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Visual input for pen-based computers


Munich, Mario Enrique (2000) Visual input for pen-based computers. Dissertation (Ph.D.), California Institute of Technology.


The development of computer technology has had a parallel evolution of the interface between humans and machines, giving rise to interface systems inspired by human communication. Vision has been demonstrated to be the sense of choice for face recognition, gesture recognition, lip reading, etc. This thesis presents the design and implementation of a camera-based, human-computer interface for acquisition of handwriting. The camera focuses on the sheet of paper and images the hand writing; computer analysis of the resulting sequence of images enables the trajectory of the pen to be tracked and the times when the pen is in contact with the paper to be detected. The recovered trajectory is shown to have sufficient spatio-temporal resolution and accuracy to enable handwritten character recognition.

Signatures can be acquired with the camera-based interface with enough resolution to perform verification. This thesis describes the performance of a visual-acquisition signature verification system, emphasizing the importance of the parameterization of the signature to achieving good classification results. The generalization error of the verification algorithm is estimated using a technique that overcomes the small number of example signatures and forgeries provided by the subjects.

The problem of establishing correspondence and measuring the similarity of a pair of planar curves, in our case a pair of signatures, arises in many application in computer vision and pattern recognition. This thesis presents a new method for comparing planar curves and for performing matching at sub-sampling resolution. The analysis of the algorithm as well as its structural properties are described. The performance of the new technique is evaluated for the problem of signature verification and compared to the performance of the well-known Dynamic Programming Matching algorithm.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Electrical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Perona, Pietro
Thesis Committee:
  • Perona, Pietro (chair)
  • Psaltis, Demetri
  • Arvo, James R.
  • Burl, Michael C.
  • Abu-Mostafa, Yaser S.
Defense Date:21 January 2000
Author Email:mariomu (AT)
Record Number:CaltechETD:etd-03152006-094551
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:962
Deposited By: Imported from ETD-db
Deposited On:15 Mar 2006
Last Modified:26 Dec 2012 02:34

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