Iterative nth power/root image equalization

This is an image equalization code....

This code has been written in Spring 2008 by me, Gholamreza Anbarjafari (Shahab). You can use this code for any research and academic purposes as far as you refer to the following work:
Hasan Demirel and Gholamreza Anbarjafari, "HSI Based Colour Image Equalization using Iterative nth Root and nth Power", 5th International Conference on Electrical and Computer Systems (EECS’08), November 27-28, 2008, Lefke, North Cyprus.
Feel free to contact us for any furthur information:
{hasan.demirel, shahab.jafari}@emu.edu.tr
http://faraday.ee.emu.edu.tr/shahab
http://faraday.ee.emu.edu.tr/hdemirel
(c) Demirel and Anbarjafari -2008

The iterative proposed method for equalization is based on achieving a normalized image with mean of 0.5 in R, G and B channels. A new image X in a colour channel can be obtained by using this equation:
X = X^teta; where teta =ln (0.5)/ln (mean-of-X);
one can easily calculate the PSNR using the calcpsnr commend available in this address: http://www.mathworks.com/matlabcentral/fileexchange/22241