hx_estimate_sl_al_lr — 2D `halcon_ext` op

• Data kinds: image → feature

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

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

hx_estimate_sl_al_lr: input → output

*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*

*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

Usage

Lee-Rosenfeld: estimate the light source's slant (zenith angle, 0 = head-on to pi/2 = grazing). Normalised to [0,1].

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

画像の平均輝度 `<I> を反射率 1 の Lambertian 面の関係 <I> = albedo * cos(slant)` に当てはめ、

`slant = arccos(<I>) を pi/2 で割った np.float64`(0〜1)で返す。0 が正面光(平均 1.0)、1 が真横

(平均 0)。

• `a, b` は未使用。

• 平均は [0,1] に clip してから `arccos` に渡すので範囲外にはならない。

実質「平均輝度が低いほど slant が大きい」という 1 対 1 の写像で、反射率は 1 と仮定している(暗い素材も

斜光と区別できない)。勾配で補正する版は `hx_estimate_sl_al_zc、反射率の代理値は hx_estimate_al_am`。

`hx_shade_height_field の仰角 b` と組み合わせて陰影を再現する際の目安に使う。

Detailed usage guide

• gallery2d_halcon_ext family guide

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.

Try it in Studio

The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.

hx_estimate_sl_al_lr 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py

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

identity · feature_to_img

Same category (`halcon_ext`)

hx_gen_circle · hx_gen_ellipse · hx_gen_rectangle2 · hx_gen_checker_region · hx_gen_grid_region · hx_gabor · hx_fit_surface1 · hx_fit_surface2

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

hx_estimate_sl_al_lr — 2D halcon_ext op