Matlab code for rotation invariant radon transform.

I am having two different images of same person and I want to do identification. I found the projection matrix for two images and calculated the correlation coefficient between them. I am getting negative result for this. My system says that these are different persons. What is missing here? I have attached two images of same person. Second image is rotated and I think that is why I am not getting desired results. So, how to use rotation invariant RT?

if true
  % code
% Radon Transform for feature extraction

    theta = 0:179;
    [R,xp] = radon(ex,theta);
    figure, imagesc(theta, xp, R); colormap(hot);              %scale data and display as image
    xlabel('\theta (degrees)'); ylabel('X\prime');
    title('R_{\theta} (X\prime)');
    colorbar                                                   %display color scale
    title('Radon Transform');
%feature extraction
    load('features.mat');
    res=[];
 for i=1:1:62;
    x=z(:,:,i);
    y=corr2(x,R);
    m=min(min(y));
    res=[res m];
 end
  end