How to assign rgb values to multiple row,col of a matrix ?

for i=1:2%max(label(:))
    [rows, cols] = find(label == i);
    image(rows,cols,:) = [0,0,0];
end

but I get the error subscripted assignment dimension mismatch

Answer 1

[Adam]

doc sub2ind

Answer 2

[Guillaume]

If the R, G and B values are identical:

image(sub2ind(size(image), repmat(rows, 1, 3), repmat(cols, 1, 3), repmat([1 2 3], numel(rows), 1)) = 0;

If not,

image(sub2ind(size(image), repmat(rows, 1, 3), repmat(cols, 1, 3), repmat([1 2 3], numel(rows), 1)) = repmat([R G B], numel(rows), 1);

unfortunately, neither is particularly straightforward.