How to solve this error (index must be a positive integer or logical)?

function s = subim(f, m, n, rx, cy)
%SUBIM Extracts a subimage, s, from a given image, f.
%The subimage is of size m-by-n, and the coordinates of its top, left corner are (rx, cy).

s = zeros(m, n);
rowhigh = rx + m - 1;
colhigh = cy + n - 1;
xcount = 0;
for r = rx:rowhigh
    xcount = xcount + 1;
    ycount = 0;
    for c = cy:colhigh
        ycount = ycount + 1;
        s(xcount, ycount) = f(r, c);
    end
end

I am try to run the code, but this got error. Attempted to access f(0,0); index must be a positive integer or logical.

f = imread('13100.jpg');
[m,n]=size(f);
s = zeros(m, n);
rx = 0;
cy = 0;
s = zeros(m, n); 
rowhigh = rx + m - 1; 
colhigh = cy + n - 1; 
xcount = 0;  
for r = rx:rowhigh 
    xcount = xcount + 1;
    ycount = 0; 
    for c = cy:colhigh 
        ycount = ycount + 1;
        s(xcount, ycount) = f(r, c); 
    end
end

%

[Stephen23]

@Mei Synn Tan: rather than doing this in a loop you should use indexing with vectors. Also note that images are often 3D, which your code does not take into account.

Answer 1

[KSSV]

This:

rx = 0;
cy = 0;

Should be

rx = 1;
cy = 1;

You are taking indices 0, note that, matlab will not take -ve or zero indices. Indices should be +ve integers.

[Mei Synn Tan]

Many thanks in advance!