lamina op• Data kinds: matrix → matrix
• Call: import fullseye as fs; fs.ledger.fly_lamina_filter(movie, dt_s, tau_adapt_s=0.2, tau_lp_s=0.02, mode='divisive', floor=0.001) (to call the implementation directly, import flyvision; flyvision.fly_lamina_filter(movie, dt_s, tau_adapt_s=0.2, tau_lp_s=0.02, mode='divisive', floor=0.001); from the registry, opsflyvision.get("fly_lamina_filter"))
Photoreceptor adaptation + the lamina's band-pass: intensities in, contrast out.
The first thing the optic lobe does to a picture is throw away its brightness. A photoreceptor adapts to the running mean light level and the large monopolar cells (L1/L2) report the *deviation* from it, so the same scene at dawn and at noon arrives at the motion detectors as the same signal. Two closed-form stages, in that order:
1. adaptation — a first-order low-pass of time constant *tau_adapt_s* per ommatidium is the adaptation state a(t). mode="divisive" returns the Weber contrast (x - a)/(a + eps) (eps = floor * mean(x), so it scales with the picture and a dark ommatidium cannot divide by zero); mode="subtractive" returns x - a, which is the same high-pass without the gain control.
2. membrane — a first-order low-pass of time constant *tau_lp_s*, the cell's own bandwidth.
movie: (T, n) intensities, rows = time. mode="divisive" refuses a negative entry (a negative light level is not a measurement) and an all-zero movie (its contrast is 0/0, which would be fabricated rather than measured).
dt_s: sample interval, seconds. tau_adapt_s / tau_lp_s: the two time constants, seconds. floor: the divisive guard, relative to the mean intensity.
Returns (T, n) float64 contrast.
Ground truth, both exact rather than approximate:
• Weber invariance. In "divisive" mode, scaling the whole movie by any positive constant returns *the same array* — both a and eps scale with it. That is the point of the stage and the tests pin it to machine precision.
• The transfer is the product of the two first-order filters. With A = 1 - exp(-dt/tau_adapt) and B = 1 - exp(-dt/tau_lp), the steady-state gain at angular frequency w is |1 - H_A(w)| * |H_B(w)| where H(w) = C/(1 - (1-C) exp(-i w dt)) — a band-pass that blocks DC exactly and is measured at four frequencies in the tests.
Raises ValueError: a non-2-D / too-short / non-finite *movie*, a movie
over MAX_MOVIE_ELEMENTS, a non-positive *dt_s* / *tau_adapt_s* / *tau_lp_s*, a non-positive *floor*, an unknown *mode*, and (divisive only) a negative or all-zero movie.
• 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 canonical algorithm (author, year) and its uses are named in the family usage guide above.
• poc_fly_optomotor_steering — py -3.11 examples/poc_fly_optomotor_steering.py
matrix as input)fly_onoff_split · fly_t4t5_field · fly_flow_from_directions · fly_egomotion_from_flow · fly_hs_readout
lamina)*Provenance: flyvision.py — FLYVISION 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.