How to convert camera uri to blob object in Phonegap?

In my application, camera image save and retrieve from SQLite. I have camera uri from phonegap api but i want to convert camera uri to blob object and base64 string. I found some of the solution from online but i can't solve my problem. This is convert Base 64 to Blob object. I already tried that link. I can't convert to blob object.



using phonegap-1.4.1.js

Index.js

function onPhotoFileSuccess(imageData){
    console.log(JSON.stringify(imageData));

    var smallImage = document.getElementById('imageview'+imageviewcount);
    smallImage.style.display = 'block';
    smallImage.src = imageData;

    // "imageData" parameter is image uri
    // I don't know how to convert image uri to blob object

    // save to SQLite
    var db = window.sqlitePlugin.openDatabase(Mydb , ver, "", size);        

    db.transaction(function(tx) {tx.executeSql("Insert Into "+ DOPhotoTable +"( RefTranNo,Photo) values(?,?);",["007", blobobject]);});
}

function takeCameraImage(){
    navigator.camera.getPicture(onPhotoFileSuccess, onFail, {  quality: 30, destinationType: Camera.DestinationType.FILE_URI });
}

In onPhotoFileSucces function, i want to convert image uri to blob object.