<input name="pic" id="pic" type="file">
<script>
$('#pic').change(function(){
var file = this;createReader(file.files[0], function (w, h) {
alert(w + ' '+ h);
});
})
createReader = function(file, whenReady) {
var reader = new FileReader;
reader.onload = function (evt) {
var image = new Image();
image.onload = function () {
var width = this.width;
var height = this.height;
if (whenReady) whenReady(width, height);
};
image.src = evt.target.result;
};
reader.readAsDataURL(file);
}
</script>