band_snr — MOTIONMAG temporal op

• Datenarten: video → table

• Aufruf: import fullseye as fs; fs.ledger.band_snr(video, f_lo, f_hi, fps) -> 'dict' (die Implementierung direkt: import motionmag; motionmag.band_snr(video, f_lo, f_hi, fps) -> 'dict'; aus dem Register: opsmotionmag.get("band_snr"))

Verwendung

Misst, was das Zeitband eines Clips enthält und was es kostet -> dict.

> Die ausführliche Beschreibung unten ist der Originaltext — Zusammenfassung und Überschriften sind übersetzt.

Every quantity is a measured mean-square power obtained from the per-pixel temporal DFT (Parseval-normalised so that the bins of one pixel sum to that pixel's mean square), averaged over pixels:

• static_power — the DC bin. The scene that is simply *there*.

• band_power — the bins inside [f_lo, f_hi]. Coherent motion plus whatever noise happens to fall in the band.

• out_of_band_power / out_of_band_bins — everything else except DC. With broadband sensor noise this is the noise floor, and noise_power_per_bin is its per-bin density.

• noise_in_band = noise_power_per_bin * band_bins — how much of band_power is expected to be noise.

• motion_power = max(band_power - noise_in_band, 0) and motion_snr_db = 10*log10(motion_power / noise_in_band).

• image_snr_db = 10*log10(static_power / (band_power + out_of_band_power)) — the static scene against everything that flickers.

The two SNRs answer different questions and magnification moves only one of them. Scaling the in-band phase by alpha scales the in-band motion *and* the in-band noise by the same factor, so the true motion SNR cannot

improve: magnification never makes a measurement more certain than the recording was. What does change is image_snr_db, because the temporal fluctuation of the output frames grows like alpha^2 while the static scene does not.

A caveat that matters when this is run on an already-magnified clip. motion_snr_db here divides the in-band signal by a noise floor estimated from the *out-of-band* bins, and magnification does not touch those. Applied to a magnified video it therefore credits alpha^2 more in-band power against an unchanged noise estimate and reports an improvement that did not occur — measured, +6.86 dB at alpha = 2 on a clip whose true motion SNR cannot have moved. motion_magnify knows the gain and returns the corrected figure as motion_snr_out_db; use that one, not result["snr_out"]["motion_snr_db"].

snr_clamped is True when a reported dB hit the [-100, +100] window (a noiseless synthetic has zero out-of-band power, which is a division by zero rather than an infinite SNR).

Ausführlicher Anwendungsleitfaden

• Leitfaden zur Familie motion_magnification

Referenzen (Beispieldaten, Literatur)

• Katalog der Beispieldaten (Download-URLs / Lizenzen) — 2-D nutzt skimage.data (BSD/Public Domain) plus synthetische Bilder, 3-D nennt Download-URLs echter Datenquellen (Stanford, PDS, …).

• Herkunft und Literatur der Operatoren — die Quellen der Forschung/Verfahren, auf denen diese Operatorfamilie beruht.

• Der kanonische Algorithmus (Autor, Jahr) und seine Anwendungen stehen im Familienleitfaden oben.

Ausführbare Beispiele (verifizierte Samples, die diesen Operator wirklich aufrufen)

• motion_magnification — py -3.11 examples/motion_magnification.py

• poc_motion_magnification — py -3.11 examples/poc_motion_magnification.py

Typkompatible Folge-Operatoren (nehmen table als Eingabe)

complex_steerable_reconstruct

Gleiche Kategorie (temporal)

temporal_bandpass · temporal_band_power


*Provenance: motionmag.py — MOTIONMAG Operator-Registry. Diese Notiz wird von tools/opdocs.py md erzeugt (nicht von Hand bearbeiten).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.