    explicit CImg(const char *const filename):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(filename);
    }
    explicit CImg(const char *const filename):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(filename);
    }