hx_radial_distort_contour — 2D `halcon_ext` op

• Data kinds: contour → contour

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

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

hx_radial_distort_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_radial_distort_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_radial_distort_contour: stages (docs site)

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

▸ hx_radial_distort_contour: other inputs (docs site)

Usage

Apply radial distortion r' = r(1 + k r^2) to a contour (k from (a−0.5): barrel or pincushion).

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

各 contour の点を画像中心 `(H/2, W/2) からの相対座標 d にし、正規化半径 r = |d| / (max(H, W)/2)` に

対して `d' = d * (1 + k*r^2)` と伸縮させた contour を返す(放射歪みモデルの 1 次項)。

• `a → 歪み係数 k = (a - 0.5) * 1.5(-0.75〜+0.75)。k < 0 で点が中心に寄る(樽型)、k > 0` で

外へ広がる(糸巻き型)、a=0.5 で無変化。

• `b` は未使用。

半径は画像長辺の半分で正規化しているので、画像の隅で `r が 1 前後になり、k = ±0.75` なら隅の点は

1.75 倍/0.25 倍まで動く。逆変換は無い(`k` の符号を反転しても厳密には戻らない)。レンズ歪みの影響を contour

計測(`hx_fit_circle_contour` 等)で試す、あるいは合成的にデータを増やす用途。

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_radial_distort_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_radial_distort_contour — 2D halcon_ext op