The Symmetric Logarithmic Image Processing Model Laurent Navarro ∗ , Guang Deng † and Guy Courbebaisse ‡ * Ecole Nationale Supérieure des Mines, CSI-EMSE, CNRS UMR 5307, LGF, F-42023, Saint-Etienne, France. Email: navarro@emse.fr. † Corresponding author. Department of Electronic Engineering, La Trobe University Victoria 3083, Australia. Phone: +61 3 9479 2036. Fax: +61 3 9471 0524, Email: d.deng@latrobe.edu.au. ‡ CREATIS, CNRS UMR 5220, Inserm U 1044, UCB Lyon 1, INSA Lyon, University of Lyon, 7 Av. J. Capelle, 69621 Villeurbanne, France. Email: guy.courbebaisse@insa-lyon.fr. Abstract In this paper, a new extension of logarithmic image processing (LIP) model, called Symmetric Logarithmic Image Processing (SLIP), is proposed. Inspired by the previously developed symmetric models, the SLIP model defines a vector space on a symmetric bounded set. The development is aimed at (1) maintaining the physical interpretation of the LIP model and (2) solving the potential out-of-range problem which the LIP model has. The SLIP model is also able to deal with transmitted and reflected light images. The advantage of the SLIP is demonstrated through an image enhancement application using the generalized unsharp masking algorithm. Keywords: Logarithmic image processing model, generalized linear system, unsharp masking. Preprint submitted to Digital Signal Processing July 15, 2013