Comparing 2 frames from video

I want to compare first video frames from original video and edited video, when i'm comparing r and r2 it always show error :

Error in psnr (line 3)

original_img=double(original_img);

Output argument "MSE" (and maybe others) not assigned during call to "psnr".

Error in videoStego (line 186)

[P,MSE]=psnr(r,r2);

But if i'm comparing other variables like r and b2, g and r2, etc it just run smoothly. Here is my code:

ori = VideoReader('Ori.avi');
frame = read(ori,1);
img=frame(:,:,:,1);

r=img(:,:,1);
g=img(:,:,2);
b=img(:,:,3);
    
edited = VideoReader('Edited.avi');
frame2 = read(v,1);
img2=frame2(:,:,:,1);

r2=img2(:,:,1);
g2=img2(:,:,2);
b2=img2(:,:,3);

[P,MSE]=psnr(r,r2);

And here is the psnr code:

function [P,MSE]=psnr(original_img,stego_img)

original_img=double(original_img);
stego_img=double(stego_img);
if (original_img==stego_img)
    PSNR=100;
else
    m = size(original_img,1);  
    n = size(stego_img,2); 
    d = 0 ;  
   for i = 1:m-1 
     for j = 1:n-1  
        d = d + (original_img(i,j) - stego_img(i,j)).^2 ;  
     end  
   end
    MSE=d/(m*n);
    MAX = max( abs(original_img(:)) );
    
    PSNR= 10*log10(MAX^2/MSE);
end
P=PSNR;

Answer 1

[Stephan]

Try:

function [P,MSE]=Untitled(original_img,stego_img)

original_img=double(original_img);
stego_img=double(stego_img);
if (original_img==stego_img)
    PSNR=100;
    MSE=0; % Added this line
else
    m = size(original_img,1);  
    n = size(stego_img,2); 
    d = 0 ;  
   for i = 1:m-1 
     for j = 1:n-1  
        d = d + (original_img(i,j) - stego_img(i,j)).^2 ;  
     end  
   end
    MSE=d/(m*n);
    MAX = max( abs(original_img(:)) );
    
    PSNR= 10*log10(MAX^2/MSE);
end
P=PSNR;
end

[ArianaLaverly]

omg yes i forgot to add that, thank you so much sir!