convert op• Data kinds: qimage → rgbimage
• Call: import quatimage; quatimage.quaternion_to_rgb(qimage, allow_scalar: 'bool' = False) -> 'np.ndarray' (or opsquat.get("quaternion_to_rgb"))
Vector part of a quaternion image, as linear RGB. → (H, W, 3).
The inverse of :func:rgb_to_quaternion — and, by default, a *checked*
inverse. A quaternion image that picked up a scalar component somewhere (a
Hamilton product with a non-pure quaternion, a monogenic signal handed here
by mistake) is refused rather than silently truncated, because dropping
the `w` component is exactly the kind of loss that produces a plausible
picture from the wrong data. Pass `allow_scalar=True` to opt in to the
truncation when it is what you meant.
The tolerance is relative to the field's own peak modulus
(:data:_MONOGENIC_K_TOL, 1e-9): a quaternion image that really is pure
carries `|w|` at the 1e-17 level after a round trip through two FFTs, and
anything with a meaningful scalar part is many orders above that. Nothing
real lives in between.
Raises `ValueError: *qimage* is not a finite (H, W, 4)` array; or
it has a non-negligible scalar part and `allow_scalar` is False.
• quaternion_monogenic 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.
• quaternion_monogenic — py -3.11 examples/quaternion_monogenic.py
rgbimage as input)convert)*Provenance: quatimage.py — QUAT 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.