function resizeImage() {
  var myWidth = 0, myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
var imageWidth = document.getElementById('imgDisplay1').width;
var imageHeight = document.getElementById('imgDisplay1').height;
var heightRatio = imageHeight / myHeight;
var widthRatio = imageWidth / (myWidth);

  if (heightRatio < widthRatio) {
document.getElementById('imgDisplay1').style.width = "auto";
document.getElementById('imgDisplay1').style.height = (myHeight) + "px";
} else {
document.getElementById('imgDisplay1').style.width = (myWidth) + "px";
document.getElementById('imgDisplay1').style.height = "auto";
	}
}