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)
*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).*
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.
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.
fft_image_inv 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 · 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.