typed op• Data kinds: video → video
• Call: fullseye.apply(img, "tb_exponential_background", 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_exponential_background: 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_exponential_background: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ tb_exponential_background: other inputs (docs site)
Motion (GIF: frames / views / slices in turn. The still figure is the complete one; the GIF is supplementary):
Recursive background `bg ← (1−α)·bg + α·frame per frame → (T, H, W) (video`).
> The detailed description below is the original text — the summary and the headings are translated.
最初のフレームで `bg を初期化し、以後 bg += α (frame - bg)` を画素ごとに
繰り返す指数移動平均。状態は背景 1 枚だけ(窓を持たない)。フレーム `t` の
出力はその時点の `bg の写しで、t = 0` は入力の先頭フレームそのもの。
• `video: (T, H, W)` 配列か 2-D フレームの list。整数 dtype は最大値で
`[0, 1] に正規化、float は [0, 1] にクリップ。NaN/Inf は ValueError`。
• `alpha: [0, 1]。時定数はおよそ 1/α` フレーム(0.05 → 約 20 枚)。
0 なら背景は先頭フレームのまま固定、1 なら常に現在のフレーム。
**物体が止まると `1/α` 枚ほどで背景に吸収される**(選択的更新は無い)。
• 返り値: `(T, H, W) float64、[0, 1]`。
• 失敗: `ValueError(形・dtype・alpha` の範囲)。
前景マスクまで欲しいなら同じモデルの `exponential_foreground`。画素ごとの
雑音に閾値を合わせたいなら `running_gaussian_background`。
2-D 進化レジストリへ橋渡しした videostream の op `exponential_background。実装は同じで、呼び出し規約だけ op(v, a, b) に合わせてある。a が alpha(既定 0.05)を振る。b` は未使用。
• 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_video 0.50 0.50 tb_exponential_background 0.50 0.50
▸ Load this pipeline · Load & run
The examples below call the underlying ledger op exponential_background. 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).
• video_streaming — py -3.11 examples/video_streaming.py
video as input)identity · tb_temporal_bandpass · tb_temporal_band_power · tb_temporal_median_window · tb_moving_average_window · tb_background_subtraction_window · tb_frame_difference_causal · tb_exponential_foreground
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.