Emean=findEnergy(x)

function Emean=findEnergy(x)
% FINDENERGY creates an gradient img from a given RGB or grayscale image.
% The vertical and horizontal gradients are found using a Sobel operator
% and the gradient magnitude is found for each channel and averaged if RGB
% image is input.
%
% Author: Danny Luong
%         http://danluong.com
%
% Last updated: 12/20/07

[rows cols dim]=size(x);

%sobel operator used to calculate gradient image
Grd=[ -1 -2 -1;
       0  0  0;
       1  2  1];

% Grd1=[ 0 -1 0; -1 4 -1 ; 0 -1 0];

Emean=zeros(rows,cols);
for i=1:dim
    Eh(:,:,i)=conv2(x(:,:,i),Grd,'same');
    Ev(:,:,i)=conv2(x(:,:,i),Grd.','same');
    E(:,:,i)=abs(Eh(:,:,i))+abs(Ev(:,:,i));

%     E(:,:,i)=conv2(X(:,:,i),Grd1,'same');
end
Emean=1/dim*sum(E,3);   %finds average gradient image if RGB image