hx_smallest_circle_xld — 2D `halcon_ext` op

• Data kinds: contour → feature

• Call: fullseye.apply(img, "hx_smallest_circle_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_circle_xld (the HALCON reference is a useful guide to its meaning and parameters)

hx_smallest_circle_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_circle_xld: stages (docs site)

Usage

The radius of the minimum enclosing circle of all contour points (approximated with the centroid as centre), as a normalised feature.

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

contour dict の全 contour の点をまとめ、点の平均(重心)を中心として最も遠い点までの距離 `r` を求め、

`r / max(H, W) を np.float64` で返す。真の最小包含円(中心も最適化)ではなく「重心を中心とする包含円」の

近似で、半径は真値以上になる。

• `a, b` は未使用。

• 点が 1 つも無ければ 0.0(有効な値 0 と区別できない)。

複数 contour があっても 1 つの円で包む(contour ごとではない)。正規化は画像の長辺なので、同じ形でも画像サイズが

変わると値が変わる。円らしさを測りたいなら `hx_fit_circle_contour(残差)や circularity_xld`。

region 版の厳密解は `r2_smallest_circle`。

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_circle_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_circle_xld — 2D halcon_ext op