phase_rad — 2D `frequency` op

• Data kinds: image → image

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

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

Usage

The FFT phase `angle(F) linearly mapped from radians to [0,1] (0 = -pi, 1 = +pi). Visualizes the phase information lost by the power spectrum (which carries most of the spatial positional information of the structure). Corresponds to HALCON's phase_rad` (Return the phase of a complex image in radians).

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

`a, b` は未使用。位相はノイズにきわめて敏感で、平坦な領域ではほぼ

無意味な値になる点に注意。

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)

• acoustic_condition_monitoring — py -3.11 examples/acoustic_condition_monitoring.py

• 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_real · power_byte · 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).*

phase_rad — 2D frequency op