

Same category (`color`)

cfa_to_rgb · trans_from_rgb · trans_to_rgb · linear_trans_color · rgb1_to_gray · rgb3_to_gray · access_channel

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

principal_comp — 2D color op