    CImg<T>& operator+=(const char *const expression) {
      return *this+=(+*this)._fill(expression,true,1,0,0,"operator+=",this);
    }
    CImg<T>& operator+=(const char *const expression) {
      return *this+=(+*this)._fill(expression,true,1,0,0,"operator+=",this);
    }