hx_regress_contours — 2D `halcon_ext` op

• Data kinds: contour → feature

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

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

hx_regress_contours: 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_regress_contours: stages (docs site)

Usage

Fit a regression line to each contour and return the mean residual (the deviation from the line; a feature). Small = line-like.

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

点数 3 以上の各 contour について、点の重心を通る全最小二乗直線(座標共分散の最小固有ベクトルを法線とする)を

当て、点から直線までの距離の RMS を求める。全 contour の RMS を平均し `max(H, W)` で割って 1 で頭打ちした

`np.float64` を返す。

• `a, b` は未使用。

• 有効な contour が無ければ 0.0(「完全な直線」と区別できない)。

小さいほど直線的。直線そのものの傾きや位置は返さない(当てはめ結果が要るなら `fit_line_contours`)。

折れ線としての角の数を見たいなら `hx_split_contours` で分割してから線分数を数える。点数 2 以下の contour は

評価から外れる。1 本の contour だけを対象にした同種の指標は `xg_regress_contours`。

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_regress_contours 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_regress_contours — 2D halcon_ext op