On file reader's call back change corresponding input elements scope's property?

On file reader's call back change corresponding input elements scope's
property?

With reference to question File pick with Angular JS, on file reader's on
load i want to modify a parent scope's property. Consider
$scope.fileLoaded = false; //initially
$scope.file_changed = function(element, $scope) {
$scope.$apply(function(scope) {
var photofile = element.files[0];
var reader = new FileReader();
reader.onload = function(e) {
$scope.fileLoaded = true; // I intend to do!
...
};
reader.readAsDataURL(photofile);
});
});
How do i achieve this for HTML:
<input ng-model="photo"
onchange="angular.element(this).scope().file_changed(this)"
type="file" accept="image/*" />
It fails every time with error Cannot set property 'fileLoaded' of undefined.