The Computer Journal Advance Access originally published online on July 29, 2007
The Computer Journal 2009 52(1):64-79; doi:10.1093/comjnl/bxm055
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Inpainting and Zooming Using Sparse Representations
1 GREYC CNRS UMR 6072, Image Processing Group, ENSICAEN 14050, Caen Cedex, France
2 CEA-Saclay, DAPNIA/SEDI-SAP, Service d'Astrophysique, F-91191 Gif sur Yvette, France
3 Department of Computer Science, Royal Holloway, University of London, Egham TW20 0EX, UK
* Corresponding author: fionn{at}cs.rhul.ac.uk
Received 30 June 2006; revised 15 February 2007
Representing the image to be inpainted in an appropriate sparse representation dictionary, and combining elements from Bayesian statistics and modern harmonic analysis, we introduce an expectation maximization (EM) algorithm for image inpainting and interpolation. From a statistical point of view, the inpainting/interpolation can be viewed as an estimation problem with missing data. Toward this goal, we propose the idea of using the EM mechanism in a Bayesian framework, where a sparsity promoting prior penalty is imposed on the reconstructed coefficients. The EM framework gives a principled way to establish formally the idea that missing samples can be recovered/interpolated based on sparse representations. We first introduce an easy and efficient sparse-representation-based iterative algorithm for image inpainting. Additionally, we derive its theoretical convergence properties. Compared to its competitors, this algorithm allows a high degree of flexibility to recover different structural components in the image (piecewise smooth, curvilinear, texture, etc.). We also suggest some guidelines to automatically tune the regularization parameter.
Key Words: EM algorithm sparse representations inpainting interpolation penalized likelihood