tb_zero_crossing_rate — 2D typed op

• Data kinds: signal → feature

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

Usage

Fraction of adjacent samples that change sign — a cheap pitch/noisiness cue.

Exact zeros are neither a crossing nor a sign: a crossing is counted only when

the sign changes between consecutive *non-zero* samples, and the rate divides

by the number of adjacent sample pairs `len(x) - 1. So [1, 0, 1, 0, 1]` is

`0.0 and [1, 0, -1] is 0.5 (before 2026-09-02 diff(sign(x))` counted

every touch of zero as a crossing: `1.0` for both).

Typed bridge of the 1d op `zero_crossing_rate 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 feature as input)

identity

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.