frequency op• Data kinds: image → image
• Call: fullseye.apply(img, "sk_butterworth", 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 real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*
Butterworth filter (frequency domain). Applies an FFT to the image and acts as a high-pass filter that passes only components above a specified cutoff frequency (called with the default `high_pass=True`). Emphasizes high-frequency components of contours and texture.
> 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(空欄)。実装は `filters.butterworth(v, cutoff_frequency_ratio=0.05+0.3*a) を [0,1]` に clip しただけ —— a はカットオフ比を 0.05〜0.35 に振る(小さいほど低周波まで削られ、応答が強く/広く出る)。b は未使用。ハイパスなので低コントラストな平坦領域は 0 付近に落ち、直流成分(平均輝度)の情報は失われる。
• 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.
sk_butterworth 0.40 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
frequency)lowpass · highpass · fft_image · power_real · power_byte · phase_rad · highpass_image · bandpass_image
*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.