cv_nlmeans — 2D smoothing op

Data kinds: imageimage

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

cv_nlmeans: 入力 → 出力

*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).*

Usage

Non-local means denoising (OpenCV implementation, grayscale variant). Applies the same idea as sk_nlm (searching the whole image for similar patches and averaging them) using OpenCV's fast implementation.

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

HALCON に直接対応するものは無い。実装は `cv2.fastNlMeansDenoising(_u8(v), h=3+20*a, templateWindowSize=7, searchWindowSize=21)` を 255 で割ったもの —— a はフィルタ強度 h を 3〜23 に振る(大きいほど強く除去されディテールも失われる)。パッチ/探索窓は既定サイズに固定。b は未使用。

Detailed usage guide

gallery2d_smoothing_rank 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.

Try it in Studio

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.

cv_nlmeans 0.35 0.50

▸ Load this pipeline  ·  Load & run

Runnable examples (verified samples that actually call this op)

gallery2d_smoothing_rankpy -3.11 examples/gallery2d_smoothing_rank.py

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

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

Same category (smoothing)

gaussian · mean_box · bilateral · unsharp · sk_tv · sk_wavelet · sk_rolling_ball · sk_nlm


*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.