挺简单的

var img_url = $input_verifycode.next('img').attr('src');
var r = new XMLHttpRequest();
r.open("GET", img_url);
r.responseType = "blob";
r.onload = function(e){
	var data = new FormData();
	data.append('image_data', this.response);
	$.ajax({
		url: 'http://localhost:8088/upload.php',
		data: data,
		cache: false,
		contentType: false,
		processData: false,
		type: 'POST',
		success: function(data){
		//alert('上传成功');
		}
	});
};
r.send();