frequency op• Data kinds: image → image
• Call: fullseye.apply(img, "fft_image_inv", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
• HALCON equivalent: fft_image_inv (the HALCON reference is a useful guide to its meaning and parameters)
Treats the input image directly as an array in the frequency domain, applies an inverse FFT, and maps the real part to [0,1] with `signed01 (0.5 is zero). HALCON's fft_image_inv (Compute the inverse fast Fourier transform of an image.) is originally an operator that reverses the complex spectrum (real/imaginary pair) produced by fft_image, but because this stand-in is constrained by a pipeline contract that only handles a single grayscale image, it is an approximation that inverse-transforms the pixel values as-is, as a complex array with zero imaginary part (note that feeding the output of fft_image` into this does not produce a semantically valid round trip).
> The detailed description below is the original text — the summary and the headings are translated.
`a, b` は未使用。
• 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.
• 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 · sk_butterworth · fft_image · power_real · power_byte · phase_rad · highpass_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.