fly_lamina_filter — FLYVISION `lamina` op

• 資料種類:matrix → matrix

• 呼叫: 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)(要直接呼叫實作,import flyvision; flyvision.fly_lamina_filter(movie, dt_s, tau_adapt_s=0.2, tau_lp_s=0.02, mode='divisive', floor=0.001);從台帳取用則 opsflyvision.get("fly_lamina_filter"))

用法

> 該運算子的說明尚無譯文,以下照原文給出。

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 :data: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.

詳細使用指南

• fly_vision 族使用指南

參考(範例資料・文獻)

• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。

• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。

• 演算法的正典(作者・年份)與用途見上面的族使用指南。

可執行的範例(實際呼叫該運算子並已驗證的樣例)

• poc_fly_optomotor_steering — py -3.11 examples/poc_fly_optomotor_steering.py

型別可銜接的下一個運算子(可接受 `matrix` 作為輸入)

fly_onoff_split · fly_t4t5_field · fly_flow_from_directions · fly_egomotion_from_flow · fly_hs_readout

同類別(`lamina`)

fly_onoff_split

*Provenance: flyvision.py — FLYVISION 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*

fly_lamina_filter — FLYVISION lamina op

用法