check image size by url code example
Example: how to get img dimensions from remote url js
function getMeta(url, callback) {
var img = new Image();
img.src = url;
img.onload = function() { callback(this.width, this.height); }
}
getMeta(
"http://snook.ca/files/mootools_83_snookca.png",
function(width, height) { alert(width + 'px ' + height + 'px') }
);