Scale Image based on proportions change of the parent http://www.ajaxblender.com/howto-resize-image-proportionally-using-javascript.html
scaleSize: function(maxW, maxH, currW, currH){
var ratio = currH / currW;
if(currW >= maxW && ratio <= 1){
currW = maxW;
currH = currW * ratio;
} else if(currH >= maxH){
currH = maxH;
currW = currH / ratio;
} else {
if( currW > currH ){
currW = maxW;
currH = maxW * ratio;
}else{
currH = maxH;
currW = maxH / ratio;
}
}
return [ Math.round(currW), Math.round(currH) ];
}