flow op• Data kinds: flow_dense → rgbimage
• Call: import fullseye as fs; fs.ledger.flow_to_rgbimage(flow, index=None, scale=None) (to call the implementation directly, import reprconv; reprconv.flow_to_rgbimage(flow, index=None, scale=None); from the registry, opsreprconv.get("flow_to_rgbimage"))
One slice of a dense scene flow → an rgbimage with hue = direction and value = speed.
Applies the standard visualisation of optical flow (colour wheel) to a z slice of a 3-D flow:
hue = atan2(dy, dx) (in degrees, 0-360), value = |(dy, dx)| / scale, saturation 1. dz is discarded -- this makes explicit that the figure shows only the in-plane components (mixing the discarded component into the colour would leave nobody able to say "what quantity the visible colour is").
One-way. Always burn the colour-wheel legend into the figure together with it (a flow figure that does not state what the colours mean is merely pretty and cannot be read).
Args:
flow: (3, D, H, W).
index: z slice to extract (default = centre).
scale: in-plane speed that corresponds to brightness 1.0 (default = maximum of that slice.
If 0, an all-black image is returned).
Returns:
(H, W, 3) float64, range [0, 1].
Raises:
ValueError: not a dense flow / index out of range / scale <= 0.
• 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.
• representation_conversion — py -3.11 examples/representation_conversion.py
rgbimage as input)—
flow)flow_magnitude · flow_speed · flow_apply
*Provenance: reprconv.py — REPRCONV 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.