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Changelog

Source: NEWS.md

thinr 0.2.0

All four algorithms are now implemented.

New

  • lee — 2-D adaptation of Lee, Kashyap & Chu (1994). Four directional sub-iterations (N / E / S / W boundary) with crossing-number Euler-invariance check and endpoint preservation.
  • k3m — Saeed et al. (2010). Six-phase iterative thinning: phases 1–5 remove border pixels under progressively permissive lookup tables, plus a final phase 0 cleanup sweep with the strictest table. Includes the crossing-number topology guard and endpoint preservation.

Tests

  • Test suite expanded from 17 to 38 assertions. Each of the six core properties (skeleton size, horizontal-line collapse, idempotence, all-background invariance, isolated-pixel preservation, ring-topology preservation) is exercised across all four methods.

Notes

  • The K3M lookup tables (A1 through A5) in src/k3m.cpp are reconstructed from the algorithm’s published description. The algorithm produces topology-preserving, one-pixel-wide skeletons on the test corpus; reviewers familiar with the paper are invited to verify the table contents against the original publication and submit corrections.
  • 3-D support (the original motivation for Lee’s algorithm) is still not implemented; arrays with more than two dimensions are explicitly rejected. The 2-D Lee adaptation is what ships here.

thinr 0.1.0

Initial release.

Algorithms

  • zhang_suen — Zhang & Suen (1984). Full implementation.
  • guo_hall — Guo & Hall (1989). Full implementation.
  • lee — Lee (1994). Stub; planned for v0.2.
  • k3m — Saeed et al. (2010). Stub; planned for v0.2.

API

  • thin(image, method) — main dispatching function.
  • thinImage(x) — drop-in replacement for EBImage::thinImage(). Uses Zhang-Suen.
  • Accepts logical, integer, and numeric input matrices; preserves storage mode in the return.

Known limitations

  • 2-D matrix inputs only; higher-dimensional arrays are not yet supported.
  • Lee and K3M are stubs that error with a clear message. Two algorithms are enough to validate the package API and to provide an immediate drop-in replacement for EBImage::thinImage(); the other two follow in v0.2 once the underlying implementations are written.