region op• Data kinds: region → region
• Call: fullseye.apply(img, "boundary", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: boundary (the HALCON reference is a useful guide to its meaning and parameters)
*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):
▸ boundary: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ boundary: other inputs (docs site)
Extracts the outer boundary line (a 1-pixel-wide ring just inside the contour) by subtracting a 1-pixel-eroded version of the region from itself. Converts a filled region into a contour line. Equivalent to HALCON's `boundary` (Reduce a region to its boundary.).
> The detailed description below is the original text — the summary and the headings are translated.
`a, b` は未使用。
穴のある領域: 外周だけでなく穴の輪郭も返る（「領域 − 収縮版」は定義上、外側からも穴の側からも 1 画素を残す。実測で確認）。
画像の縁: 領域が画像の端に接する場合、縁の側も境界に含まれる(外側を背景とみなして収縮するため)。全面が領域の入力では、出力は画像の外周 1 画素の枠になる(8x8 で 28 画素。実測)。
• gallery2d_region family guide
• 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.
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 boundary 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_region — py -3.11 examples/gallery2d_region.py
• voxel_labels_color — py -3.11 examples/voxel_labels_color.py
region as input)identity · reg_erode · reg_dilate · reg_open · reg_close · fill_holes · select_largest · remove_small
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).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.