power_real — 2D frequency op

• Data kinds: image → image

• Call: fullseye.apply(img, "power_real", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

• HALCON equivalent: power_real (the HALCON reference is a useful guide to its meaning and parameters)

Usage

An image obtained by normalizing the absolute value of the real part of the FFT, `|Re(F)| (unlike the logarithmic power spectrum of fft_image, this looks only at the real part without taking a logarithm). An approximation corresponding to HALCON's power_real` (Return the power spectrum of a complex image) -- HALCON's original definition is the power |F|^2, but here the absolute value of the real part is used as a substitute.

> The detailed description below is the original text — the summary and the headings are translated.

`a, b` は未使用。

Detailed usage guide

• gallery2d_texture_freq family guide

References (sample data, literature)

• 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.

Runnable examples (verified samples that actually call this op)

• gallery2d_texture_freq — py -3.11 examples/gallery2d_texture_freq.py

Ops the type connects to (they accept image as input)

identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter

Same category (frequency)

lowpass · highpass · sk_butterworth · fft_image · 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.