hx_gen_parallel_contour — 2D `halcon_ext` op

• Data kinds: contour → contour

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

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

hx_gen_parallel_contour: 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.*

Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):

▸ hx_gen_parallel_contour: knob a sweep (docs site)

*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_gen_parallel_contour: stages (docs site)

On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):

▸ hx_gen_parallel_contour: other inputs (docs site)

Usage

Generate the parallel (normal-offset) contour of each contour (the signed distance comes from (a−0.5)).

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

各 contour(点数 2 以上)の接線を `np.gradient(c, axis=0)` で求め、それを 90° 回した単位法線

`(-t_col, t_row) / |t| の方向に dist` だけ全点をずらした contour を返す。元の contour は出力に含まれない

(置き換わる)。

• `a → 符号つきオフセット dist = (a - 0.5) * 10`(-5〜+5 画素。a=0.5 で無変化)。

• `b` は未使用。

• 接線長が 1e-9 未満の点(重複点)は法線 0 とし動かさない。点数 1 の contour はそのまま。

法線の向きは contour の進行方向で決まる(左右どちらが正かは点列の向き次第)。曲率半径より大きくずらすと

自己交差する(`hx_test_self_intersect` で検出可能)。輪郭を太らせ/痩せさせた形の比較や、計測線を境界から

一定距離に置くのに使う。

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.

threshold 0.50 0.50
sk_find_contours 0.50 0.50
hx_gen_parallel_contour 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 `contour` as input)

identity · select_contours · smooth_contours · fit_line_contours · contours_to_region · count_contours · total_length · select_contours_xld

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_gen_parallel_contour — 2D halcon_ext op