tb_monogenic_phase — 2D typed op

Data kinds: qimageimage

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

*No figure: this op takes qimage as input. A Studio program starting from an image cannot reach that type — see the runnable examples below for how it is used.*

Usage

Local phase `atan2(|R|, f)` of a monogenic signal. → (H, W).

In `[0, pi]` — the monogenic phase is measured against the *magnitude* of

the Riesz vector, whose sign is carried by the orientation instead, so the

range is a half turn rather than a full one. That is the standard

convention (Felsberg & Sommer) and it is stated here because a caller

arriving from `complexops.cx_phase (whose raw range is (-pi, pi]`) will

otherwise assume a full turn and see a "wrapped" map that is not wrapped.

`display=True maps [0, pi] to [0, 1]` for viewing; the default is

`False — the **opposite** of cx_phase`'s default, deliberately,

because the consumers of this quantity in this module are numerical, and a

display scaling that arrives silently in a measurement is a factor of `pi`

that nothing announces.

Phase is the quantity a translation shifts linearly, which is why the whole

motion half of this module reads it. For an edge, phase 0 means the peak of

a bright line, `pi/2 a step edge and pi` the peak of a dark line — the

local *structure type*, independent of contrast.

Raises `ValueError`: the input is not a valid quaternion field, or its

`k` component is non-zero; *display* is not a bool.

Typed bridge of the quat op `monogenic_phase 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.

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.

Runnable examples (verified samples that actually call this op)

• (none yet)

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

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

Same category (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. 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.