region op• Data kinds: region → region
• Call: fullseye.apply(img, "r3_polar_trans_region", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: polar_trans_region (the HALCON reference is a useful guide to its meaning and parameters)

*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).*
Remaps the region to polar coordinates centred on its centroid (equivalent to HALCON `polar_trans_region`).
> The detailed description below is the original text — the summary and the headings are translated.
出力の行が半径軸(0〜`rmax)、列が角度軸(0〜angle_end)にあたる。a(0〜1)は半径方向の広がり(rmax は重心から最遠画素までの距離に 0.25+0.75*a を掛けたもの)、b(0〜1)は角度方向の掃引幅(angle_end = 2*pi*(0.25+0.75*b)`)を振る。最近傍サンプリング。出力の形状は入力と同じ。
• 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 r3_polar_trans_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.