halcon_ext op• Data kinds: image → image
• Call: fullseye.apply(img, "hx_gen_derivative_filter", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: gen_derivative_filter (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_derivative_filter: knob a sweep (docs site)
Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):
▸ hx_gen_derivative_filter: knob b sweep (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ hx_gen_derivative_filter: 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).*
A derivative filter in the frequency domain. `a is the order of the derivative, b` its direction.
> The detailed description below is the original text — the summary and the headings are translated.
HALCON の `gen_derivative_filter` は Derivative(x / y / xx / yy / xy)と
次数を取るが、ここは長らく `|f|` を正規化して返すだけで、**入力の中身も
つまみも一切見ていなかった** —— 2026-09-02 実測で、同じ形なら
`a/b` を変えても、別の絵を渡しても、返りがバイト一致だった
(兄弟の `hx_gen_lowpass / hx_gen_highpass / hx_gen_bandfilter` は
つまみで変わるので、この 1 件だけ浮いていた)。
• `a : 階数 1〜2(|f| か |f|^2`)。2 階はラプラシアンに対応する。
• `b : 向き。0 で x 方向 |f_x|、1 で y 方向 |f_y|、間は等方 |f|`
へ滑らかに混ぜる(0.5 でちょうど等方)。
返りは周波数領域のフィルタそのもの(HALCON の gen_* と同じ約束)なので、
入力は形を決めるためだけに使う。ただし形だけでなくつまみでちゃんと変わる
ようになったので、進化が階数と向きを選べる。
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_derivative_filter 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.