cv_dist — 2D `region` op

• Data kinds: region → image

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

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

cv_dist: 入力 → 出力

*The figure is the real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*

Usage

Distance transform (OpenCV implementation, L2/Euclidean approximation). For each pixel in the foreground region, computes the distance to the nearest background pixel and returns it as an image - used as preprocessing for extracting a region's "thickness" or its centerline.

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

HALCON の distance_transform(Compute the distance transformation of a region.)に相当。実装は `cv2.distanceTransform(_u8(binm(v)), DIST_L2, maskSize=3)` を正規化したもの(cv2 は float32 で返すが、契約に合わせて float64 化 —— 2026-09-03 実測でベンチマーク済み)。maskSize=3 は 3x3 近傍での近似計算(厳密なユークリッド距離ではなく高速近似)。a, b は未使用。

Detailed usage guide

• gallery2d_region 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
cv_dist 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_region — py -3.11 examples/gallery2d_region.py

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

identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter

Same category (`region`)

reg_erode · reg_dilate · reg_open · reg_close · fill_holes · select_largest · remove_small · invert_region

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

cv_dist — 2D region op