hx_smallest_rect2_xld — 2D `halcon_ext` op

• Data kinds: contour → feature

• Call: fullseye.apply(img, "hx_smallest_rect2_xld", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

• HALCON equivalent: smallest_rectangle2_xld (the HALCON reference is a useful guide to its meaning and parameters)

hx_smallest_rect2_xld: 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).*

Stages (the ops that come before → this op, left to right):

▸ hx_smallest_rect2_xld: stages (docs site)

Usage

The area ratio of the minimum-area oriented rectangle (rectangle area / image area; a feature).

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

全 contour の点をまとめ、0°〜84° を 6° 刻みで回転させて軸並行外接矩形の面積を計算し、その最小値を画像面積

`H*W で割って 1 で頭打ちした np.float64` で返す。

• `a, b` は未使用。

• 点が 3 個未満なら 0.0。各辺には `1e-9` が足してあり、点が同一直線上でも面積は厳密には 0 でなく極小値。

角度探索が 6° 刻みなので真の最小面積より最大で数 % 大きく出ることがある。全 contour を 1 つの矩形で包むため、

離れた contour が複数あると間の空白も含む。アスペクト比は `hx_fit_rectangle2_contour`、軸並行版は

`hx_smallest_rect1_xld`。

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.

threshold 0.50 0.50
sk_find_contours 0.50 0.50
hx_smallest_rect2_xld 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_smallest_rect2_xld — 2D halcon_ext op