gaussian_transport_map — COLORTRANSPORT matching op

• Data kinds: points × points → matrix

• Call: import fullseye as fs; fs.ledger.gaussian_transport_map(src_samples, ref_samples) (to call the implementation directly, import colortransport; colortransport.gaussian_transport_map(src_samples, ref_samples); from the registry, opscolortransport.get("gaussian_transport_map"))

• Return value through the ledger: fullseye.ledger.gaussian_transport_map(...) returns only the declared out type matrix (the underlying function also returns auxiliary values). When you need what was dropped, use fullseye.ledger.gaussian_transport_map.raw(...) or call colortransport.gaussian_transport_map directly.

Usage

The Monge map (A, b) when two point sets are taken to be normal distributions.

x -> A (x - m1) + m2, where A is S1^-1/2 (S1^1/2 S2 S1^1/2)^1/2 S1^-1/2 (the closed form of the Bures geometry). Because it transports the covariance as a whole, the correlation between channels is preserved.

When degenerate (one of the covariances is singular) the inverse square root cannot be formed -- fudging it with a pseudo-inverse would give a map that "pretends to have transported although it has not", so ValueError.

Background guides (the physics and conventions behind this op)

• colorimetry — Colorimetry and spectra — colour is fixed only by spectrum × illuminant × observer

References (sample data, literature)

• 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.

Runnable examples (verified samples that actually call this op)

• color_transport — py -3.11 examples/color_transport.py

Ops the type connects to (they accept matrix as input)

sinkhorn · sinkhorn_distance · sinkhorn_divergence · transport_cost

Same category (matching)

histogram_match · color_transfer


*Provenance: colortransport.py — COLORTRANSPORT 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.