function new_mask = rtsCropMask(mask, max_pixels)

%convert to logical
%mask = mask > 0;

if nnz(mask) < max_pixels
    new_mask = mask;
else
    j = 0;
    for i = 1:length(mask(:))
        if mask(i) > 0
            j = j + 1;
            if j == max_pixels
                last_pixel = i;
            end
        end
    end
    new_mask = zeros(size(mask, 1), size(mask, 2));
    new_mask(1:last_pixel) = mask(1:last_pixel);
end