Adaptive Elastic Models for Hand-Printed
  Character Recognition
  Geoffrey Hinton, Christopher Williams 
  and Michael Revow
  Department of Computer Science
  University of Toronto
  Abstract
  Hand-printed digits can be modeled as splines that are governed by
  about 8 control points.  For each known digit, the control points have preferred
  'home' locations, and deformations of the digit are generated by moving the control points
  away from their home locations.  Images of digits can be produced by placing Gaussian
  ink generators uniformly along the spline.  Real images can be recognized by finding
  the digit model most likely to have generated the data.  For each digit model we use
  an elastic matching algorithm to minimize an energy function that includes both the
  deformation energy of the digit model and the log probability that the model would
  generate the inked pixels in the image.  The model with the lowest total energy wins.
    If a uniform noise process is included in the model of image generation, some of
  the inked pixels can be rejected as noise as a digit model is fitting a poorly segmented
  image.  The digit models learn by modifying the home locations of the control points.
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  Advances in Neural Information Processing Systems 4. MIT Press,
  Cambridge MA. 
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