region op• Data kinds: region → region
• Call: fullseye.apply(img, "r2_sort_region", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: sort_region (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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ r2_sort_region: 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):
▸ r2_sort_region: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ r2_sort_region: other inputs (docs site)
Keep the k-th largest connected component; k = round(a*(n-1)).
> The detailed description below is the original text — the summary and the headings are translated.
前景マスク(`> 0.5)を scipy.ndimage.label`(既定の 4 連結)で連結成分に
分け、面積(画素数)の降順に並べて `k 番目の成分だけを残す。k` は
`round(a*(n-1)) を [0, n-1] に clip した整数で、a=0` で最大成分、
`a=1 で最小成分、a=0.5 でおおよそ中央の順位の成分。n` は成分数。
`b` は未使用。
返り値は入力と同形の float64 0/1 マスク。成分が無ければ全零。同面積の成分が
複数あるときの順位は保証されない(`numpy.argsort` の順序に依存)。成分数
`n が変わると同じ a` でも選ばれる順位が変わる(相対指定)ので、
「最大成分」を確実に取りたいだけなら `a=0 か select_largest` を使う。
斜め接続だけでつながった画素は別成分として数えられる(4 連結)。前段に
`opening_circle` でくびれを切っておくと成分単位の選択が安定する。
Border handling: treat everything outside the image as background (0) (measured; tools/impl2/border_probe.py).
• 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 r2_sort_region 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_region — py -3.11 examples/gallery2d_region.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.