xcv2_warp_logpolar — 2D geometry op

• Data kinds: image → image

• Call: fullseye.apply(img, "xcv2_warp_logpolar", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

Usage

Maps the image onto a (radius, angle) plane using the log-polar transform.

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

`cv2.warpPolar の WARP_POLAR_LOG` モードを使う。中心は画像中心、最大

半径は `min(H, W)/2`。出力の行方向が対数半径、列方向が角度に対応する。

`a, b` は未使用。拡大縮小・回転を新しい画像上の平行移動に変換できる

ため、テンプレートマッチングの前処理（Fourier-Mellin 変換の要素技術）として

使われる。HALCON に対応する単一オペレータは無い。

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.