Convert base64 to Blob

I'm developing android app with AngularJs & ngCordova,
and in my case, I just can choose to get image file from it's URI.

We don't have "[Select file...]" button to click to set our file directly into $scope object.
For example:

$scope.insertFile = function (file) {

    $scope.fileObject = file;

};

I then use Cordova's plugin, $cordovaFile - readAsDataURL, to get the base64 formatted file.
It's so I can upload my picture through $http and data parameter in form of FormData().

Simply convert into Blob as below does not work:

$cordovaFile.readAsDataURL(file.directory, file.name).then(function(response) {
 // take jpeg image as example
 var imageFile = new Blob(response, {type: 'image/jpeg'}); 
 formData.append('photo', imageFile, file.name);
};

It (the conversion) breaks my image file, because `new Blob()` doesn't automatically encode base64.

I have been struggling to get a non-broken image uploaded for some time until I found a solution that solved my problem below.

Solution
I found a useful HTML5 Filesystem API library code has method that helps correctly converting base64 into Blob.

With this I corrected my code into:

$cordovaFile.readAsDataURL(file.directory, file.name).then(function(response) {
 // take jpeg image as example
 var imageFile = dataURLToBlob(response);
 formData.append('photo', imageFile, file.name);
};

It does convert my image file correctly, and my app is no longer uploading broken image again.

Reference:
http://stackoverflow.com/questions/12168909/blob-from-dataurl