tb_spad_deadtime_correct — 2D typed op

Data kinds: countscounts

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

Usage

Recover the true photon rate from a dead-time-distorted measured rate.

The exact inverse of the non-paralysable law of

:func:spad_deadtime_apply::

n = m / (1 - m*tau)

A round trip `apply -> correct` is exact to machine precision (measured max

elementwise relative error 6.0e-16 over 2000 rates spanning 1e3 to 5e7 Hz at

`tau = 50 ns`, where the measured rate reaches 71.4% of the 20 MHz

saturation rate).

There is deliberately no paralysable inverse. `m = n*exp(-n*tau)` is not

injective — every measured rate below the maximum `1/(e*tau)` corresponds to

*two* true rates, one below and one above `1/tau` — so returning one of them

would be a fabrication dressed as a correction. Resolve the branch with an

independent measurement (e.g. an attenuator step) and invert it yourself.

*measured_hz* is a 1-D array of measured rates in counts per second;

*dead_time_ns* the dead time in nanoseconds (default 50, the same

placeholder :func:spad_deadtime_apply uses — replace it with the

datasheet value). Returns the corrected true rates as a float64 1-D array.

Raises `ValueError`: negative, non-finite or non-1-D *measured_hz*, a

non-positive *dead_time_ns*, and — instead of returning `inf` or a negative

rate — any measured rate at or above the saturation rate `1/tau`, which no

non-paralysable detector can ever produce.

Typed bridge of the photon op `spad_deadtime_correct into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. a drives dead_time_ns (default 50); b` is 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 counts as input)

identity · tb_spad_deadtime_apply · tb_tcspc_coates_correct · tb_tcspc_irf_convolve · tb_tcspc_background_subtract · tb_dtof_depth · tb_countrate_to_counts · tb_counts_to_countrate

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.