pairs_to_image2d — REPRCONV pairs op

• Data kinds: pairs → image2d

• Call: import fullseye as fs; fs.ledger.pairs_to_image2d(pairs, shape=(64, 64)) (to call the implementation directly, import reprconv; reprconv.pairs_to_image2d(pairs, shape=(64, 64)); from the registry, opsreprconv.get("pairs_to_image2d"))

Usage

Pairs (N,2) → a scatter-density image (H, W). The third exit from pairs.

Maps column 0 to the row direction and column 1 to the column direction, normalises each by its own min-max and drops them into bins (2-D histogram). It is meant for viewing as a phase plot or correlation plot, and is irreversible (the quantization by the bin width + the normalisation discard the scale of the absolute values). So that the discarded scale can be restored, extent is... not returned -- returning it would make this no longer an image2d. If needed, use x_min etc. of pairs_to_table.

A constant column (min == max) is gathered at position 0.5 (this avoids division by 0, but so that it is not read as "the density is concentrated at the centre", only 1 bin is raised).

Args:

pairs: (N, 2).

shape: (H, W).

Returns:

(H, W) float64, density normalised to a maximum of 1.0.

Raises:

ValueError: bad shape / non-finite / shape exceeds the limit.

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)

• representation_conversion — py -3.11 examples/representation_conversion.py

Ops the type connects to (they accept image2d as input)

keypoints_from_image2d

Same category (pairs)

pairs_to_signal · pairs_to_table


*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.