halcon_ext op• Data kinds: image → image
• Call: fullseye.apply(img, "hx_gen_bandpass", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: gen_bandpass (the HALCON reference is a useful guide to its meaning and parameters)
*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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ hx_gen_bandpass: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ hx_gen_bandpass: knob b sweep (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ hx_gen_bandpass: 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).*
An ideal band-pass (an annular mask in the frequency domain, inner radius a and bandwidth b).
> The detailed description below is the original text — the summary and the headings are translated.
`hx_gen_lowpass と同じ正規化周波数半径 r(fftshift 済、中心=DC)に対し r_lo <= r <= r_hi` の
円環を 1 とする 0/1 の float 画像(周波数領域マスク)を返す。入力 `v` は形状の取得にのみ使う。
• `a → 内半径 r_lo = 0.05 + 0.4*a`(0.05〜0.45)。
• `b → 帯域幅 r_hi - r_lo = 0.05 + 0.3*b(0.05〜0.35)。外半径は r_lo + 幅` で最大 0.8 だが、半径が
約 0.707 を超える周波数は存在しないので、大きな a, b では円環の外側が画像外に出て実質ハイパスになる。
`hx_gen_bandfilter は「中心半径と半幅」で同じ円環を指定する別パラメータ化。fft_generic` などの中心=DC
スペクトルとの画素積で使う。
Value comparability (measured): the output is normalised by that image's own maximum (the output maximum is always 1.0, and scaling the input leaves the output unchanged). Values therefore cannot be compared across images — a feature of the same strength takes a different value depending on what the strongest feature in that image happens to be, and in an image holding only weak features the noise is lifted to 1.0. To compare across images, rescale by a common reference.
• gallery2d_halcon_ext 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.
hx_gen_bandpass 0.50 0.50
▸ Load this pipeline · Load & run
• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
halcon_ext)hx_gen_circle · hx_gen_ellipse · hx_gen_rectangle2 · hx_gen_checker_region · hx_gen_grid_region · hx_gabor · hx_fit_surface1 · hx_fit_surface2
*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.