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])

tb_zero_crossing_rate: input → output

*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*

*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

Stages (the ops that come before → this op, left to right):

▸ tb_zero_crossing_rate: stages (docs site)

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.

Try it in Studio

The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.

img_to_signal 0.50 0.50
tb_zero_crossing_rate 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• (none yet)

Ops the type connects to (they accept `feature` as input)

identity · feature_to_img

Same category (`typed`)

tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal · tb_voxel_grid_downsample

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

tb_zero_crossing_rate — 2D typed op