hx_crop_contours — 2D `halcon_ext` op

• Data kinds: contour → contour

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

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

hx_crop_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.*

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

▸ hx_crop_contours: knob a sweep (docs site)

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

▸ hx_crop_contours: knob b sweep (docs site)

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

▸ hx_crop_contours: stages (docs site)

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

▸ hx_crop_contours: other inputs (docs site)

Usage

Crop contours to the central a×b fraction rectangle (keeping only the points inside).

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

各 contour の点のうち、画像中心 `(H/2, W/2) からの距離が行方向 hh 以内かつ列方向 ww` 以内のものだけを

残し、1 点も残らない contour は捨てて返す。

• `a → 残す高さの半分 hh = (0.3 + 0.6*a) * H/2`(全体の 30%〜90%)。

• `b → 残す幅の半分 ww = (0.3 + 0.6*b) * W/2`(全体の 30%〜90%)。a=b=1 でも周辺 5% は落ちる。

点を間引くだけで分割しないので、矩形の外を回って戻る contour は残った点どうしがつながる(ジャンプ)。

矩形外を完全に無視したい場合は後段で `hx_split_contours。余白を画像端から指定する版は hx_clip_contours`、

1 つのノブで正方形窓にする版は `xg_crop_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_crop_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 `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_crop_contours — 2D halcon_ext op