checking image size before upload

Question

I noticed when uploading a profile pic to Twitter that its size is checked before upload. Can anyone point me to a solution like this?

Thanks

Answer 1

This works perfectly for me

var _URL = window.URL || window.webkitURL;

$("#file").change(function(e) {
var file, img;


if ((file = this.files[0])) {
    img = new Image();
    img.onload = function() {
        if((this.width < 800)||(this.height < 400)){
            alert('Image too small. Images must be bigger than 800 x 400');
            $('#file').val('');
        }

    };
    img.onerror = function() {
        alert( "not a valid file: " + file.type);
    };
    img.src = _URL.createObjectURL(file);

}

});

Kudos to the original creator: http://jsfiddle.net/4N6D9/1/

I modified this to specify the min width and height of an upload.