sigma_image — 2D smoothing op

Data kinds: imageimage

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

HALCON equivalent: sigma_image (the HALCON reference is a useful guide to its meaning and parameters)

sigma_image: 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-linear smoothing via a sigma filter. It averages only the neighboring pixels close to the center pixel value (`|x-mean|<σ) -- near edges, tones from the opposite side are not mixed into the average, so this results in noise removal that preserves edges better than a mean filter. Equivalent to HALCON's sigma_image` (Non-linear smoothing with the sigma filter.).

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

`a が窓の一辺を {3,5,7,9} で振る(内部の平均計算にも使う)。b` が

許容帯域(シグマ、0.05〜0.4)を振る。両方が使われる。近傍がすべて帯域外の

画素は元の値のまま残る。

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.

sigma_image 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.