count_contours — 2D `features` op

• Data kinds: contour → feature

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

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

count_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):

▸ count_contours: stages (docs site)

Usage

A feature that returns the number of contours (objects). Equivalent to HALCON's `count_obj` (Number of objects in a tuple.).

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

`a, b` は未使用。輪郭リストの長さをそのまま返すだけ。

• 入力は XLD 輪郭 dict `{"shape": (H, W), "cs": [(N_i, 2), ...]}。数えるのは cs` の要素数で、各輪郭の点数・長さ・閉じているかは見ない(点が 1 つの輪郭も 1 本)。

• 返り値は `np.float64(sort feature`)。0 本なら 0.0。

• 前段の輪郭抽出(`sk_find_contours / edges_sub_pix / hx_gen_contours_skeleton)がどう分割するかで値が決まる —— 同じ形でも 1 画素の切れ目で本数が増える。本数を安定させたいなら select_contours(長さでの選別)や hx_union_adjacent_contours` を間に置く。

• 「物体の数」として使うなら `connection(region の連結成分)+ count_regions` 相当のほうが切れ目に強い。

Detailed usage guide

• gallery2d_features 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
count_contours 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_features — py -3.11 examples/gallery2d_features.py

Ops the type connects to (they accept `feature` as input)

identity · feature_to_img

Same category (`features`)

effective_bit_depth · blob_count · area_frac · total_length · vol_count · sk_euler · sk_entropy_feat · sk_blur_effect

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

count_contours — 2D features op