W2D: 2 dimensional warping for image recognition


W2D is a software package for appearance based image recognition supporting different pixel to pixel deformation models:


W2D was developed in the course of the diploma thesis of Christian Gollan in 2003 (tutor: D. Keysers, supervisor: H. Ney). It has been (and continues to be) extended by Daniel Keysers and Thomas Deselaers with some new deformation models.


W2D is released unter the GNU General Public License Version 2.



You are welcome to use the code under the terms of the licence for research or commercial purposes, however please acknowledge its use with a citation to one of the publications below, e.g. [1] for handwritten characters or general images and [2] for medical images.

The code is in constant development and more features will be added in the future. If you find bugs or have questions please contact one of the authors.


  1. D. Keysers, C. Gollan, and H. Ney. Local Context in Non-linear Deformation Models for Handwritten Character Recognition. In ICPR 2004, International Conference on Pattern Recognition, Cambridge, UK, August 2004.
  2. D. Keysers, C. Gollan, and H. Ney. Classification of Medical Images using Non-linear Distortion Models. In BVM 2004, Bildverarbeitung für die Medizin 2004, Berlin, Germany, pages 366-370, March 2004. (.pdf)
  3. C. Gollan. Non-Linear Deformation Models for Image Object Recognition (in German). Diploma Thesis, Lehrstuhl für Informatik VI, RWTH Aachen University, Aachen, Germany, September 2003. .pdf, .ps, .ps.gz)




left to right: test image, distorted reference image, distortion grid, reference image (produced using the -x -p options to W2D)
Christian Gollan,Thomas Deselaers, Daniel Keysers
Last modified: Tue Jun 1 23:06:28 CEST 2004