typed op• Data kinds: counts → counts
• 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])
*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.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ tb_spad_deadtime_correct: knob a sweep (docs site)
*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_spad_deadtime_correct: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ tb_spad_deadtime_correct: other inputs (docs site)
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.
• 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 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_counts 0.50 0.50 tb_spad_deadtime_correct 0.50 0.50
▸ Load this pipeline · Load & run
The examples below call the underlying ledger op spad_deadtime_correct. This bridge op is the same implementation adapted to the fn(v, a, b) convention, so the behaviour carries over unchanged (only the call form differs).
• photon_timeresolved — py -3.11 examples/photon_timeresolved.py
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
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).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.