PASCAL - Pattern Analysis, Statistical Modelling and Computational Learning

On Sparsity and Overcompleteness in Image Models
Pietro Berkes, Richard Turner and Maneesh Sahani
Advances in Neural Information Processing Systems Volume 21, 2007.


Computational models of visual cortex, and in particular those based on sparse coding, have enjoyed much recent attention. Despite this currency, the question of how sparse or how over-complete a sparse representation should be, has gone without principled answer. Here, we use Bayesian model-selection methods to address these questions for a sparse-coding model based on a Student-t prior. Having validated our methods on toy data, we find that natural images are indeed best modelled by extremely sparse distributions; although for the Student-t prior, the associated optimal basis size is only modestly over-complete.

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EPrint Type:Article
Project Keyword:Project Keyword UNSPECIFIED
Subjects:Machine Vision
ID Code:3789
Deposited By:Richard Turner
Deposited On:25 February 2008