MATLAB: How to write matlab code for moments

feature extractionmomants

i have this code for calculating moments function [M]= moments(I) [r c]=size(I); m=zeros(r,c); % geometric moments for i=0:1 for j=0:1 for x=1:r for y=1:c m(i+1,j+1)=m(i+1,j+1)+(x^i*y^j*I(x,y)); end end end end
xb=m(2,1)/m(1,1); yb=m(1,2)/m(1,1);
% central moments u=[ 0 0 0 0;0 0 0 0;0 0 0 0;0 0 0 0]; for i=0:3 for j=0:3 for x=1:r for y=1:c u(i+1,j+1)=u(i+1,j+1)+(x-xb)^i*(y-yb)^j*I(x,y); end end end end
% scale invariant moments n=[ 0 0 0 0;0 0 0 0;0 0 0 0;0 0 0 0]; for i=0:3 for j=0:3 n(i+1,j+1)=u(i+1,j+1)/(u(1,1)^(1+(i+j)/2)); end end
%rotation invariant moments I_1= n(3,1)+ n(1,3); I_2=(n(3,1)- n(1,3) )^2+ (2*n(2,2))^2; I_3=(n(4,1)-3*n(2,3))^2+ (3*n(3,2)-n(1,4))^2; I_4=(n(4,1)+n(2,3))^2+ (n(3,2)+n(1,4))^2; I_5=(n(4,1)-3*n(2,3))*(n(4,1)+n(2,3))*((n(4,1)+n(2,3))^2-3*(n(3,2)+n(1,4))^2)+(3*n(3,2)-n(1,4))*(n(3,2)+n(1,4))*(3*(n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2); I_6=(n(3,1)-n(1,3))*((n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2)+ 4*n(2,2)*(n(4,1)+n(2,3))*(n(3,2)+n(1,4)); I_7=(3*n(3,2)-n(1,4))*(n(4,1)+n(2,3))*((n(4,1)+n(2,3))^2- 3*(n(3,2)+n(1,4))^2 )- (n(1,4)-3*n(2,3))*(n(3,2)+n(1,4))*(3*(n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2);
M= [I_1 I_2 I_3 I_4 I_5 I_6 I_7];
but it gives same values for all images is this correct way to calculate moments?

Best Answer

You may need to convert your input image to double. In uint8 numbers greater than 255 became 255.
function [M]= moments(I)
I=double(I);
[r c]=size(I); 
m=zeros(r,c); 
% geometric moments 
for i=0:1 
    for j=0:1 
        for x=1:r 
            for y=1:c 
                m(i+1,j+1)=m(i+1,j+1)+(x^i*y^j*I(x,y)); 
            end
        end
    end
end
xb=m(2,1)/m(1,1); 
yb=m(1,2)/m(1,1);
% central moments 
u=[ 0 0 0 0;0 0 0 0;0 0 0 0;0 0 0 0]; 
for i=0:3 
    for j=0:3 
        for x=1:r 
            for y=1:c 
                u(i+1,j+1)=u(i+1,j+1)+(x-xb)^i*(y-yb)^j*I(x,y); 
            end
        end
    end
end
% scale invariant moments 
n=[ 0 0 0 0;0 0 0 0;0 0 0 0;0 0 0 0]; 
for i=0:3 
    for j=0:3 
        n(i+1,j+1)=u(i+1,j+1)/(u(1,1)^(1+(i+j)/2)); 
    end
end
%rotation invariant moments 
I_1= n(3,1)+ n(1,3); 
I_2=(n(3,1)- n(1,3) )^2+ (2*n(2,2))^2; 
I_3=(n(4,1)-3*n(2,3))^2+ (3*n(3,2)-n(1,4))^2; 
I_4=(n(4,1)+n(2,3))^2+ (n(3,2)+n(1,4))^2; 
I_5=(n(4,1)-3*n(2,3))*(n(4,1)+n(2,3))*((n(4,1)+n(2,3))^2-3*(n(3,2)+n(1,4))^2)...
    +(3*n(3,2)-n(1,4))*(n(3,2)+n(1,4))*(3*(n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2); 
I_6=(n(3,1)-n(1,3))*((n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2)+ 4*n(2,2)*(n(4,1)...
    +n(2,3))*(n(3,2)+n(1,4)); 
I_7=(3*n(3,2)-n(1,4))*(n(4,1)+n(2,3))*((n(4,1)+n(2,3))^2- 3*(n(3,2)+n(1,4))^2 )...
    - (n(1,4)-3*n(2,3))*(n(3,2)+n(1,4))*(3*(n(4,1)+n(2,3))^2-(n(3,2)+n(1,4))^2);
M= [I_1 I_2 I_3 I_4 I_5 I_6 I_7];
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