polar_trans_image_ext — 2D geometry op

• Data kinds: image → image

• Call: fullseye.apply(img, "polar_trans_image_ext", 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_image_ext (the HALCON reference is a useful guide to its meaning and parameters)

Usage

Converts the entire image into a polar (radius, angle) representation (`cv2.warpPolar, forward direction, linear interpolation). The center is fixed at the image center, and the maximum radius is min(h,w)/2. a and b are unused (shares the polar branch of _sh_geom with polar_trans_image`).

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

HALCON の `polar_trans_image_ext`（中心・半径範囲・角度範囲などを個別指定できる、環状の一部だけを切り出して極座標変換する拡張版演算）とは異なり、この実装は画像全体を固定パラメータで変換する簡略近似 —— 環状領域や角度範囲の指定はできない。

Detailed usage guide

• gallery2d_geometry 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.

Runnable examples (verified samples that actually call this op)

• gallery2d_geometry — py -3.11 examples/gallery2d_geometry.py

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

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

Same category (geometry)

rotate_img · rescale_img · affine_warp · sk_swirl · mirror_image · transpose_region · rotate_image · zoom_image_factor

*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.