typed op• Datenarten: qimage → qimage
• Aufruf: fullseye.apply(img, "tb_iqft2", a=0.5, b=0.5) (das 2-D-Modell ist ein Bild plus zwei skalare Regler a,b∈[0,1])
Inverse Quaternionen-Fourier-Transformation eines zentrierten Spektrums. → (H, W, 4).
> Die ausführliche Beschreibung unten ist der Originaltext — Zusammenfassung und Überschriften sind übersetzt.
The exact inverse of :func:qft2 for the same side and the same mu:
measured round-trip error `2.22e-15` for both sides on a standard-normal
`(32, 32, 4) field. The kernel is exp(+mu * 2*pi*(...))` applied on the
side named, and the `1/(H*W)` normalisation is carried here, as in
`numpy.fft.ifft2`.
Using the wrong side does not raise. `iqft2(qft2(q, "left"), "right")`
returns a finite, plausible quaternion image that is simply not `q`:
measured `max|err| = 1.113` on a random colour image whose own range is
`0.9994 (another seed: 1.063 against 1.0), and — the dangerous case — only 0.054` against a range of
`1.076` on a grey-axis-dominated one, which is small enough to survive a
look at the picture. The `side` argument is required at both ends for
exactly this reason, and the two calls must agree: nothing in the data
records which transform produced it, so nothing downstream can catch the
mismatch for you.
Raises `ValueError: *spectrum* is not a valid (H, W, 4)` field;
*side* is not `'left' / 'right'`; *mu* is not a finite non-zero
3-vector.
Typed bridge of the quat op `iqft2 into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. This op has no tunable parameter; a and b` are unused.
• Katalog der Beispieldaten (Download-URLs / Lizenzen) — 2-D nutzt skimage.data (BSD/Public Domain) plus synthetische Bilder, 3-D nennt Download-URLs echter Datenquellen (Stanford, PDS, …).
• Herkunft und Literatur der Operatoren — die Quellen der Forschung/Verfahren, auf denen diese Operatorfamilie beruht.
• (noch keine)
qimage als Eingabe)identity · tb_quaternion_to_rgb · tb_quat_norm · tb_quat_conjugate_image · tb_quat_normalize_image · tb_monogenic_amplitude · tb_monogenic_phase · tb_monogenic_orientation
typed)tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_angle_3points · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal
*Provenance: ops.py — 2D Operator-Registry. Diese Notiz wird von tools/opdocs.py md erzeugt (nicht von Hand bearbeiten).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.