Inside window scroll function multiple if else statement not working

How to add multiple if or else inside window scroll function? You can see the example below.

$(window).scroll(function() {

    var scroll = $(window).scrollTop();

    if (scroll <= 650) {
      $j('.innerimage').attr('src', 'images/side_1.png');
    }

    if (scroll >= 850) {
      $j('.innerimage').attr('src', 'images/side_2.png');
    }
});