Hi, new to this forum and quite the novice at MatLab. Anyway, I am trying to analyze the RGB of images. I made some quick code to look at three squares of one image, taking the sum of each RGB. However, the matrix results are always 255. i read that in MatLab i don't have to declare variable types, but something isn't right; the numbers should be much larger. Here's the code:

clear
t='c:\users\my.self\desktop\test\IMG_0001.jpg';
h=[700, 1020, 1450];
v=1700;
rcol=0;
gcol=0;
bcol=0;
mag=zeros(3);
q=imread(t);
for i=1:3
    ybeg=h(i);
    for x=v:v+50
        for y=ybeg:ybeg+50
            rcol=q(x,y,1);
            gcol=q(x,y,2);
            bcol=q(x,y,3);
            mag(i)=mag(i)+rcol+gcol+bcol;
        end
    end
end

So looking at 50x50 grids. Any ideas? Thanks.