texture op• Data kinds: image → image
• Call: fullseye.apply(img, "local_std", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*
*The output is shown in a viridis-like pseudo-colour (dark purple = low, yellow = high) so that a field of quantities — distance, phase, orientation, depth — can be read.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ local_std: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ local_std: knob b sweep (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ local_std: other inputs (docs site)
*The 4th column is a colour (H,W,3) input. This op handles colour without crossing channels (it does not convolve the colour channel as a third spatial axis).*
> This operator's description has not been translated yet. The original text follows as it is.
局所窓内の標準偏差を入力と同じ単位で返す(正規化しない)。HALCON の `deviation_image`（Calculate the standard deviation of gray values within rectangular windows.）に相当。
`a が窓の**幅**を、b が窓の**高さ**をそれぞれ 3,5,7,9（_k）に振る —— HALCON の deviation_image(image, width, height)` と同じく矩形窓を取れる。
**`std_filter との違いはここだけで、そこが肝心**: std_filter は出力をその画像の最大値で正規化するので、**画像をまたいで値を比較できない**(弱いテクスチャしか無い画像では雑音が 1.0 まで持ち上がる)。この op は割らないので、**別の画像・別の時刻の値とそのまま比べられる**。HALCON の deviation_image も正規化しないので、意味としてはこちらが忠実。平滑化フィルタの sigma_image` とは別物(あちらは σ を使って平滑化する)。
推定量と誤差(閉形式): 窓の画素数を `n = 幅 x 高さ として、平均を引いた分散を n/(n-1) で不偏化し、さらに sigma の残る偏りを c4(n) ≈ 1 - 1/(4n) で抜く。したがって推定はほぼ無偏(実測: 真値の 99.8〜100.1%)。**1 画素あたりの相対標準誤差は 1/sqrt(2(n-1))`** —— 3x3 窓で約 25%、9x9 窓で約 7.9%(実測が理論と一致)。粗さや雑音量を数字で言うときは、この幅を併記すること。
入力が `[0,1] なら出力は 0 以上 0.55` 以下(最大は窓の半分が 0・半分が 1 のとき)。
• gallery2d_texture_freq 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.
local_std 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_texture_freq — py -3.11 examples/gallery2d_texture_freq.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
texture)std_filter · local_bimodality · scale_select_std · bootstrap_std_error · structure_tensor_orientation · structure_tensor_coherence · gabor · sk_frangi
*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.