How can I do summation pixel by pixel?

Below is my code

im = imread('test.png');
imshow(im);

[rows columns] = size(im);

numberOfPixels = rows*columns;

r_t = 0;

Red = im(:,:,1);

pixel = 0;

for i=1:rows

      for j=1:columns

          red = impixel(Red,i,j);

          if red == 255

              r_t = r_t + 0;

          else

              r_t = r_t + red;

          end

      end
end

when i type impixel(Red,1,1)

I think the answer should be just 255, but command window display 255 255 255

Answer 1

[Matt J]

 Red=im(:,:,1);
 rt=sum( Red(Red~=255) , 'double')

[test test]

thanks alot, if I want exclude white pixel value of the image, then it should be like

Red=im(:,:,1);
Green=im(:,:,2);
Blue=im(:,:,3)

rt=sum( (Red(Red~=255) && Green(Green~=255) && Blue(Blue~=255)) , 'double')

?

[Matt J]

No, it should be

notwhite = ~( Red==255&Green==255&Blue==255);

rt=sum( Red(notwhite) ,'double') ;

[test test]

this is for the whole image?

[Matt J]

It is the sum of all red channel values in pixels that are not completely white.

[test test]

is it possible i compare the pixel value of R channel, G channel and B channel at the same time and set a condition where R==255 && G==255 && B==255 then only i sum up the pixel value

[Matt J]

That's what we did.

[test test]

thank you very much