JSP：如何将HTML img标记中的图像作为blob存储到数据库中

I have one web application for capturing image from webcaam using flash player. after capturing image from webcam I am displaying it's preview in HTML img tag and also capturing image url in hidden form fields which I am using to store that image in my database. But my query is how do I store that image from that image tag as blob in my database and most of the solution I reviewed in that I found of storing image in database were uploading image from system and then storing and retrieving it from databse.I have one web application for capturing image