typed op• Data kinds: signal → feature
• Call: fullseye.apply(img, "tb_equivalent_level", 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_equivalent_level: 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_equivalent_level: stages (docs site)
The energy-equivalent level of a record, in dB relative to ref.
L_eq = 10 log10(mean(x_w**2) / ref**2) where x_w is the signal after the chosen weighting. Returns a plain float.
The reference is yours to supply. The default ref=1.0 means dB relative to one unit of the signal's own units; it is not dB SPL, because this library never sees your calibration. Pass ref=20e-6 for pascals.
Measured: a 1 kHz sine of amplitude 1.0 at 16 kHz over exactly 1000 periods gives L_eq = -3.010300 dB with Z weighting, against the closed form 10*log10(1/2) = -3.010300 (difference 2.2e-15 dB), and the same value under A weighting (difference 8.9e-16 dB), because A is 0 dB at 1 kHz. Doubling the amplitude adds 6.020600 dB. Silence returns -200.0.
Silence returns floor_db (default -200) rather than -inf; an -inf in a list of levels destroys every average taken over it afterwards.
A weighted level is only as good as the weighting, and the weighting has a leakage limit this operator inherits in full. A pure tone that is not a whole number of periods in the record comes back too loud — measured +7.7986 dB at 31.5 Hz (a nominal one-third-octave centre) over 0.5 s at 48 kHz, and up to +17.2116 dB at 20.5 Hz — with no exception, no NaN and no warning. weighting="Z" is exempt (it does no filtering) and "C" is nearly so (+0.0493 dB on the same tone); it is "A", whose curve spans about 40 dB across the audio band, that is exposed.
window="hann" is the opt-in remedy: the record is multiplied by a Hann window and the mean square divided by the window's own mean square, which suppresses the leakage almost entirely — the 31.5 Hz error goes from +7.7986 to +0.0534 dB and the 20.5 Hz error from +17.2116 to +0.1841 — while costing about 0.15 dB on records that were exact before. It is not the default, and must not be used when a transient's level is the point: a window makes the answer depend on *where in the record the sound happened*. Measured on a 50 ms burst inside a 0.5 s record (Z weighting, so only the window acts; unwindowed all three are -13.0103 dB as they must be): at the start -36.0587, at the centre -8.8218, at the end -36.0587 — a 27 dB spread produced by nothing but position. Use "hann" for a stationary tonal record, which is exactly the case the leakage ruins, and "none" (the default, an honest energy average) for everything else. The full measurement is in apply_weighting.
Raises ValueError: everything _as_signal refuses, an unknown weighting or window, ref <= 0 (a decibel needs a positive reference; a zero reference makes every level +inf and a negative one makes the ratio negative), rate <= 0.
Typed bridge of the acoustics op equivalent_level into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. a drives ref (default 1); 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_signal 0.50 0.50 tb_equivalent_level 0.50 0.50
▸ Load this pipeline · Load & run
The examples below call the underlying ledger op equivalent_level. 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).
• acoustic_condition_monitoring — py -3.11 examples/acoustic_condition_monitoring.py
feature as input)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.