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Machine Vision and Applications

, Volume 13, Issue 2, pp 80–94 | Cite as

Affine-invariant curve normalization for object shape representation, classification, and retrieval

  • Yannis Avrithis
  • Yiannis Xirouhakis
  • Stefanos Kollias
Original papers

Abstract.

A novel method for two-dimensional curve normalization with respect to affine transformations is presented in this paper, which allows an affine-invariant curve representation to be obtained without any actual loss of information on the original curve. It can be applied as a preprocessing step to any shape representation, classification, recognition, or retrieval technique, since it effectively decouples the problem of affine-invariant description from feature extraction and pattern matching. Curves estimated from object contours are first modeled by cubic B-splines and then normalized in several steps in order to eliminate translation, scaling, skew, starting point, rotation, and reflection transformations, based on a combination of curve features including moments and Fourier descriptors.

Key words: Curve normalization – Affine invariants – Shape analysis – Image and video retrieval 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • Yannis Avrithis
    • 1
  • Yiannis Xirouhakis
    • 1
  • Stefanos Kollias
    • 1
  1. 1.Image, Video and Multimedia Systems Laboratory, Electrical and Computer Engineering Department, National Technical University of Athens, 9, Iroon Polytechniou Str., Zografou 157 73, Athens, Greece; e-mail: {iavr,jxiro}@image.ntua.gr, Tel.: +30-1-7722521, Fax: +30-1-7722492 GR

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