image registration/find scale factor and recover it

Hi I'm using the code here http://www.mathworks.com/matlabcentral/fileexchange/19731-fourier-mellin-image-registration/content/Register.m

I want to find the "scale factor" of the second image that has been translated,rotated,and scaled then recover the scale, can any one help me?!

[Tao Feng]

Try adding the code: Scale=10^(THETA_X/(size(THETA_PHASE,1)/2));