Question

I have two images which i would like to compare and do different operations depending on what value the specific pixel has. The problem is that is is really slow and i need to speed the operations up alot, what could be done with the code?

currentFrame = rgbimage; %rgbimage is an 800x450x3 matrix

for i = 1:size(currentFrame, 1)

   for j = 1 : size(currentFrame,2) 

       if currentFrame(i,j) > backgroundImage(i,j) %backgroundimage is an equally sized image which i would like to compare with
          backgroundImage(i,j, :) = double(backgroundImage(i,j, :) +1); 

       elseif currentFrame(i,j) < backgroundImage(i,j)
          backgroundImage(i,j, :) = double(backgroundImage(i,j, :) -1);          
       end


   end

end

diff = abs(double(currentFrame) - double(backgroundImage)); %difference between my backgroundimage and my current frame
fusion = zeros(size(currentFrame)); % A fusion image

for i=1:size(backgroundImage,1)
    for j = 1:size(backgroundImage,2)

           if diff(i,j) > 20

            fusion(i,j, :) = double(currentFrame(i,j, :));

           else
             fusion(i,j, :) = 0;  

           end
    end 
end

Thanks for any help!

Answer 1

You don’t need to loop – you can do stuff like:

indexes = currentFrame > backgroundImage;
backgroundImage(indexes) = backgroundImage(indexes) + 1;

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btw. in your code using currentFrame(i,j) > backgroundImage(i,j) you are just comparing the first of the three color dimensions. Is this intended?