Learning schemes in using PCA neural networks for image restoration purposes

  • Authors:
  • Ion Rosca;Luminita State;Catalina Lucia Cocianu

  • Affiliations:
  • Department of Computer Science, Academy of Economic Studies, Bucharest, Romania;Department of Computer Science, University of Pitesti, Pitesti, Romania;Department of Computer Science, Academy of Economic Studies, Bucharest, Romania

  • Venue:
  • WSEAS Transactions on Information Science and Applications
  • Year:
  • 2008

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Abstract

Image restoration methods are used to improve the appearance of an image by application of a restoration process that uses a mathematical model for image degradation. The restoration can be viewed as a process that attempts to reconstruct or recover an image that has been degraded by using some a priori knowledge about the degradation phenomenon. Principal component analysis allows the identification of a linear transformation such that the axes of the resulted coordinate system correspond to the largest variability of the investigated signal. The advantages of using principal components reside from the fact that bands are uncorrelated and no information contained in one band can be predicted by the knowledge of the other bands, therefore the information contained by each band is maximum for the whole set of bits. The multiresolution support set is a data structure suitable for developing noise removal algorithms. The multiresolution algorithms perform the restoration tasks by combining, at each resolution level, according to a certain rule, the pixels of a binary support image. The multiresolution support can be computed using the statistically significant wavelet coefficients. We investigate the comparative performance of different PCA algorithms derived from Hebbian learning, lateral interaction algorithms and gradient-based learning for digital signal compression and image processing purposes. The final sections of the paper focus on PCA based approaches for image restoration tasks based on the multirezolution support set as well as on PCA based shrinkage technique for noise removal. The proposed algorithms were tested and some of the results are presented and commented in the final part of each section.